GSW: 2007 MEETING MINUTES

 

Geological Society of Washington

Minutes of the 1406th Meeting,

Wednesday, January 24, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 PM sharp GSW President John Slack called to order the 60 attendees, who eventually quieted at approximately 8:02 PM.

The minutes of the 1405th meeting were read by a visibly and audibly choked-up outgoing speaker Bill McDonough as he realized it was his final appearance as meeting secretary. The surprisingly brief minutes were approved without further comment.

The following members introduced their guests: Liz Cottrell introduced Gene Hunt of the Smithsonian Institution and Linda Rowan introduced the AGI/AAPG Spring 2007 Intern Erin Gleeson and Mary Poultan of the University of Arizona.

Three new members were announced: Jordan Muller of the Department of State; Catherine O’Riordan of AGU, and Christina Silber, USGS retired. Ms. Silber, breaking with tradition, was actually in attendance. President Slack then held a short membership drive.

The passing of two former GSW members, Roger Wolff and James Luhr, both of whom passed away on 1/1/07, was then announced, followed by moments of silence.

Margaret Anne Baker made a plea for judges for several upcoming science fairs; more information is available on the GSW website.

President Slack informed the crowd that he was approached by a reporter from the Washington Post’s “Date Lab” (insert lame radiometric isotope joke here) who was looking for a single male volcanologist for a woman whose sad sad dream it was to date such a scientist. The question “Why single?” was asked by one “Wishes to remain anonymous/married”.

President Slack offered thanks to outgoing program chair Jay Kaufmann for his excellent work.

There was one informal communication by Harvey Belkin, in memoriam of Art Buchwald, about how Meyer Rubin and Edward Dwornik had “More than a passing fancy” regarding kidney stones, specifically regarding Buchwald’s exceptionally small stone. Much well-written, off-color humor by Buchwald, Rubin, Dwornik, and Frank Forrester, was relayed; chemical analysis of the stone was explained; and informative SEM photos of the frighteningly jagged little stone were shown. Buchwald offered his, and then President Ford’s, gratitude, equated the science with the moon landing, and recommended raises for all.

As usual, three talks were presented. The first talk, given by Michael Ryan of the USGS, was an exploration of the hypothesis that episodic eruptions may be solitary waves of magma, originating at depths up to 60 km, propagating through the mantle and crust as a fixed volume. The description and images of the solitons reminded me of peristalsis, or more specifically reverse peristalsis which is significantly less enjoyable. Data gathered from episodic eruptions in Hawaii were re-examined to see if they fit this hypothesis; Dr. Ryan concluded that they had soliton characteristics. The talk was followed by two questions from Dick Fiske of the Smithsonian Institution, and one each by Bill McDonough and Saswata Hier-Majumder of the University of Maryland, Linda Rowan of AGI, and Roz Helz of the USGS.

The second talk, given by Bill McDonough of the University of Maryland, was about Geo-neutrinos or “One man’s trash is another man’s treasure”. The detection of geo-neutrinos by the KamLAND experiment, which was intended for another purpose altogether, could be used to determine the Th/U ratio of the mantle to see if it was the same as in C1 chondrites. I found the discussion of the geo-neutrino detectors in deep underground lairs or sunken deep in the ocean very becoming of a James Bond villain, so that potential intrigue kept my attention. The recent estimates of the Th/U ratio and subsequent heat production of the mantle by Hawaiian researchers fit with Bill’s model, which made him happy. The talk was followed by two questions from Liz Cottrell of the Smithsonian Institution and E-an Zen of the University of Maryland, and one from Brooks Hanson of Science Magazine.

The final talk of the evening, given by Shuhai Xiao of Virginia Tech, featured remarkable photos and x-ray slices spliced together into three-dimensional representations of exquisite fossil embryos from the Ediacaran Doushanto Formation of China. The soccer ball and baseball-like structures of the outer wall of the embryos were preserved in several samples, which reminded me that spring training is around the corner and pitchers and catchers report in six days. The protective wall was partially removed in some fossils, which exposed the cells inside. The x-ray slices, when spliced together in a computer model, illustrated sub-cell structures which may have been organelles, and in other cells revealed internal textures similar to sponge embryos (or an odd diagenetic fabric). Also, pyrite-terminated tubes were observed in other cells. In answer to a recent Nature paper by Bailey et al., that interpret the embryos as giant sulfide oxidizing bacteria, Xiao points out that they ignore the protective wall which is unlike anything produced by bacteria. The talk was followed by two questions from Callan Bentley Northern Virginia Community College, and one each from Dan Milton of Reston (USGS Retired), Jay Kaufmann of the University of Maryland, and Jon Repetski of the USGS.

President announced the upcoming slate of speakers and the talk titles, and called the meeting to a close at 10:03 PM

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1407th Meeting,

Wednesday, February 7, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 GSW President John Slack called to order the 51 attendees, who came to order at approximately 8:01.

The minutes of the 1406th meeting were read and the audience politely laughed at the secretary’s poor attempts at humor. The minutes were accepted after the secretary was reminded of the difference between AM and PM (which will no longer be mentioned in the minutes) and to please pronounce names correctly.

The following members introduced their guests: Callan Bentley introduced two of his students from Northern Virginia Community college: Bill Barnett and Brian Finnigan-Stevenson; and Douglas Duncan of the USGS and Linda Billings and Catherine Conley of NASA introduced themselves.

One new member was announced: Dick Smith of the USGS, who was in attendance.

Margaret Anne Baker once again informed the society of several upcoming science fairs that still needed judges, along with a slew of new fairs that also needed judges, and asked members to please volunteer.

There was one informal communication by Sorena Sorensen of the Smithsonian Institution. Sorena gave a moving tribute to the late James Luhr of the Smithsonian Institution and GSW member, who passed away on 1/1/07.

As usual, three formal talks were presented. The first talk, given by Sarah Carmichael from the University of New Hampshire, tackled yet another instance of the “dolomite problem”. The dolomite problem involves the abundance of dolomite in the rock record, when it is never a primary mineral. As Dr. Carmichael stated, it is not really a problem, just a diagenetic process that needs to be unraveled. Her theory for the dolomite in the Latemar Triassic carbonate buildup of northern Italy is that the Iron, Manganese, and Zinc in the dolomite, the characteristic δ18O of the dolomite versus the unaltered calcite, and the geometry of the dolomite bodies within the limestone, indicates that the sources of the dolomitizing fluid was diffuse effluent from the Mid Ocean Ridge hydrothermal system. She then quantified the volume of fluid needed (huge, not surprising), and timeframe of the dolomitization (exceptionally fast, very surprising). Questions were asked by Dan Milton, USGS retired; Michael Ryan, USGS; Sorena Sorensen, Smithsonian Institution; Blair Jones, USGS; Brooks Hanson, Science; Pat Dobson, DOE; Sean Brennan USGS.

The second talk, given by John Rummel of NASA, was an overview of the NASA’s Astrobiology Program. The presentation was typical NASA, with cool graphics and movies just to let us lowly geologists know how much bigger their budgets are. Additionally, a budget slide was shown. The behind the scenes discussions about ensuring that our spacecraft and probes would not contaminate other planets and satellites were very intriguing. The research that John described, by scientists outside of NASA, was typically very interesting in a Discovery channel sort of way, replete with said graphics and movies. Questions were asked by Sorena Sorensen of the Smithsonian Institution and Brooks Hanson of Science Magazine.

The final talk, given by Andrey Bekker of the Geophysical Lab, was a re-examination of the widely held belief that sulfate concentrations in the oceans were low prior to 1.7-1.8 Ga as there are only rare instances of evaporates preserved in rocks older than that. However, Andrey’s field work on marine sediments deposited during the Lomagundi carbon isotope excursion between 2.22 and 2.1 Ga show abundant, pervasive, and globally dispersed instances of sulfate evaporite deposition. Several field photos of evaporite crystal casts were shown, and as geologist who has worked on evaporites extensively, I was convinced. One question was asked by Kateryna Klochko of the University of Maryland.

President Slack then announced the upcoming slate of speakers and their talk titles, and called the meeting to a close at 9:45.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1408th Meeting,

Wednesday, February 21, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 GSW President John Slack called to order the 73 attendees, by 8:01 most had taken their seats, but at 8:02 the tardy were admonished and slowly migrated to their seats.

The minutes of the 1407th meeting were read accepted without comment.

President Slack held a brief membership drive and pointed out the membership forms in the back of the room and noted their proximity to the beer. That choice for location was not an accident!

The following members introduced their guests: Brett Leslie of the Nuclear Regulatory Commission introduced “Buck” Ibrahim and Annie Kemmerer also from the Nuclear Regulatory Commission; Kevin Marvel of the American Astronomical Society introduced Tamara Koch and Uwe Gehlen; and Christopher Swezey of the USGS introduced Selene Deike.

The passing of former GSW member, Robert A. Weeks of the USGS, on 2/11/07, was then announced, followed by a moment of silence.

Margaret Anne Baker made yet another plea for judges for upcoming science fairs, and indicated that breakfast was provided for many of them. President Slack had a semantic disagreement with describing the food provided as “breakfast” but quickly pointed out that one does not necessarily volunteer for free food.

There was one informal communication from Dick Fiske of the Smithsonian Institution regarding the Nolan hammer. He began by insulting the hallowed Budweiser shillelagh, which he referred to as a “sissy-hammer” and replaced it briefly with a “Nolan hammer”. The Nolan hammer that he had was 3.7 lbs with the typical long handle, and was described as being able to “do the job”. The Nolan hammer was named after its creator, Tom Nolan 7th USGS Director. As a side note, I have a personal interest in that director, as his full name was Thomas Brennan Nolan, and mine is Sean Thomas Brennan. As some form of symmetry I feel as though one day I should be director, followed in the future by someone with the middle and last name of Sean Thomas, but I digress. Dick then presented the original Nolan Hammer, which he received from Tom Stern of the USGS, to President Slack to be displayed at the USGS National Center.

As usual, three formal talks were presented. The first talk, given by Kevin Furlong of Penn State, was an exploration of the creepy nature of the San Andreas Fault system. His fancy 3-D model led to quantification of necessary conditions for creep, which seemed obvious in retrospect. The fault section must be: 1. long and 2. “creepable” at depth, i.e. located over a shear zone that goes through the mantle. These conditions are met by the Hayward Fault which is quite creepable but not as much as the Southern Section of the San Andreas Fault which creeps at the full plate motion rate. The northward passage of the Hollister crustal triple junction, which is where the San Andreas Fault splits into the Hayward fault and San Andreas peninsular fault section, outlining the Bay area block, paved the way, much like a fullback in football, for the halfback, in this case the southern San Andreas fault, to creep along with little hindrance. Questions were asked by Jamie Allen of the NSF, Brooks Hanson of Science Magazine, and Michael Ryan of the USGS.

In the second talk, Francis Slakey of Georgetown took the breathless crowd up to the summit of Mt. Everest and back down. Without the familiar crutch of a powerpoint presentation, Slakey painted a detailed picture of the condition of the climb, and the deleterious effect those conditions have on the human body. His description of the base camp, the three week acclamation period prior to the final climb, the building of the camps at 20, 23, and 26 thousand feet, and the waiting for the optimal weather window, had everyone on the edge of their seats. Finally, his description of the death zone, and the sixteen hour hike from camp 3 to the summit, where all you can do is look for a second and then get down to camp 3 as quickly and safely as possible, was riveting. He also told a climber’s secret: the reason they climb is so that they can eat whatever they want. And apparently what one wants to eat when they finally return to base camp is a strawberry pop tart dipped in liver pate. Questions were asked by Annie Kammerer of the Nuclear Regulatory Commission, Dick Fiske of the Smithsonian Institution, an anonymous woman at the back of the room, Margo Kingston USGS retired, Kevin Marvel of the American Astronomical Society, Brooks Hanson of Science Magazine, Doug Rankin USGS retired, and E-an Zen of the University of Maryland.

The final talk, given by Christopher Swezey of the USGS, was an examination of the causes for the origin of the Sahara desert. Chris showed some initial slides which showed that, yes, the Sahara is a really REALLY dry place. Several desertification theories have been proposed, though none are convincing. The timing of the onset has been proposed as far back as 7 Ma, and as recently as 4 to 6 thousand years ago. One reason for the lack of clarity is a paucity of Cenozoic outcrop to provide evidence to support or refute any of the theories. Chris showed outcrop evidence which illustrated the evolution of the Sahara region from marine limestone deposition in the Paleocene, through arid and evaporitic in the Eocene, and fluvial from the Miocene through the Pliocene. There is pollen evidence from offshore Western Africa which indicates that the Sahara was arid from 3.5-3.2 Ma, humid until 2.6 Ma, and then arid ever since. Chris noted that that only event that coincides with the inception of aridiciation was the onset of major glaciation and expansion of polar ice in the Northern Hemisphere, though during questioning he did admit that there might be a lag time for the effect of earlier events to be felt. The talk was followed by two questions from Jamie Allen of NSF, and one each from Bill Burton of the USGS, Dan Milton USGS retired, Brooks Hanson of Science Magazine, E-an Zen of the University of Maryland, Mark Engle of the USGS, and Mack Ross USGS retired. 

President Slack then announced the upcoming slate of speakers, their talk titles, and that Craig Schiffries would be filling to run the 1409th meeting in his absence, and called the meeting to a close at 9:46.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1409th Meeting,

Wednesday, March 7, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:01 on a cold and snowy evening, GSW 1st Vice-President Craig Schiffries called to order the 57 attendees, by 8:02, after realizing that he does not yet command the respect that the President does, he decides to dive right in and talk over the din of the rabble.

The minutes of the 1408th meeting were read accepted without comment.

The following guests were introduced: Naomi Lubick of ES&T; Jonathan Price, State Geologist of Nevada, Beth Price, Nevada, Rob Swenson, State Geologist of Alaska, Roy Breckenridge, State Geologist of Idaho, Edmond Deal, State Geologist of Montana; someone named “Ryan” who I am assuming is Ryan Kerrigan (?), PhD student University of Maryland, and Annie Kammerer of the NRC.

Margaret Anne Baker made one final plea for judges for upcoming science fairs, and also informed the audience that an 8th grader wanted to shadow a geologist.

There were no informal communications.

As usual, three formal talks were presented. The first talk, given by the Director of the USGS Mark Myers, was an overview of the USGS plan for science in the upcoming decade. Being a USGS employee, I will not say anything snarky about this great talk. Did I mention he was the director? Dr. Myers laid out, with well illustrated slides, the USGS future research, which apparently will be on geologic hazards, environmental issues, climate variability, water issues, and energy and mineral issues. In essence, what the USGS has been doing for some time now. The talk was however, more “science-y” than your typical management-style presentation. Questions were asked by Walt Robinson of the NSF, a two part question by Brooks Hansen of Science Magazine, Naomi Lubick of ES&T, and Sean Brennan of the USGS.

In the second talk, given by Linda Hinnov from The Johns Hopkins University, was an in depth description of how astronomically calibrated timescales are better than any other dating method geologists have used to date. Or that is what she seemed to indicate. The talk described the ATS or astronomically-calibrated time scale, which is a re-branding of Milankovich theory. Milankovich theory posits that the changes in eccentricity of the Earth’s orbit, Precession of the angle of the Earth’s axis relative to the orbital plane, and Inclination of the Earth’s orbital plane relative to the sun. These processes occur on somewhat fixed cycles, and the thought is that these cycles create cyclicity in sedimentary layers, i.e. packages of similar layers of varying thickness in a given sedimentary unit. Each layer represents some fixed unit of time that varied from layer to layer, and those fixed units of time correspond directly to the orbital cycle. Questions were asked by Glen Chinery of the EPA, George Helz of the University of Maryland, and Mack Ross USGS retired.

The final talk, given by Nora Noffke from Old Dominion University, was an excellent overview of microbially induced sedimentary structures, a theory that was well documented by Dr, Noffke with photos and accompanying rock and sediment samples illustrating the sedimentary structures. The usage of careful observations of modern sedimentary structures clearly controlled by microbial activity, and then the application of those observations to interpret ancient sedimentary structures was remarkably clear, well documented and illustrated, and convincing. The utility of these observations was that the Dr. Noffke was able to identify cyanobacterial activity 2.9 Ga in South Africa. Questions were asked by Annie Kammere of the NRC, Rama Kotra of the USGS, and Brooks Hansen of Science Magazine.

Vice-President Schiffries then announced the upcoming slate of speakers, their talk titles, and called the meeting to a close at 10:04.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1410th Meeting,

Wednesday, April 11, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 GSW President John Slack called to order the 73 attendees, who quieted right away.

The minutes of the 1409th meeting were read and were accepted without any “official” comments.

The following members introduced their guests: Tom Simpkin introduced his neighbor Tom Head, who was also the first cousin of the second speaker; Rich Walker introduced Hagit Affek who is a postdoctoral researcher at Cal Tech; Cathy O’Riordan introduced her colleague from JOI Carl Ebeling; Pete Folger introduced Mark Wenzel who is the AGU congressional science fellow working for Senator Chris Dodd; and Linda Rowan introduced Craig Cooper who is the GSA congressional science fellow working for Senator Dianne Feinstein.

With all of the guests present, President Slack once again pounced with his impromptu membership drive and pointed out that the membership application forms were strategically placed next to the beer.

Four new members were announced: MaryAnn Malinconico from the USGS; Walter Robinson from NSF, Muffarah Jahangeer from George Mason University; and Libby Stern, all of whom were in attendance. Bully.

There were no further announcements or informal communications.

As usual, three formal talks were presented. The first talk, given by Laura Wagner of DTM, was an argument that a 500 Ma flat lying subducted slab of Laurentia, specifically part of what is now Texas, preserved beneath a portion of the Andes. There is evidence of a flat lying slab in the central Andes, however the seismic signature of that region is inconsistent with waves that pass through the serpentinized mantle formed above a “typical” flat lying slab. The seismic signature of the material in the region is consistent with cold, dry, depleted mantle, likely ancient lithosphere. The seismic signal is consistent with a enstatite-rich body, similar to the 1.6 Ga terrane in the Colorado Plateau and 2.5+ Ga terrane of southern Africa, which led Dr. Wagner to infer that the sub-Andean slab was also very old, and most likely a Texas-sized and sourced piece of Laurentia left behind 500 Ma. Questions were asked by: Liz Cottrell of the Smithsonian Institution, Brooks Hanson of Science Magazine, E-an Zen and Rich Walker of the University of Maryland, and Glenn Chinery of the EPA.

The second talk, given by James Head of Brown University, was a discussion of global climate change, ice ages, and tropical glaciers … on Mars. The glaciers on Mars are cold-based, as opposed to most earthly glaciers, which are wet-based. Therefore, the martian glaciers move differently, they flow by internal deformation rather than sliding along a surface. Mars has been subject Milankovich cycles in the same way that the Earth has, however the cycles on Earth are muted by the presence of our large moon. Dr. Head indicated that the two “space potato” moons of Mars cannot dampen the Milankovich cycles the same, so their effects can be much more dramatic, with the possibility for 75 to 80 degrees of obliquity. This high degree of variability on the obliquity has changed the nature and location of glaciers on Mars significantly. The imagery of glaciers along Arsia Mons were spectacular, and were useful for unraveling the glacial history of Mars. Using the observations of the structures left behind, they were able to construct a geologic model that was used to narrow the possible Milankovic spectra, which in turn might lead to exciting discoveries about the climactic history of Mars. Questions were asked by George Helz, E-an Zen and Rich Walker of the University of Maryland, Chris Swezey of the USGS, Walt Robinson of NSF, and Mark Wenzel, the current AGU congressional science fellow.

The final talk, given by Charlotte Sullivan of Pacific Northwest National Laboratory, was on cutting-edge 3-D seismic techniques and their utility as a tool for CO2 sequestration monitoring. Geologic CO2 sequestration is a method for taking CO2 from the emission streams of major point sources, such as power plants, and pumping it into deep subsurface reservoirs. Therefore, there is a critical need to ensure that the CO2 will stay underground, and more specifically where someone can keep and eye on it. Or more specifically, since seismic techniques will be used … keep an ear on it. Dr. Sullivan described a series of cutting edge seismic techniques that will be employed, and as usual, the seismic images constructed were really cool looking. Unfortunately, she is looking for really boring geology for 3-D seismic for CO2 sequestration, to make it easier to see the CO2, and to avoid any unpleasant “surprises”. Questions were asked by: Muffarah Jahangeer of George Mason University, Hal Gluskoter, USGS retired, Glenn Chinery of the EPA, Mack Ross, USGS retired, and George Helz, University of Maryland.

President Slack then announced the upcoming slate of speakers and their talk titles, and called the meeting to a close at 9:34.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1411th Meeting,

Wednesday, April 25, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 GSW President John Slack called to order the 74 attendees.

The minutes of the 1410th meeting were read and were accepted without any “official” comments.

The following members introduced their guests: Andy Campbell of the University of Maryland introduced the GSW science fair winner Graham Taylor, and his proud parents Dennis and Helene Taylor. Charna Meth of JOI introduced Alicia Wallace of Ketchum, Christa Peccianti of Basis, and Trevin Sanlin of AAAS.

Four new members were announced: Nora Noffke of ODU, Ricardo Olea of the USGS, Charlotte Sullivan of Pacific Northwest National Laboratory, and Doug Duncan of the USGS.

There were three informal communications. The first informal communication was by Graham Taylor, presenting his award winning project on fugacity reactions at high temperatures and pressures. The project was the result of his high school research practicum, which he completed at the University of Maryland with Andy Campbell. Using the NNO (Ni-NiO) and IW (Iron-Wustite Fe-FeO) buffers, he was able to show that at as the pressure of the system increased, there was a correlative increase in the oxygen fugacities necessary to covert metal to oxide.

Two announcements provided a brief respite in the informal communication deluge.

Linda Rowan informed the crowd of an upcoming (and now long completed) Art Exhibit at AAAS by Michael Collier

Rama Kotra invited all to an upcoming (And once again, long wrapped up) party for Pat Leahy’s retirement from the USGS, and to celebrate his next career with AGI.

Then it was back to the never ending informal communications. Jane Hammarstrom of the USGS, accompanied by theme music from Dragnet, told a story of good badges gone bad. The lone incorrigible IRS badge was left in a bag and came out covered in a suspicious white powder. USGS was asked to solve the crime … uh … mystery. Some powder was scrapped off the badge and run through the XRD, the powder was  Gold-Mercury mixture. Microprobe analysis indicated the presence of Au and Hg. Where the powder was absent, only Au was present so the bag must have had the Hg powder in it. Upon further interrogation, a sheepish IRS agent admitted that there may have been a high blood pressure cuff in the bag, which was the likely source of the Hg. Case closed. Dum-de-DUM-dum …. DUMMMMM.

The final informal communication was presented by Jim Gill of UC Santa Cruz, UCDC program, on the Changbaishan/Paektusan Volcano which straddles the China-north Korea border. Approximately 1000 years ago the volcano known as Changbaishan in China and P'aektu-san in Korea was the site of one of the largest eruptions of the Holocene, with material reaching Japan. It is an iconic feature for Koreans, who believe that their ancestors descended from the volcano to populate the peninsula. Jim showed pictures of this amazing volcano, which is rarely seen by Americans.

Finally the formal program began. As usual, three formal talks were presented. The first talk, given by Catherine Cooper of DTM, was a thought exercise on what could be learned from the interaction of cold cratons and the 410-km discontinuity. The 410-km discontinuity is defined by the transition of olivine to spinel, however if there is a temperature decrease without a resultant pressure decrease, the discontinuity is deflected upwards to a more shallow depth. If the 410-km discontinuity showed positive topography beneath thick, cold cratons, then cratons would affect the deep mantle. However recent measurements beneath the Eastern US and Kaapaval indicate that there is no correlative topography of the 410-km discontinuity. Dr. Cooper then showed via relatively elegant models that the lack of topography of discontinuity provides a significant boundary condition, and that the thickness of cratons, cannot exceed 370 km because any thicker and their thermal “aura” would interact with the discontinuity. Questions were asked by Linda Rowan of AGI, Dan Milton, USGS-retired, Brooks Hanson of Science Magazine, and Allan Linde of DTM.

The second talk, given by Dave Houseknecht of the USGS, was on dramatic coastal erosion along the Arctic coast of Alaska over the past 50 years. Using legacy data and dramatic field photos Dave was able to show remarkable erosion via undercutting of permafrost by wave action. Average rate of land loss from 1955 to 1985 was 0.5 km2/yr and from 1985 to 2005 was 1.1 km2/yr. The most dramatic photos of shoreline retreat show the the JW Alton well, which was initially sited 1500 m from shore before 1985, going from onshore to offshore during 2004 through 2005. Climate change is a major reason for the erosion, higher temperatures have caused both the permafrost to melt and the volume of sea ice to an decrease, which results in an increase the wave energy reaching the shoreline, and rising sea levels causes more erosion as well. Questions were asked by E-an Zen of the University of Maryland, Dan Milton, USGS-retired, Callan Bentley of NOVA Community College, Glenn Chinery of the EPA, Brooks Hanson of Science Magazine, and two questions by Naomi Lubick of ES&T.

The final talk, given by Andrew Cohen of the University of Arizona, described the Lake Malawi drilling project. Andrew described the monumental task of building a floating drilling rig from scratch, but the success has led to long cores with remarkable recovery. Previous seismic work in Lake Malawi indicated that there were periods of remarkably low lake levels. Evidence of paleosols in the core corroborated the seismic data, and indicated that the lake levels had been 590 m lower than present during the early Late Pleistocene. The mega-droughts may also have had an impact on hominid migration patterns during this time, little hominid remains are found in the mega-drought regions of central Africa, and most remains are found to the north and south at higher elevations. The end of the mega-droughts coincides with onset of aridity elsewhere in Africa and may have helped spur hominid migration out of Africa. Questions were asked by Liz Cottrell of the Smithsonian Institution, Blair Jones, USGS very recently retired, and E-an Zen of the University of Maryland.

President Slack then announced the date of the next meeting without the customary introduction of the upcoming slate of speakers due to the very long summer hiatus, and called the meeting to a close at 9:49.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1412th Meeting,

Wednesday, September 26, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:00 acting GSW President Craig Schiffries called to order the 45 attendees, and dove right into the proceedings before several laggards quieted and took their seats.

The minutes of the 1411th meeting were read and were accepted after one correction was noted.

The following members introduced their guests: Callan Bentley of Northern Virginia Community College introduced his student Victoria Martin also of Northern Virginia Community College; and Rich Walker of the University of Maryland introduced Gwen Rhodes, Lisa Schleicher, and Xiaoming Lu, all graduate students from the University of Maryland.

No new members were announced but acting president Schiffries quickly noted that new membership forms were in the back of the room. I am happy, yet a touch embarrassed, to point out that at the end of the meeting all the forms had been snatched up by potential new members, so I hope to soon announce a flood of new members. I just hope that we didn’t lose any by underestimating the demand.

There were two announcements, and in stark contrast to the previous meeting, no informal communications.

 Joe Smoot, obviously pining for better, happier times, informed the crowd that anyone who wanted to attend the Fall GSW field trip would not only be traveling to Shenandoah National Park, but also back to 1997. Unfortunately, to my personal chagrin, the trip is actually on October 20th, 2007 and it was just a typo. Oh well, trips to happier, simpler times will have to remain in my daydreams. The modern day field trip will be to outcrops of the early Paleozoic Chilhowee Group, which record the opening of the Iapetus Ocean. More information can be gathered from the Geological Society of Washington’s website.

Callan Bentley made an announcement for Rick Diecchio of George Mason, who is leading a field trip to Ecuador for one week in the Andes and one week in the Galapagos Islands. The trip will be from January 3-18th, 2008. Unfortunately, all the spots are now filled, but there is a wait list. Contact Rick Diecchio for more information.

The announcements were followed by the formal program. As usual, three formal talks were presented. All of the talks were around a common theme of convection and unusual yet predictable changes in convection due to thermodynamic and physical perturbations in the system.

The first talk, given by Walt Robinson of NSF, was about atmospheric jets. The talk began with a primer on how they form and was followed by a discussion of the reciprocal effects between changes in the climate and the jets. Recent climate models for the latter part of this century predict that global warming will cause Hadley Cells become weaker and broader, driving the jets and subtropical drying poleward. The Hadley cells will become, in Dr. Robinson’s words, “juicier” but there will be less precipitation. So the evaporation will outpace precipitation, and there will be larger surficial areas subjected to drought conditions over the next 100 years. Dr. Robinson informed the crowd that that is “bad news” then quickly qualified it with the common refrain of anyone who deals with models will concede … “if model projections … are right”. Questions were asked by Joe Smoot of the USGS, and Brooks Hanson of Science Magazine.

The second talk, given by Maureen Long of DTM, was a remarkably accessible talk on geophysics about how subducting slabs can affect mantle flow fields, and more specifically about how the classical 2-D model of mantle flow near subducting slabs may not be correct. Mantle flow can be measured using shear wave splitting observations as shear waves travel through the anisotropic upper mantle. Observations show that the sub-slab mantle flow is controlled by the trench migration velocity and not the pull of the subducting plate. Furthermore, in the wedge there are competing forces from the classical 2-D corner flow controlled by convergence velocity and by 3-D edge flow around the slab margins from the sub-slab side to the wedge controlled by the trench migration velocity. If this model is correct, then the slab and the sub-slab mantle are decoupled. The flow of the mantle below the slab and around the edge of the slab reminded me of watching my Mom silk-screening shirts. Questions were asked by Michael Ryan of the USGS, Dick Fiske of the Smithsonian Institution, Jamie Allen of NSF, Brooks Hanson of Science Magazine, Joe Smoot of the USGS, Craif Schiffries, and Saswata Heir-Majumder of the University of Maryland.

The final talk, given by Michael Fromm of the U.S. Naval Research Lab was on the discovery of Pyrocumulonimbus and their affect on the Stratosphere. The prevailing dogma was that the only volcanic eruptions could break through the tropopause and introduce particulate matter into the Stratosphere. However, based on observations after the fire season of 1998, two separate labs identified particulate matter in the Stratosphere, seemingly unrelated to volcanism. The labs did back tracking calculations on the source of the particulates, which seemed to match up with locations of large wildfires. The smoking gun came from a Canadian fire on August 3rd, 1998, which led to a swirling mass of smoke that could be seen in “SeaWIFS” real-color satellite imagery. This swirling mass, coupled with the intense heat of the out of control fires in the boreal forest, is what provided the energy to drive the particulate matter into the Stratosphere. Upon re-examination of historical data, the labs were able to document previous such fire-aided breaching of the Tropopause. Questions were asked by Dan Milton, USGS retired, Patrick Durbin of Lawrence Berkley National Laboratory, Brooks Hanson of Science Magazine, George Helz of the University of Maryland, Walt Robinson of NSF, and two questions by Linda Rowan of AGI.

Acting president Schiffries then announced the date of the next meeting, the upcoming slate of speakers, and called the dogma-crushing, thermodynamic-themed meeting to a close at 9:39.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1413th Meeting,

Wednesday, October 10, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 7:59 GSW President John Slack called to order 79 attendees, and waited patiently, too patiently, for the rabble to quiet. At 8:01, when a quasi-quiet state was reached, President Slack began the meeting.

The minutes of the 1412th meeting were read and accepted.

The following members introduced their guests: Fred Simon, USGS retired, introduced Peter Johnson and George Varances, of JV Associates; An Leonard Johnson from NSF introduced Michael Ellis also of the NSF; Joe Smoot, USGS, introduced Mark McDonough of Vision, Liz Cottrell of the Smithsonian Institution introduced Eloise Gaillou, who is currently a post-doctoral researcher also at the Smithsonian Institution; Chris Swezey of the USGS introduced Maria Vargas of the EPA; and Manik Talwani of Rice University and the Integrated Ocean Drilling Program introduced himself and his wife.

Two new members were announced: Graham Taylor, a recent graduate of Eleanor Roosevelt HS and GSW science fair winner, and Rick Wunderman of the Smithsonian Institution, who may have already been a member.

There were no informal communications, but there were five announcements.

 Joe Smoot gave one last pitch for his GSW fall field trip.

President Slack informed the crowd of the upcoming USGS open house, which will take place Saturday November 3rd, the weekend after the GSA annual meeting.

Mark McBride of the NRC told the group that the NRC was looking to hire 1000 new employees, but quickly cautioned that most would not in fact be geologists. They have 30 new nuclear power plants that are up for licensing, which is why they need lots of help.

Rama Kotra of the USGS, after a playful jab at the NRC, mentioned that the USGS was looking on a more modest scale to fill Mendenhall postdoctoral research positions at the USGS.

And finally, President Slack told the members present that the current dues only cover approximately 63% of the meeting cost. Interestingly, that missing 37% is the same as the cost of the traditional and lovely beverages found in the back of the room. So please consider adding an extra donation to the general fund with your dues payment. Remember, all donations to GSW funds are tax deductible. Also, there will be a meeting next year, called the Bradley Lecture, which will be paid for from the Bradley fund.

The announcements were followed by the formal program. As usual, three formal talks were presented. If I understood correctly, the night’s theme was the Badger, or more specifically, Wisconsin. All speakers had some connection to the land of beer and cheese.

The first talk, given by Basil Tikoff of the University of Wisconsin was another in a series of recent interesting San Andreas Fault System presentations at GSW. Basil covered two seemingly disparate topics, the effect of the Fault system on the crust, and the effect of the fault system on the mantle. The fault is slipping at a rate of 28 mm/year, however, the plate motion is 39 mm/year. The difference in the two rates is taken up in deformation associated with transpression, which is a combination of pure and simple shear. The resultant deformation creates folds, with axes that rotating in the direction of fault motion, while undergoing hinge-parallel extension. As for the lithospheric mantle, we were treated to a second straight week of shear wave splitting evidence, with the same explanatory cartoon from Ed Genaro’s website. The shear wave splitting evidence indicates that the mantle has a fabric consistent with a continuation of the fault into the mantle. Questions were asked by Bill Burton and Joe Smoot of the USGS, Carter Hearn, USGS retired, Steve Shirey of DTM, Rich Walker of the University of Maryland, and two questions by Peter Johnson of JV Associates.

The second talk, given by Giovanni Sella of the National Geodetic Survey and went to school in Wisconsin, involved measurements of Glacial Isostatic Adjustment, or the crustal response to the removal of massive ice sheets at the end of the last glaciation. The mass of the ice sheets depressed the crust, which caused the mantle to flow away from the pressure. With the melting of the ice sheets, the mantle is flowing back, causing the crust to rebound. The rebound velocity can be measured using high precision Global Positioning System monitors. In North America, the rebound is fastest in the Hudson Bay region at 10 mm/year, with 1-2mm/year north of the Great Lakes. South of an east-west lineament just north of the Great Lakes, the velocity is negative, indicating a slight deflation of the mid-continental crust. However, current modeling efforts can’t fully explain the crustal behavior. Questions were asked by Bill Burton of the USGS, E-an Zen of the University of Maryland, Mike Ellis of NSF, Basil Tikoff of the University of Wisconsin, and Linda Rowan of AGI.

The final talk, given by Jeffery Post of the Smithsonian Institution and a Wisconsin native, was on studies of the Hope Diamond and other blue diamonds. The talk was on two research topics, one involving computer modeling of the diamond to determine if it could have been cut from the French Blue of the French Crown Jewels, which itself came from the Tavernier Blue of India. Using historical records and unusually precise drawings, Dr. Post and his collaborators were able to reconstruct three-dimensional models of the three diamonds, only two of which involve remarkable detective work. The models show that not only do the diamonds all fit neatly into one another like nestling dolls, but that according to gemologists, the cutting techniques employed at the time of the creation of the French Blue and the Hope diamonds rule out the existence of any daughter gems. So the Hope is all that is left of the Tavernier Blue. Secondly, the Hope Diamond has remarkable red phosphorescence when exposed to intense UV light. Spectrographic measurements of the phosphorescence indicate that there is actually a short-lived blue green color at roughly 500 microns, and a longer-lived red color at roughly 660 microns. Studying other blue diamonds with the same spectrometer, Dr. Post and his colleagues were able to determine that those phosphorescence colors were present in all the blue diamonds, but that the persistence and intensity varied. And no diamond had the red persistence that the Hope diamond did. Questions were asked by Pete Toulmin and Carter Hearn, USGS Retired, Jeff Grossman, USGS, and two by Dan Milton, also USGS retired.

President John Slack held one final membership drive, made one final pitch for the fieldtrip, announced the date of the next meeting, with the upcoming slate of speakers, and called the cheesehead meeting to a close at 9:52.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1414th Meeting,

Wednesday, October 24, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 7:59 on a dreary, rainy night, made more depressing by the Red Sox beginning their World Series triumph, GSW President, and giddy Red Sox fan, John Slack called to order 36 attendees. Though the crowd was quiet immediately, President Slack still waited until 8:00 sharp to begin.

The minutes of the 1413th meeting were read and accepted though one correction was noted after the meeting.

The following members introduced their guests: Elise Struts and Anne Kammerer of the NRC introduced themselves, but indicated that they were invited by Mark McBride also of the NRC; George Varances of JV Associates and Victoria Martin of NOVA CC introduced themselves as well.

Three new members were announced: Peter Johnson of JV Associates; Xiaoming Liu a graduate student from the University of Maryland; and Kristin Bennett, the Program Manager for DOE EPSCoR.

There were five announcements and one informal communication.

 President Slack:

1.            Thanked Joe Smoot for running the GSW fall field trip.

2.            Gave a last plug for the overwhelming successful USGS open house.

3.            Reminded people that the renewal notices had gone out and to please send the dues moneys back as soon as possible, and to please consider an extra donation to one of the GSW funds.

4.            Introduced a proposed amendment to the GSW bylaws

5.            Rama Kotra again mentioned the looming deadline for the USGS Mendenhall postdoctoral program, and told the crowd if they, or anyone they knew, were interested to please apply

Jeff Grossman of the USGS gave an informal communication regarding an unusual meteorite that fell to Earth at approximately noon on September 15th, 2007, near Carancas, Peru, a small town on the border to Peru and Bolivia sorth of Lake Titicaca. The meteorite came in low over Bolivia and Lake Titicaca before impacting in Peru, leaving behind a 13 to 14 m wide and approximately 6 m deep crater that quickly filled with water due to the high water table. There are several things that were interesting, both scientifically and otherwise about the meteorite. Scientifically, it is very intriguing because it is the first recorded H5, i.e. “stony”, meteorite that has created a crater. The stony meteorites are highly friable and tend to break up during their travel through the Earth’s atmosphere. On the “otherwise” front, there were claims of people being sickened by a foul odor coming from the crater but are unsubstantiated to date. Also, an American collector Michael Farmer went into the village and bought up all the meteorite fragments that he could before having to quickly leave the country. Some estimates indicate that the meteorite was 10 tonnes, which would indicate that there is a significant chunk of rock still left in the crater; if that chunk exists, it has not been found yet. However, sitting in a big crater of trash and urine-rich water does not indicate that the meteor will remain intact for very long. Questions were asked by Craig Schiffries of the new GSA Washington DC office; and Jamie Allen of NSF.

The announcements were followed by the formal program. Unfortunately, due to an emergency with the second speaker, two formal talks and an AGI film clip were presented. In the first talk, Katherine Maher of the USGS Mendenhall postdoctoral program, presented a novel methodology for precisely dating high resolution paleoclimate data. Dr. Maher and her colleagues at the USGS were able to use the SHRIMG-RG to date soil opal with Th-U isotopes, a method that has high precision for samples up to 500 ka. The small ion beam used for the SHRIMP analyses makes it possible to do multiple measurements on individual crusts to see changes over time in a sample that would otherwise be homogenized in other analytical methods. When combined with δ18O analyses, the data can be compared with other oxygen isotope paleoclimate records to add another terrestrial record to the mix. Questions were asked by George Helz of the University of Maryland; Liz Cottrell of the Smithsonian Institution; Brooks Hanson of Science Magazine; and Sean Brennan of the USGS.

The AGI film clip, brought to the meeting by Linda Rowan also of AGI, was 6 and a half minute draft of a video entitled “Why Earth Science?”, which has been created to help with the lack of interest in Earth Sciences at all education levels. The high tech speaker system comprised of a lavaliere microphone resting on a laptop speaker was effective enough for the crowd. However, several failed attempts at trying to turn on the laptop volume caused a brief delay. The general helpfulness of the suggestions from the crowd was dubious at best, but the show did, in fact, go on. The film was a series of rapid cuts culled from hundreds of hours of an AGI and Discovery Channel co-sponsored series on Earth Science, and was designed to be an introduction to a talk or presentation given by an Earth Science professional for an audience of educators or their students. Though it has the potential of being an exciting introduction, it ain’t exactly the theme from Rocky. Questions were asked by Liz Cottrell of the Smithsonian Institution; George Verances of JV Associates; Anne Kammerer of the NRC, Mack Ross a mineral consultant; Callan Bentley of NOVA CC; Nick Woodward of DOE; Jamie Allen of NSF; Mark Zerniak of the State of Maryland, and two questions each from George Helz of the University of Maryland; and Alan Robick of Rutgers University.

The second and final talk, given by Alan Robick of Rutgers University, involved the climatic consequences of nuclear conflicts. This work was an update of the nuclear winter concept which was first described and modeled twenty years ago. There were several levels of hypothetical scenarios, from a relatively small conflict such as a border war between India and Pakistan up to a full nuclear holocaust of a total deployment of all extant nuclear weapons. The models were based on how much smoke would be produced by the various scenarios, the border war was assumed to create 5 Tg of smoke, there was another scenario run with 50 Tg, and a total nuclear war of 150 Tg. The 5 Tg smoke scenario would strongly affect climate, dropping global temperatures between 1 and 1.5 degrees over the first few years and not leveling off for approximately a decade. The 50 Tg scenario would drop temperatures 4 to 5 degrees, and the 150 Tg scenario would drop temperature 7 to 8 degrees, either of which would be catastrophic. The point that Dr. Robick made is that, beyond the unmitigated horror of the actual nuclear strike and minimum of tens of millions dead in the smallest scenario, any such scenario would affect the Earth more strongly, and be globally more catastrophic, than even the modelers would have predicted. After that cheery note, questions were asked by Liz Cottrell of the Smithsonian Institution; Mark Zerniak of the State of Maryland; Pat Dobson of Lawrence Berkeley National Lab; Dick Smith and John Eichelberger of the USGS; Brooks Hanson of Science Magazine; and two questions by Mack Ross, mineral consultant.

President John Slack announced the date of the next meeting, the upcoming slate of speakers, and called the meeting to a close at 10:00.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1415th Meeting,

Wednesday, November 14, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 8:01 GSW President John Slack called to order 65 attendees, and though the crowd was quiet immediately, President Slack still waited until 8:02 begin.

The minutes of the 1414th meeting were read and were accepted after George Helz objected to the description of the AGI film, presented by Linda Rowan, as being intended for an educational audience. His contention was that the film was for an audience of educators, with the implication that said educators presumably are no longer, or no longer wish to be, educable.

The following members introduced their guests: Wright Horton of the USGS introduced Lauren Jolly and Gabi Townsend of Witwatersrand University in South Africa; Callan Bentley of NOVA CC introduced Anastasia Bogosian a student at NOVA CC; and Tim Baker of Applied Environmental and Adam Bernstein of the Army Corp of Engineers introduced themselves.

Two new members were announced: John Eichelberger of the USGS and Luidmila Eichelberger a volcanologist from Petropovlovsk, Russia.

There were three announcements, one discussion and vote on a bylaw change, and two informal communications.

 

President Slack:

1.      Mentioned that the renewal forms are now downloadable from the GSW website.

2.      Reminded people that the renewal notices had gone out and to please send the dues moneys back as soon as possible, and to please consider an extra donation to one of the GSW funds.

3.      Introduced the 2008 slate of GSW officers, with a vote to take place at the 1416th meeting in December.

The bylaw amendment, which was introduced at the 1414th meeting, was read again by President Slack. The discussion was led by E-an Zen, who suggested that the phrase “at least” be struck from the bylaw. Jeff Grossman indicated that there was no limit on the number of members of the Finance Committee to which E-an replied, shouldn’t there be a limit? George Helz, obviously making a last ditch effort to grab that coveted Sleeping Bear award, intimated that, since he was so interested, E-an should forcibly be placed on the Finance committee. The bylaw change was carried with a unanimous vote.

Two informal communications were presented. The first, given by Derek Richardson of the University of Maryland, who also gave a formal presentation later in the evening, was a presentation of a high definition video captured by the Japanese Kaguya Spacecraft.

The second informal communication, presented by David Applegate of the USGS, was a description of that day’s 7.7 magnitude earthquake in Chile and an introduction to a new USGS product: “PAGER” or Prompt Assessment of Global Earthquakes for Response. PAGER gives a large amount of data about individual earthquakes very rapidly (within tens of minutes) including the location of the earthquake, the magnitude, the cities and people affected. Furthermore, it serves as a place where people can let the USGS know if and how strongly they felt the earthquake.

The announcements, bylaw discussions and vote, and informal communications were followed by the formal program. The first talk, given by Bridget Scanlon of the Texas Bureau of Economic Geology and the University of Austin, was on the effects of changing land usage on subsurface water resources. Dr. Scanlon’s showed that within the Ogallala Aquifer in the High Plains of the US, irrigated crops comprised 12% of the total surface lands, but accounted for 90 to 95% of the total water usage from the aquifer. Irrigation is causing an increase in the depth to water in the aquifer; however, in rain-fed crops and in urban areas, the depth to water was decreasing. Conversely, changes from natural grasslands to rain-fed croplands can cause drastic, and potentially unwelcome, increases in water levels. Dr. Scanlon suggests changing water use patterns, switching between irrigation and rain-fed croplands,; and to use agriculture to manage water resources: “more crop per drop”. Also, she suggests that if you truly want to do something for the environment to “Become a veggie”. Questions were asked by Nick Woodward of DOE, Al Taylor of Nomad Geosciences, Brooks Hanson of Science Magazine, Bill Burton and John Eichelberger of the USGS, Virgil Frizzell of Long and Foster’s, with two questions by E-an Zen of the University of Maryland and the impressive hat trick of questions by Mark Engle of the USGS.

The second talk, given by Bill Cannon of the USGS, explored the evidence for the 1850 Ma Sudbury impact that created a crater 200 km wide, making it the second largest discovered impact crater on Earth. The evidence for the impact was discovered by two retired high school teachers, Greg Brumpton and Bill Addison, who pushed their theory until the geologist who worked in the iron ranges of Michigan finally believed them. The impact theory finally explained bizarre textures that Bill and others had documented for decades, evidence of ejecta layers, tsunami features, shock metamorphic features in the quartz, and accretionary lapilli up to 700 km away from impact site. The iron deposits that were common prior to 1850 Ma never reappeared, so it seems that the impact had global and historical ramifications. Questions were asked by Jamie Allen of NSF, Dick Fiske of the Smithsonian Institution, Steve Shirey of DTM, Bill Burton of the USGS, Callan Bentley of NOVA CC, Brooks Hanson of Science Magazine, and E-an Zen of the University of Maryland.

The final talk, presented by Derek Richardson of the University of Maryland, involved a introduction to the discovery of asteroid binaries, how they might form, and some possibilities for how they evolve. Using computer animation that is common amongst space folks, causing irrational envy in many of the geologists in the audience, Derek showed how these binaries form from tidal forces caused by the parent asteroid getting too close to a planet (or moon?). The asteroids in the binary systems are essentially a spinning ball of sand held together by gravity and centripetal force (I think). Then any perturbations to the spinning of the asteroid, such as by tidal forces, can cause the spinning sand ball to be torn apart, then fly back together potentially creating a smaller orbiting asteroid “moon”. These systems are ephemeral, lasting only a few million years at the longest. However, planets (and other moons) are not the only celestial bodies to have satellites. The Derek freaked everyone out by telling us that there is an asteroid that will come really, really close to Earth in 2029, but it probably won’t hit us. But it might be a good time to observe the formation of a binary asteroid system. Questions were asked by Rich Walker of the University of Maryland and Bill Burton of the USGS.

President John Slack announced the date of the next meeting, which will be the presidential address, followed by the annual meeting, and called the meeting to a close at 10:01.

Respectfully submitted,

Sean T. Brennan

 

Geological Society of Washington

Minutes of the 1416th Meeting,

Wednesday, December 5, 2007

John Wesley Powell Auditorium,

Cosmos Club, Washington, D.C.

At 7:59 GSW President John Slack called to order 49 attendees, and 8:00 at again asked for order.

The minutes of the 1415th meeting were read and accepted without comment.

The following members introduced their guests: Doug Rankin, USGS retired, introduced Peter and Thelma Thompson of the University of New Hampshire; and Robin Brett, USGS retired, introduced Ian MacGregor of NSF.

Three new members were announced: Victoria Martin, a student at NOVA CC; Ann Kammerer of the NRC, and Louise Hose of the NPS. Victoria and Louise, not familiar with the GSW tradition of being absent for one’s introduction, were in fact present.

There were no announcements.

 Following tradition, which is especially important in these Presidential address meetings, President-elect Craig Schiffries introduced President Slack, and his talk on the redox state of Proterozoic seawater. Previous modeling efforts of Proterozoic seawater generally agree that prior to 1.8 Ga, the deep oceans were anoxic. However after this date there is no consensus, one camp favoring oxic conditions and the other sulfidic conditions like those that exist in the lower part of the modern Black Sea. In order to test which model is correct, Slack used mineral assemblages and rare earth element compositions of exhalative chemical sedimentary rocks (exhalites) from two Cu-rich VMS deposits: the 1.74 Ga Jerome deposit in central Arizona and the 1.72 Ga Jones Hill deposit in northern New Mexico. Exhalites near both deposits have REE signatures (small positive or no Ce anomalies) that are consistent with precipitation from hydrothermal-seawater fluid mixtures under suboxic conditions. Exhalites including jasper and hematite iron formation near the Jerome deposits lack manganese concentrations, whereas magnetite iron formation south of the Jones Hill deposit contains abundant Mn-rich garnets, which likely formed from a protolith of Mn-rich carbonates+clays.. MnCO3 and ferric iron (present in magnetite) coexist only under suboxic conditions, which implies that neither camp is correct about the redox state of the Proterozoic deep oceans. Suboxic conditions would have had the same effects on dissolved iron in the deep oceans as sulfidic conditions. Both scenarios proposed that iron of seafloor-hydrothermal origin precipitated in the deep ocean (as FeOOH versus Fe-sulfide), thus removing dissolved iron from the phosphate-rich waters upwelling onto oxic shelves. No dissolved iron means that little or no iron precipitated at shallow depths, and also means that PO34- was not adsorbed by precipiting Fe-oxyhydroxides. Therefore, PO34-, which is a critical nutrient for marine organisms, would have been abundant at the shallow depths where eukaryotic life could flourish. Finally, in an attempt to explain how the deep ocean redox conditions changed relatively rapidly, from anoxic to suboxic, Slack called on the impact of the giant Sudbury meteorite at 1.85 Ga. This event may have been so catastrophic as to cause the ocean to overturn, mixing oxic shallow surface waters with anoxic deep waters, thus creating suboxic conditions in the deep oceans. This impact may have simultaneously ended the formation of BIFs globally, and ushered in the genesis of eukaryotic life on Earth. President Slack then ended his presentation by informing the crowd, “Now I need a beer.” Again, as per tradition, no questions were asked after the Presidental address.

President John Slack announced a 10 minute break before the next meeting, which was the 115th annual meeting, and called his final regular meeting to a close at 8:58 PM.

Respectfully submitted,

Sean T. Brennan