GSW: 1986 MEETING MINUTES

 

Geological Society of Washington -- 1146th Meeting

January 8, 1986

     President Brett set a punctuality precedent by calling the 1146th meeting to order at 8:05 pm. Despite freezing weather a passel of visitors was introduced, including Janet Herman, an Environmental Scientist, Carolyn Olsen, Isabella Corelli, Bruce Johnson, Erhart Lab, Rich Hildebrand and colleague Ed all of the USGS, Luret Savoy, University of Colorado, Elizabeth Ryan of Langston Hughes High School, introduced by her father, Mike and Laura Widiker of West Virginia. My apologies to those I may have missed due to unhoned speed writing skills. New members, Charlotte Abrams of the NRC and Russ Campbell, USGS were welcomed with applause.

     President Brett announced that since "making money makes the world go round", the bargain priced GSW tee-shirts were still available. He then read a thank-you note from the 1985 recipient of the Best Paper Award, Harry McSween. Third Brett hinted darkly at some discordant exchange between E-an Zen and the Sleeping Bear Award Chairperson, and promised to further enlighten us only when Zen was present to defend himself.

     William Seyfried gave the first talk entitled "Ridge-crest hydrothermal processes: experimental models and field observations."  With a wry glance at our president, Seyfried noted the difficulties of studying these black smokers in situ even with the Alvin. In his cozy lab, Seyfried reproduces these submarine systems in the Dickson cell which is a fancy toothpaste tube. He has found that the concentrations of SiO2, chlorine and clinozoisite are useful for estimating temperature, pressure and pH. Seyfried summarized his results with a cartoon showing that these hydrothermal fluids form in a hotter and deeper system than had previously been reported. Questions by Helz, Doe, Jones, Hemley, Howzer and Hazelton. Sellers had questions during the talk.

     The second speaker, Linda Gunderson, presented a "geochemical and tectonic model for the formation of the Fe-U-REE deposits in the Proterozoic rocks of the Reading Prong". We viewed a slide series of lithologies and chemical compositions, discovering that Gunderson's favorite rocks and adjective are the same and quite nice. The magnetite deposits of her study area started out as banded iron formations back in a Precambrian basin. Relaxed listeners were startled by a slide which showed the uranium content of Reading Prong rocks to be 40,000 ppm, but our speaker quickly calmed us with the word "typo." As indoor radon is such a hot item, this was a disquieting error indeed! Questions by Robertson, Milton, Hatch, Helz and anonymous.

     It was a banner evening for geochemists, as the final talk by Paul Hearn was entitled, "Geochemistry of rock-water interaction in the Columbia river basalts". Hearn charged that these waters flow from the NE, site of the Miocene vents, to the SW. After cautioning his audience to look at these data with a grain of salt, Hearn showed that δ18O values of these waters can be used to time the Cascade uplift. Bruce Doe had a vocabulary question during the talk. Seyfried, Helz and the same anonymous had questions later.

     President Brett adjourned at 10:02 pm, which awakened a former president of GSW, caught sleeping against the wall. One hundred and seventeen other people attended.

     [signed Margo Kingston]

 

Geological Society of Washington - 1147th Meeting

January 22, 1986

     President Brett called the 1147th meeting of the Geological Society of Washington to order at 8:05 pm. The minutes of the previous meeting were read and corrected. New member, Jill Harvey was presented and four visitors were introduced. Suspicious of the sparse attendance after only one meeting with new officers, President Brett invited members to share taped versions of the Planet Earth series so that TV devotees would attend GSW for a live and really earthy performance. A suggestion from the floor that GSW might be taped was ignored, but our President's impassioned pleas for early dues payments, generous donations and desperately needed informal communications prompted Dave Stewart to suggest that Brett already sounded like public TV.  Undaunted, Robin continued with praise for the outgoing program chairperson, Dan Milton and announced his successor, Elaine Padovani. A rash of narcolepsy among attendees possibly related to beer consumption spurred a member to question whether attendance numbers should include consciousness as well as physical presence. Jane Hammarstrom then alerted us to a mild epidemic of kleptomania as order forms for GSW tee shirts are disappearing at meetings; without orders being returned.

     Our first speaker, A.J.W. Gerrard who is a geomorphologist not a geologist, gave a paper entitled, "Rock control in the granite landforms of southwest England". We learned of tors, growan and grus and how local variations in texture, joint orientation and spacing are crucial to weathering differences and development of landforms within the same basic rock (did he mean acid? You have to watch these geomorphologists.) Overall joint orientation of these Hercynian granites may be related to thrust direction and stress fields. Dan Milton asked why cowboy movies are made in granite terrains like those in England. Has Milton seen only spaghetti westerns made in Europe? High class cowboy movies are filmed at Monument Valley. Other questions by Hatch, Doe, Zen and Brett.

     Our second speaker, Richard Benson spoke of the "search for the ancient Straits of Gibraltar". As he is not a structural geologist, he described the paleontological evidence for the abrupt transformation from a shallow sea to a deep ocean basin, thus precipitating a catastrophic flow of Atlantic waters into the Mediterranean. This spectacular Pliocene waterfall did not take space in the Hispanic peninsula so our speaker took us on a fabulous mystery tour of Morroco, in search of evaporite/deep sea sediment contacts. He whetted our appetites for Moroccan geology not only with slides of wondrous Lawrence of Arabia landscapes but by describing a lithosomal nappe as a real porridge and another outcrop as a stew with pepper. We missed the couscous. Questions by Cronin, Rankin, Zen, Fiske and anonymous.

     John Ferry, a petrologist, not a hydrologist presented a paper entitled, metamorphic hydrology at 13km depth and 400 to 500°C. Clues to fluid flow in calc-silicate rocks can be found in the distribution of minerals such as wollastonite and map patterns of fluid/rock ratio indicate the degree of channelized fluid flow. Increased metamorphic grade means less channelization and more pervasive flow. Wasn't Alice's Restaurant filmed on calc-silicate rocks? Questions by Helz, Rumble, Milton, Stewart, Candela, Zen, Doe and a low voiced anonymous.

     The meeting adjourned at 10:10 pm, with 73 attendees, including one sleeping bear and an average of three sleeping humans.

     [signed Margo Kingston]

    

Geological Society of Washington - 1148th Meeting

February 12, 1986

     President Brett called to order the 1148th meeting of the Geological Society of Washington at 8:08 p.m.. New member, Janet Crampton of the AGI was announced and three visitors were introduced, including our third speaker, Craig Nicholson. Attendees stood in silence after Brett informed us of the deaths of Bill Menard, past Director of the USGS, and Allen H. Nichal, a member of GSW. The meeting continued with several announcements. The score is now 110 to 9; one hundred and ten missing GSW tee shirt order forms to nine orders. Also, volunteers are needed to judge at local Science Fairs. Why not wear the tee shirts while judging? Not only is April, Boy Scout Geology Badge month but April 20 is Geology Day in Fairfax County and members were urged to observe these events. Members were also asked to donate educational geology slides to schools. Our president told us to refer any questions regarding earth science education donations to Leanne and Dan Milton, who as of Feb 12, were listed in the telephone book.

     First speaker, John Sutter, who may be the fastest gun at the USGS, gave a talk entitled, "laser probe argon-40 to argon-39 dating of single mineral grains in situ". In order to degas material for argon determination, Sutter lines up pre-irradiated 2mm thick disks and fires away, putting as many as 50 shots into a single biotite grain in a minute and one half! Melt pits must be the proper diameter and depth, and speed is essential to maintain the near perfect vacuum. Sharpshooter Sutter makes apparent age determinations on minerals as young as 28.2 my. Applications include studies of slaty cleavage generation, zoned amphiboles and timing and nature of diagenesis of authigenic feldspars. Our speaker mentioned a new mineral, "age-wise-hornblende"; or in petrologic German, das Alterweisehornblende. Questions by Freeborne, Sorensen, Zen, French, Robertson, Doe and Brett.

     Second speaker, Tom Wright regaled us with slides of a perfect summer vacation spot, while illustrating his talk entitled, "folding and cleavage development in the Meguma terrain, Nova Scotia". Stages of deformation are well exposed in these seaside rocks. With compression, folds buckled and were amplified, then preferentially sheared with development of shear fractures. En echelon veins show the different shear directions. Petrologic beachcombing is rewarded with sand volcanoes which look like sand dollars, and worm-tube-like structures which occur along planes of cleavage. There were two anonymous questioners.

     Third speaker, Craig Nicolson, gave a talk entitled, "deformation along the southern San Andreas: twisty blocks and left-lateral faulting". He began by stating that his slides were not for kids, and he was right, especially California kids. They may be blissfully unaware of the number of microearthquakes occurring on secondary left lateral faults transverse to the major right lateral transform boundaries. Lurking between the San Andreas and San Jacinto systems are east/west lineations of seismic activity. At Bramley, aftershocks caused most damage where these seismic lines of microquakes intersected with the major Bramley seismic zone. Questions by Wright, Sorensen, Robertson, Zen and Candela.

     President Brett reminded us of our homework; more tee shirt orders, more informal communications and mostly dues, then adjourned the meeting at 10:08 p.m.  Attendance was 110.

     [signed Margo Kingston]

 

Geological Society of Washington - 1149th Meeting

February 26, 1986

     President Brett called the 1149th meeting of the Geological Society of Washington to order at 8:07 pm. After the minutes were read and approved, three visitors, Willy Accame, Michael Max and Allen Wilson were introduced. As usual, Brett exhorted us to pay our dues, and to buy tee-shirts. After Ray Rye called for volunteers to serve as Science Fair judges, Brett suggested that this provided an opportunity to advance one's child at school. Upon hearing that there were again no informal communications , Brett threatened to lash attendees to their seats in the Powell auditorium until someone volunteered. That might have led to some lively and very informal communication indeed, but scientific quality would have been suspect.

     Steven Shirey, our first speaker, gave a talk entitled, "Small scale, three component isotope heterogeneity in the mantle sources for mid-ocean ridge tholeiites". In his field area, about 14km of the North Atlantic ridge near the Azores, there is considerable diversity in trace element and isotopic composition. Two tholeiite lavas are LREE enriched, while a third is less enriched. Isotopic data for neodymium and strontium show a substantial range. The lavas have low 207Pb/204Pb and 206Pb/204Pb comparable to Archean lithosphere. These isotopic properties are incompatible with a simple plume hypothesis. Shirey interprets this heterogeneity to be the result of the mixing of portions of continental lithosphere into the asthenosphere. Questions by Stewart, Boyd, Haugerud, Accame, McClellan and Brett.

     Lucy McCartan, our second speaker, lugged a huge clock onto the stage but gave it nary a glance during her well timed talk entitled, "Factors controlling biogenic silica fixation in the sedimentary record: an example from the Miocene-Pliocene Chesapeake group." The Miocene was an exciting time, as both igneous activity and diatoms flourished. Then as now, conditions necessary for the production of diatomaceous sediments included the availability of nutrients, proper temperature and pH, a paucity of carbonaceous and terrigenous suspended sediments, and diatoms more wily than the grazers who seek to devour them. Usually upwelling ocean currents transport necessary diatom nutrients but along the east coast, detached cold water eddies off the Gulf Stream may have provided the mechanism for nutrient transfer. These eddy blips may have arrived at biweekly intervals resulting in a short amplitude diatom bloom, which outsmarted the ponderous grazers, resulting in extensive diatomaceous sediment outcrop as seen at Pope's Creek on the Potomac river. Questions by Rankin, Stewart and Stifel.

     Third speaker, Mark Gettings continued the McCartan mighty Miocene show with a talk entitled, "Relationship of young mafic plutons to seismicity in the eastern United States". He reinforced many geological prejudices, by showing a typical set of geophysical data: heat flow, gravity, aeromagnetics and correlating these data with geological data that he implied were near Charleston, South Carolina; later he confessed that this geophysical map was really in Saudi Arabia. Having completely destroyed our confidence, Gettings developed a model in which intrusion of a mafic pluton is followed by cooling with correspondent heating of the country rocks and hydrothermal alteration. This leads to thermal weakening of the host rocks, which then become a focus of earthquakes activity. And indeed the geophysical data suggests that there are buried mafic intrusions associated with seismically active areas in the eastern U.S. The authors then suggested that abundant intrusions and diatom blooms were effects of the same cosmic events, though they were not obvious. Both authors took questions by Rankin, R. Helz, Segovia, Greyhorne, McLaughlin, Brett and a comment by Sato.

     After giving us the same old homework, tee shirts, informal communications, science fairs and dues, President Brett adjourned the meeting at 9:50 and 41 intrepid attendees rushed out into the snowy night.

     Respectfully submitted,

     [signed Margo Kingston]

 

The Geological Society of Washington - 1150th Meeting

March 12, 1986

     First Vice-President Fiske called the 1150th meeting of the Society to order at 8:03 p.m. The minutes of the previous meeting were read and approved. The acting Secretary then read the names of two new members, and the one actually present, Marge Summers, stood and was applauded. Next E-an Zen announced that we still needed science fair judges and that sign-up sheets would be posted at the back of the room.

     Then, to celebrate the absence of President Robin Brett, we had an informal communication from Bruce Doe, on the subject of what acid rain is doing to downtown D.C. It's dissolving DAR Memorial Hall, The Red Cross building and the Jefferson Monument (built of Shelburne marble from Vermont), and the Pan American Union building (Georgia Marble). The Lincoln Memorial, by contrast, is falling apart on its own, with dilational cracks opening up in response to release of stress in the Yule marble subsequent to quarrying. Question by E-an Zen.

     The first speaker of the evening was David James, of DTM, speaking on "Earthquake Reflection Seismology: Results from Borah Peak, Idaho Aftershocks." In his presentation, James showed us the results of applying advanced seismic imaging techniques to the energy from small natural quakes instead of using that from controlled seismic sources. Major problems with this approach stem from the variable location and energy of natural quakes. Advantages include the fact that one can get larger, more energetic seismic sources, over a wider area; also, natural quakes are cheap and you don't have to file an environmental impact statement. James has looked at the aftershocks of the Borah Peak quake and concluded that, after the data were sufficiently massaged, he was getting coherent, geologically interpretable reflections over the range of the data array. Questions by George Helz, Gene Robertson and Dick Fiske.

     The next talk, by Rodey Batiza, was announced as being "A General Hypothesis for the Origin of Seamounts at and near Mid-Ocean Ridges," but the speaker informed us he wasn't going to talk about that. What he did want to talk about was the fine structure of the ridges, in particular their tendency to be segmented, every 30 km or so, by offsets of various sorts. He divided these offsets into several categories, the most memorable of which are the Small Non-Overlapping Offsets or "SNOO's," which is what he suggested the audience might be doing shortly. This 30-km segmentation was thought to reflect similar segmentation in the magmatic plumbing, with big MORB chambers centered in the segments, and lesser amounts of not-quite-MORB magma trickling through at the offsets, to form the small seamounts alluded to in the nontitle of the talk. Questions by Ralph Haugerud, E-an Zen (two), George Helz, Sorena Sorensen, and Bruce Doe, with a comment from Dick Fiske.

     The last talk of the evening was by I-Ming Chou, U.S.G.S., on the subject of the permeability of precious metals to hydrogen. The subject is of concern to the geologic community because of the widespread use of precious metals as containers for H2O-bearing materials and in conjunction with the use of various hydrothermal oxygen-fugacity buffers. H2 diffuses through palladium-silver alloys very quickly, through gold much more slowly. This data can be used to predict how long an fO2 buffer will be effective at a particular set of run conditions, and the minimum temperature at which a given metal or alloy can be used as a hydrogen membrane. Questions by Phelps Freeborn (2), George Helz, and Ralph Haugerud.

     Fiske adjourned the meeting at 9:45 p.m. There were 68 bodies in the room; no attempt was made to distinguish whether they were waking or snoozing.

     Respectfully submitted,

     [signed Rosalind Helz]

 

The Geological Society of Washington

March 26, 1986

     The 1151st meeting of the Geological Society of Washington was called to order by President Brett at 8:11 p.m. The minutes of the previous meeting were approved as read. Election of one new member, Craig Nicolson of the USGS, was announced. Robin Brett got right down tot he two major themes of his presidency, duds and dues. He lamented that so few members have followed his leadership in buying the GSW tee shirts, but noted that they may still be ordered through Jane Hammarstrom. An agitated Bruce Doe complained, "where is my tee shirt?" But our president assured him that he would soon have it in time for the warm weather. Members were again reminded of the present GSW fiscal crisis and urged to pay their dues immediately, despite our inability to cash the checks as the treasurer is out of the country. Janet Crampton, Chair of the Public Service Committee, described the need for Science Fair judges this spring and warned us not to leave without signing up for at least one of the Science Fairs.

     Felix Chayes of the Geophysical Laboratory gave the first talk, entitled "whatever became of descriptive petrography?" His two slides showed the decline of mineral and petrographic characterization of analyzed samples since 1920, although the number of analyses reported has soared. Thus geologists are blazing a novel trail out of the morass of specialization by learning less and less about more and more. Petrologists are failing to provide descriptions of mineral assemblages and modal analyses of the materials actually analyzed, while also failing to analyze for or report data on multiple valence states (of iron) and volatile contents. What is needed, says Chayes, is complete, unambiguous characterization of analyzed specimens. Fussy, fussy, fussy. Questions by E-an Zen, Bruce Doe, Joe Boyd, Phelps Freeborn, and Roger Nielson, who admitted to being guilty as charged.

     The second speaker, Daniel Jean Stanley gave a talk coauthored with Harrison Sheng entitled, "Discovery of Santorini volcanic ash in the Nile Delta: bearing of the Minoan eruption on biblical exodus events in Egypt." Stanley explained that for many years he has been studying sedimentary cores taken in the Mediterranean region usually from shipboard, but this talk would focus on work in the Nile delta, near Lake Mensawa, where cores are taken only along the roads so as to avoid setting off the land mines planted here and there about the countryside. The authors calculated that the coarse silt/fine sand fraction of the volcanic ash should have been transported to the Nile delta region by the devastating first eruption of Santorini 3500 years ago. Shallow drill cores taken there have yielded several dozen shards which fit the Santorini geochemistry: the same SiO2 refractive index, SiO2 to TiO2 ratios, and within the predicted size range. And there have been no volcanic eruptions in Egypt within recent times. The ninth plague described in Exodus was "darkness so intense that one can feel it, lasting for three days," and Stanley suggested that this darkness may have been the ash fall from the Santorini eruption. All 3 dozen shards, presumably. Questions by Dan Milton (2) E-an Zen, Phelps Freeborn (2) and anonymous (2).

     Julie Morris presented the third paper, "10Be evidence for sediment recycling in island arcs." She began by explaining why Be is an excellent sediment "tracker" in subduction systems as it is produced by cosmic radiation in the upper atmosphere, then deposited with rain and snow. The average surface sediment concentration of  10Be is 5 billion atoms/gram. With half-life of 1 1/2 my, only recent subducted sediments can be traced. High 10Be anomalies (3 million atoms/g) were measured in lavas from Chile suggesting that sediments were subducted to depth in the hot buoyant slab and transferred from the slab to the volcanic source. High 10Be was measured in lavas from the Kuril islands where a great quantity of sediment is fed into the trench. Intraplate and mid-ocean ridge lavas are depleted in 10Be; for example the average MORB concentration is 0.5 million atoms/gram. By the end of Morris' talk, there was not a Be skeptic in the house. Questions by Tony Segovia, Dan Milton, Bill Hauser, E-an Zen, Robin Brett and a compliment from Bruce Doe.

     Eighty-one people attended this meeting which was adjourned by President Brett at 10:10 p.m.

     Respectfully submitted,

     Margo Kingston

 

Geological Society of Washington - 1152nd Meeting

April 9, 1986

     President Brett called the 1152nd meeting of the Geological Society of Washington to order at 8:08 p.m. The minutes of the previous meeting were read and approved. Brett announced that he would quit bugging people to buy G.S.W. teeshirts, but would continue to nag about paying dues. Dick Fiske then announced that we need one more judge for the Montgomery County science fair, and several guests were introduced, including David Smith McGill of NBS, and Peter Johnson and George Varens(?) of JV Associates.

     The first talk of the evening, by Robert Wesson of the U.S.G.S., was on "Modeling the Rheology of Active Fault Zones." He described the phenomenon of afterslip, as observed in connection with the 1975 Oroville quake. Although the quake was quite large, and the aftershock pattern defined a west-dipping normal fault, no surface break appeared until several months after the quake. The fault was later intersected by drilling, suggesting that this belated surface breakage was indeed produced by slow creep on this same fault as the displacement from the quake propagated slowly through a near surface layer of crushed and weathered rock. Wesson illustrated this drilling with a shot of a drill rig, of which he said, "I cannot tell a lie. This well is in South Carolina. I included it because it seems to be important to show field stuff." Questions and discussion, much of it skeptical, from Johnson, Tilling, Stewart and E-an Zen. In response to harassment from Stewart and Zen about the paucity of data on ground breakage immediately after the quake, etc., Wesson conceded, "I of course would have preferred instrumental measurements and not to have to use geologists." Typical seismologist. Moto Sato then received a much-needed tutorial on basic elastic strain theory. The discussion closed when Keith McLoughlin asked a seismology-type question, and received a seismology-type answer.

     The second talk, "Geology and Tectonic Significance of the Ross Lake Shear Zone" was by Ralph Haugerud, U.S.G.S. The Ross Lake shear zone separates the low grade Hozameen eugeosynclinal sequence from the high-grade Skagit gneiss. The juxtaposition of dissimilar rocks and metamorphic grades gives a very tight apparent thermal gradient across the shear zone. Haugerud's preferred model for the area calls for differential uplift, during the Eocene, to thin the intermediate thermal zones and juxtapose the high and low-temperature ends of a Barrovian metamorphic sequence, as opposed to blaming it all on accretion of contrasting terranes. Questions by Walt Kavilius, Sorena Sorensen, Robin Brett, Eileen McLellan, Moto Sato and E-an Zen.

     The last talk of the evening, by Dmitri Sverjensky of Johns Hopkins, was entitled, "A Model for the Origin of the Metal Ratios of Sediment-Hosted Base Metal Sulfide Ore Deposits." These deposits appear, from extensive evidence, to form when connate fluids, both brines and hydrocarbons, migrate out of subsiding, compacting sedimentary basins. The metal ratios in the subsequent deposits depend to a significant extent on the nature of the rocks through which the brines migrate, with Zn-rich deposits associated with carbonates, Pb-rich with reducing sandstones and Cu-rich deposits with red bed-evaporite hosts. Questions by George Helz, Moto Sato (2), Roger Stoffregen, Peter Johnson, and Robin Brett.

     Brett closed with two announcements, and adjourned at 10:03 p.m. The attendance was a sparse 53.

     Respectfully submitted,

     [signed Rosalind Helz]

 

Geological Society of Washington - 1153rd Meeting

April 23, 1986

     Vice President Fiske called the 1153rd meeting of the Society to order at 8:04 pm. The minutes of the previous meeting were read and approved. Tom Hoering then presented a visitor, Francoise Becquard. Gene Robertson reminded all present of the May 3 GSW field trip. Jane Hammarstrom reported that she had submitted orders for GSW T-shirts. The acting secretary then read a series of announcements from Leanne Milton including the news the Charlie Milton would be 90 years old on April 25.

     Next E-an Zen delivered a short communications on "Joints in Montana." The patterns of joints observed in glaciated valley walls versus joint patterns outside glaciated regions in his study area are different. This led Zen to suggest that some of the extra joints seen in glaciated regions were produced by unloading 100 m of rock during glacial erosion. He noted, however, that the inferred stresses involved were much smaller than those needed to fracture rock under laboratory conditions.

     A second short communications (why do they come in pairs?) by Cyril Galvin addressed the problem of producing soot in deep-sea sediments. It seems that marine clays from near the K-T boundary contain little fluffy carbon particles, in addition to iridium, dead dinosaurs and other debris. The carbon particles were duly cited in an article in Science as evidence for worldwide forest fires at the time of the K-T extinctions. Galvin showed pictures of black grunge on the beaches of New Jersey, which were observed the day after the Garden State Racetrack burned down. Further examination confirmed that the grunge was indeed soot, and that it occurred downwind from the Garden State massive extinction. Galvin invited the audience to conclude that it seems unnecessary to invoke worldwide forest fires to explain the presence of a little soot in marine clays.

     The first formal talk of the evening, on "Vesicle and Olivine Phenocryst Distribution in Kilauea Iki Lava Lake, Hawaii" was given by Margaret Mangan, U.S.G.S., Reston. She presented data showing that vesicle and olivine phenocryst content declined in parallel in the upper 30 m of the lake, as the molted lake degassed and the olivine phenocrysts settled. Apparent settling rates for olivine are many orders of magnitude lower than would be predicted from Stokes' law, an observation that led Mangan to infer that the melt in the lake had the properties of a Bingham plastic, with a finite yield strength, rather than those of a Newtonian fluid. Questions by Jo Laird, E-an Zen, Felix Chayes, Warren Wood and Dick Fiske.

     The second talk was "Acid-Sulfate Alteration and Au-Cu-Ag Mineralization at Summitville, Colorado." The speaker, Roger Stoffregen, began by quoting Mark Twain, who once wrote that "A mine is a hole in the ground owned by a liar." Stoffregen neglected to say whether the Summitville deposit illustrates Twain's maxim or not. What the deposit does illustrate is acid-sulfate alteration, a relatively rare type having alunite and kaolinite as alteration products, surrounding an intensely leached core. This core, described by Stoffregen as the "vuggy silica unit," is where the Au-Cu-Ag mineralization occurs. The mineralization is there, hypothesized Stoffregen, because later hydrothermal fluids were channelized into this very open, vuggy rock. The only comment was by Tom Dutro, who rose to object to the use of the word "cartoon" in connection with geologic diagrams and sketches, presumably on the grounds that they aren't funny.

     Anne Hofmeister gave the final talk of the evening, entitled "Spectroscopic Determination of Thermodynamic Properties of Olivine at Mantle Pressures." Hofmeister and coworkers have studied phase transitions in forsterite bulk composition and tried to determine the thermodynamic properties of all its polymorphs, the goal being to be able to calculate the earth's geothermal gradient at great depth. The author fielded questions by Ben Burton (finished his comment with "You're wrong"), Robin Brett, Gene Robertson and Mary Ann del Marmol.

     The meeting was adjourned at 9:40 pm. Attendance was 65.

     Respectfully submitted,

     [signed Rosalind L. Helz]

    

GEOLOGICAL SOCIETY OF WASHINGTON - 1154th MEETING

SEPTEMBER 24, 1986

     The 1154th meeting of the society was called to order by President Brett at 8:12 p.m. The minutes of the previous meeting were read and approved as amended. Twelve guests were introduced. Four new members were announced, and one of these, Phil Berger was present. As has become the custom there were no informal communications, as President Brett was presiding. After brief complaints and entreaties about this, Brett announced that the evening's program would be especially entertaining to the paleontologists, stratigraphers and eclectic petrologists in the audience.

     The first talk of the evening, entitled "Early history of the southern Oklahoma aulacogen" was given by Charles Gilbert of the DOE. Located at the margin of the Texas craton [perhaps the world's smallest craton], the aulacogen is a fault-bounded horst which started out as a graben. Subsequent uplifting and erosion of this block exposed layered granite and rhyolite sheets and underlying mafic rocks with cumulus layering. Extension and tectonism accompanied the intrusion of the mafic liquids. The geochemistry of the igneous complex is consistent with that of a transitional tholeiitic rift zone. Gilbert contended that the Oklahoma aulacogen would be an excellent site for deep drilling. For now, it is a good place to enjoy a Permian landscape the way it really was. Questions by Tom Wright (of NSP), E-an Zen, Doug Rankin and Dick Tolchin.

     The second speaker, Bill Orr of the N.S.F., and a former student of Charles Gilbert, gave a paper entitled "Tertiary stratigraphy of the Pacific Northwest". The primary goal of this study was to interpret the paleoenvrionment of the Butte Creek area in Oregon where Oligocene sediments are interdigitated with younger volcanic rocks. Orr proudly showed slides of a Rube Goldberg type contraption, a mass of coiled rubber hoses, swinging pails and metal pipes, which he used to obtain drill core. Butte Creek sediments form a regressive sequence with shelf and high-energy marine deposits overlain by dune deposits intertongueing with offshore sediments, and non-marine sediments topping it all off. The ubiquitous fossil material ranged from the outer neritic, through littoral, tidal and forest biofacies. For the eclectic petrologists he described a talented echinoderm which could discriminate ilmenite and magnetite from quartz. Questions from Tom Dutro, Robin Brett and E-an Zen.

     Steven Stanley of Johns Hopkins University, gave the final talk of the evening, entitled "Evolutionary stability of Neogene bivalve species". While waiting for the projectionist to get organized, Stanley tossed out a few pearls of wisdom on the differences between the punctuational and gradualistic theories of evolution. For this beachcomber's dream study, Neogene and modern shells representing four families are photographed, the images projected, and these planar shapes digitized. The resulting stick figures yield nearly 43,000 individual measurements. It seems the punctuational model best represents the evolution of these bivalves as they zigzag through time. There is little change in 17 million years for some lineages and some shells rare today were also rare in the past. Questions by Peter Prinz, Ben Burton, Bill Hauser, E-an Zen and Phelps Freeborn.

     Before adjourning the meeting, President Brett describing a letter from a past Bradley Award winner who praised the wonderful taste of beer drunk from the Tiffany silver Bradley cup. The meeting was adjourned at 10 pm. Seventy three persons attended.

     Respectfully submitted,

     [signed Margo Kingston]

 

Geological Society of Washington

1155th Meeting

October 8, 1986

     The 1155th meeting of the Society was called to order by President Brett at 8:06 pm. The minutes of the previous meeting were approved as read, and several guests were introduced, including Tod Lenagh, Bill Wycoff, George DeNeve, Jill Nesterly, and Sergee Jostikov (sp. uncertain). Brett then announced that we (GSW) were at war with the Cosmos Club. Brett had refused to pay the full projectionists' fee for the previous meeting, because of the man's utterly abysmal performance. The club in turn did not bother to provide a projectionist at all for the October 8 meeting. Phelps Freeborn volunteered to man the projector, and did an excellent job. (But will Brett pay him? Don't bet on it.)

     Brett then asked if there were any informal communications, and, when informed there were none, said "Oh, that's right. I'm in town." Where had he thought he was?

     The first formal talk of the evening, by Melville Dickenson of VPI, was entitled "Iron Redox Equilibria in Peraluminous, Metaluminous and Peralkaline Silicate Melts." Dickenson has studied the variation of the ferric/ferrous ratio with melt composition, and finds that ferric iron is stabilized in peralkaline melts, while ferrous is stable in metaluminous and peraluminous melts, at constant SiO2 content and oxygen fugacity. The solubility behavior of other components, such as P2O5, TiO2 and ZrO2 also depends on whether the melt is peralkaline or peraluminous. This clearly-delivered talk elicited much discussion, with questions from Ken Towe, Moto Sato, E-an Zen, Dick Tollo, Bill Hauser, Zen again, Phelps Freeborn, George Helz, and, again, Sato. In response to one of Zen's questions the speaker replied that as far as he was concerned "boron can do anything it wants to do."

     The second speaker, Scott Wing of the Smithsonian, spoke on "Interaction of Vegetation and Sedimentation." The speaker, invited by President Brett to give his own vita, informed us "I was born in a log cabin and the reason I'm not in American Men and Women of Science is that I'm neither." (Is the Cosmos Club ready for this?) Moving on to his talk, he pointed out that two patterns of vegetation succession could be observed in the modern environment: In the first type, one plant community supplants another, each community modifying the environment in ways that favor its eventual displacement. In the second type, exemplified by bald cypress swamps, the plants modify the environment in ways that prevent other plants from moving in. This happened in the Eocene, too, according to the speaker. The normal, progressive type of plant succession is shown by the Willwood Formation in N.W. Wyoming. Further east, in the Bighorn Basin, one finds thick coals, formed in stagnant backwater swamps, by retrograde veggies of the second type. Some things never change. Questions by Mike Peruker, Ken Towe, Bill Hauser, and of course, E-an Zen.

     The last speaker of the evening, Randall Parrish of the Geological Survey of Canada, addressed us on "U/Pb zircon geochronology - new techniques, et cetera" in preference to the topic listed on the written announcement. Parrish began by saying how glad he was to be in Washington, DC, home to John Wesley Powell, one of his lifelong heroes, and also to world-class zircondater Tom Crowe. He declared that zircon is the world's most interesting mineral, a fact hitherto unknown to many of us, and proceeded to make a surprisingly good case for it. Basically, once a zircon crystal forms, it remains a closed system, so that isotopic ratios produced by radioactive decay of various U isotopes are never reset, unless the crystal dissolves completely. New techniques, allowing investigators to date parts of complexly zoned crystals, enable them to get ages of protoliths, metamorphic events, shearing, etcetera. Zircons have total recall. Questions by Sorena Sorensen, Gene Robertson, somebody who sat next to Gene Robertson, Dick Fiske, Moto Sato, Robin Brett, and Hatcher (?).

     Brett then told the membership toe were in good financial shape, announced the next meeting, and adjourned at 9:55 pm. Attendance was 63.

     Respectfully submitted,

     [signed Rosalind Helz]

 

Geological Society of Washington - 1156th Meeting

November 5, 1986

     The 1156th meeting of the society was called to order by President Brett at 8:05 P.M. Minutes of the previous meeting were read and approved. Two new members were announced and one guest, Jeff Tuttle was introduced. President Brett reported the death of GSW member, Wayne Sigleo. Attendees were reminded of the up-coming Piedmont GSW field tri p to the Alexandria-Occoquan Piedmont led by Avery Drake. Hopefully the IRS was not listening as Brett advised members that to pay future GSW dues this year [with the idea of deducting it on 1986 returns] may be illegal but urged us to do so anyway. Brett next took on the Cosmos Club. Due to sloppy Cosmos visual-aid services society members will now do the projecting at meetings, and save money. Volunteers were solicited. Bribes were mentioned. Brett next questioned if the recent low attendance at meetings was due to the current officers, parking anxiety or those awesome miles stretching between Reston and the Cosmos Club. Nobody mentioned the beer.

     E-an Zen leaped to the podium and presented the first informal communication with President Brett presiding. Zen spoke about S and I granites, aluminum and cordierite. He stated that the absence of cordierite in peraluminous granites may not mean that the granite is not S-type. Cordierite formation depends on the iron to magnesium ratio, the degree of hydration, oxidation, and sulfidation as well as alumina saturation. Dave Stewart asked a question.

     Startled by this surprising short communication, President Brett awarded the first formal speaker, Eric Sundquist an 8 year post doc appointment in his introduction. Sundquist, whose talk was entitled "fossil fuel carbon dioxide in a geological context" secured the attention of his audience by stating right off that there are megabucks available for the study of the partitioning of CO2 between oceans, atmosphere and the biosphere.

     Sundquist discussed results of his earth, air and water modeling to determine the carbonate horizon saturation and flux at the sediment/sea water interface. He stessed the important contributions geologists can make in this type of interdisciplinary study because of their understanding of carbonate distribution through time as well as the disparity between geotime and the sort span of anthropogenic effects. Questions by Dave Stewart, Phelps Freeborn, Robin Brett, Dan Milton, Ben Burton, Janet Crampton, Doug Rumble and George Helz.

     Second speaker, Craig Nicholson began his talk entitled "The North Palm Springs earthquake of July 8, 1986" by claiming that his slides were all wet, due to the heavy rainfall, that is, not their content.

     This earthquake caused localized surface deformation, such as rock falls, slumping and ground cracks to the tune of $6 million damage. Compressional features occurred complimentary to tensional fractures but there was little true tectonic displacement. Surface damage was not tectonic because rupture was at depth and probably occurred on the Banning fault, not the Mission Creek fault, site of most damage. It had been assumed that the 1948 earthquake was located on the Mission Creek fault but modern seismic studies put it between the two faults. In southern California they play epicenter hide and seek. Questions by Moto Sato (2), George Helz and Robin Brett.

     Craig Dietsch gave the final talk of the evening, entitled "hornblende 39Ar/40Ar age-spectra from high-grade rocks of the polymetamorphic highlands of western Connecticut". His study area, the Waterbury dame is among the largest is a series of domes within the Conn. River Valley. A decollment separating two major tectonic levels is exposed in this dome, but isograds are not coincident with the decollment. It seems hornblende collected above the decollment gives concordant spectra, and a good approximation to the age of metamorphism. Other horneblende is not so well behaved, yielding extremely discordant ages probably because extraneous argon is accumulated in retrograde events. This study has important implications for conventional argon dating, but Waterbury makes a person cynical despite the beautiful kyanite so Dietsch is ready to move on to more "normal" things.

     Questions from Dan Milton who asked Dave Stewart's question, Eileen McLellan, Serena Sorensen , E-an Zen (2), Ralph Haugeraud and Dave Stewart who thought of another question.

     President Brett thanked Phelps Freeborn for leaping into the breech and running the projector. Announced the new slate of officers and invited other nominees to run against these worthies at the next meeting.

     The meeting was adjourned at 10:08. Attendance was 60.

     Respectively submitted,

     Margo Kingston

    

THE GEOLOGICAL SOCIETY OF WASHINGTON - 1157TH MEETING

DECEMBER 3, 1986

     President Brett called to order the 1157th meeting of the Society at 8:10 P.M. Four new members, Kurt Panter, Royce Hanson, John Montague and Helen Long were announced, and one visitor, Randy Kusky, was introduced. An enthusiastic Dick Tollo gave us a preview of the report of the Best Student Paper Committee by describing the Committee's revitalization. As there were no further announcements nor informal communications, President-Elect, Dick Fiske, commenced his illuminating introduction of Robin Brett, as a South Australian émigré who burst forth from the University of Alidade (that's antipodal jargon for the University of Adelaide) to the laid back Harvard of the 60's, then on to a number of scenes in Washington, Texas and Reston, and finally to this esteemed podium.

     President Brett began his Presidential address entitled, "Volcanoes, sulfides and fluids from the Southern Juan de Fuca Ridge: a consortium approach", by describing how his interests shifted naturally from the Apollo Program to the inhospitable briny deep because he likes the consortium approach to solving geologic problems. After a brief plug for the upcoming JGR issue which will be devoted to the Juan de Fuca Ridge study, Brett outlined the project strategy: all available exploration tools are used to define the ridge before making a dive. Different cruises focused on a variety of anomalies associated with this system.

     But, why travel to the cold, fog, and rough seas off the Oregon/Washington coast when we have all that stuff right here in D.C.? Brett's answer: that the Juan de Fuca ridge has an active hydrothermal system which may be analogous to older ore-forming systems. Although this ridge does not have a rapid spreading rate, the extrusive rocks are sulfide enriched and have a significant economic potential. Moreover, the ridge is entirely within the U.S. exclusive economic zone. The glassy extrusive rocks contain clinopyroxene, plagioclase and olivine, but no pelagonite. They have no manganese crust and no sediment covering. Topographic highs are concordant, with high temperature anomalies. The ridge was mapped using a variety of geophysical methods including bathymetry, magnetics, gravity, heat flow, water temperature, echo sounding, VCR imaging, and photography. Video sweeps covered fifty yard swaths over 10 square kilometers. The magma chamber was delineated by multichannel seismic measurements. Beneath the waves lies a lava plain composed of multiple asynchronous flows which surround a nested graben bounded by en echelon faults. Collapse piles increase near the 5 or 6 hydrothermal vents which occur in the central cleft.

     Just as Brett got to the good part, where he was describing geologic traverses in the Alvin as comparable to traveling through utter darkness in a broom closet with a small window and a flashlight; suddenly our president was interrupted by a member of the consortium, Ellen Kapell, who wanted to provide more detail on a subject two slides back. It is the custom to not ask questions after the Presidential Address, but there is no precedent about setting the president straight during the course of his talk.

     Continuing with adventures in the Alvin, Brett pointed out that because the submersible can be navigated, it is possible to do geological mapping as well as to collect samples. With the help of excellent slides we journeyed through clefts dodging rock debris and aa-like flows. Close to the vents lurk what Brett described as furry/fuzzy rocks along with meter-sized crabs, and worm tubes which Brett initially claimed were up to 70 m in length! This estimate was subsequently revised to 7 m. Orthogonal chimney-like forms composed of sulfides loom in this murky landscape. Often, very fine dust obscures some of these wondrous features. Minerals collected near the vents include anhydrite, barite and margarite. There are two types of sulfides, those high in copper and zinc-rich; and, porous sulfides. Some vacant worm tubes bulge with marcasite and pyrite. A new mineral, a Zinc-sulfur-Clorohydroxide, was collected by Brett and studied by Howard Evans. The chemistry of this place is of course bizarre; the pH of the plume site is 3.2 and chlorine is high, precipitation at the plume is due to pH and temperature changes, as well as saturation.

     All too soon our journey beneath the sea came to an end. In deference to custcan, there were no questions. President Brett adjourned the meeting at 9:25 P.M., and despite his subjecting the audience to all that water, the approximately 120 thirsty attendees rushed to the refreshment table.

            Respectfully submitted

            Margo Kingston

            Recording Secretary

 

MINUTES OF THE 94TH ANNUAL MEETING OF THE

THE GEOLOGICAL SOCIETY OF WASHINGTON

DECEMBER 3, 1986

     Believing that members had recovered from the Presidential address and were well fortified against the rigors to come, President Brett called this raucous gang to order at 9:50 p.m. Before Brett could get in another word, Dick Tollo rushed the podium with his committee report but was firmly blocked by our president. Brett attempted a proper start again, but the meetings secretary tried an end run to get in her report first. No chance, because above all we follow Robert's Rules here. With calm finally restored, Rosalind Helz read the minutes for the 93rd Annual meeting. These were approved. The report of the meeting's secretary was decorously read. In the next report, Council secretary Helz gleefully told us that although only 50% of the council attended any of the three meetings, they were an effective bunch. They eliminated the finance committee and arranged for GSW to sponsor Leanne Milton's teaching guide while the Smithsonian put up the money.

     The Treasurer's report was read by Brett because Klaus Schultz had just left town. There must have been other reasons for his flight because the GSW financial situation had improved as a result of a dues increase and reduction of expenses. Suspicion rose again when the chairman of the auditing committee, Harvey Belkin, also failed to show. But the books were in order and the Treasurer was commended.

     Membership chairman, Fred Simon, reported that we lost only a few members in 1986 despite the dues increase. There was an increase in retired members. These mellow folk appreciate fiscal responsibility.

     Leanne Milton reported on the status of the pre-College education committee. Reportedly she caused 30,000 lbs of rocks to be moved from the USGS, making her the equivalent of a small glacier. Perhaps that explains the recent shifts and rebound in Reston. Geology day at a local Nature Center and the Naturalist Center at the Smithsonian also benefited from her efforts. Janet Crampton, Chairwoman of the Science Fair Committee, reported that 8 fairs were judged in a marathon series from mid-March through mid-April.

     Finally, Dick Tollo gained the podium with his report on the College Student Award committee. The undergraduate research award had been revitalized and he was optimistic about its benefits in setting youth on the right track. There were no takers in 1986.

     Gene Robertson reported on the work of the Centennial Committee. There were 29 founders of the society, all eminent scholars and authors of classic papers. Such a level of excellence should motivate college students and energize us all.

     When chairman of the Awards Committee, Steve Huebner, took the podium, waves of nervous tension swept the room. After noting that some of the scheduled papers should have been informal communications, Huebner announced that there were twin Great Dane awards for best actual informal communications. The honored recipients were acid rain foe, Bruce Doe, and Van Zen of the Montana joints. This committee sought to stimulate more informal communications by presenting two prizes. So far it looks like they lost on that one. Then came the Bradley prize announcements. The second best paper prize was also awarded to two, Julie Morris of 10Be fame and Charlie Gilbert of the OK aulacogen corral. Was this committee seeing double? It's fortunate that the society was in the money the way they were throwing the bucks around. These prizes have price tags. Steve Stanley stood alone at the top as winner of the first prize for his paper, "Evolutional Stability of Neogene Bivalve Species," which indeed combined scientific excellence with some interesting controversy.

     The 1986 embodiment of Sleeping Bear, Roz Helz, put on her third hat of the evening and displayed her raconteur skills. She revived the audience with yarns of the astonishing past of this gentrified cup and other GSW tribal myths. We were vividly reminded of the many moments of hilarity unconsciously provided by several speakers. The old pros in the audience sporadically supplied some comic relief too. But this committee was after a fresh display of "rarefied, goodnatured, fangless jollity." And what should happen? Cherchez the geophysicists. All this time paleontologists and geochemists have been embrace in an all consuming rivalry for science and wit, when its the geophysicists who were having all the fun. And so in the end, Rob Wesson was bestowed winner of the Sleeping Bear award and all it entails.

     President Brett read the slate for 1987 which was accepted by acclamation. Before handing over the gavel, he thanked all who had worked for GSW during his tenure and confessed that his greatest achievement while in office was leaving behind a "more submissive" Cosmos Club. Newly elected President Dick Fiske presented the new officers and adjourned the meeting.

     Respectfully submitted,

     Margo Kingston