Abstracts – 2011


Dr Thomas Strasser, the Emmons speaker, was stranded by a blizzard on the East Coast. His talk on “Crete before the Cretans: Palaeolithic Mariners in the Mediterranean” was presented in April. See below.



The Snowmastodon Site: Discovery, Science, and Initial Results

Dr. Jeff Pigati, USGS Denver, and Dr. Kirk Johnson, Denver Museum of Nature and Science

Abstract: In October 2010, construction crews working to expand the capacity of a reservoir near Snowmass Village, Colorado unearthed several bones of a juvenile Columbian mammoth. The discovery set off a frenzy of excavation and scientific efforts in which members of the Denver Museum of Nature & Science (DMNS) recovered more than 600 bones comprising parts of up to ten American mastodons, four Columbian mammoths, four ice age bison, two deer, a Jefferson’s ground sloth (the first recorded in Colorado), and several tiger salamanders. In addition to the vertebrate fossils, the site is host to exceptionally well-preserved plant, insect and aquatic invertebrate fossils – beetle parts are iridescent, plants are still green, and conifer cones are intact. The DMNS and USGS have partnered together in an enormous undertaking – to study the fauna, flora, and climate history of the Snowmass site in less than a year (the site will likely be underwater by November 2011). To date, several key research questions have emerged: (1) What does the Snowmass site, which is at 8874 feet above sea level, tell us about Pleistocene climate and biota at high elevations in the Ice Age Rockies? (2) What is the timespan represented by sediments at the site? (3) How and when did vegetation and climate change in the past? (4) What information can we ascertain regarding the ecology and life histories of the site’s mammoths mastodons, and other megafauna?
We will report on preliminary results of laboratory analyses (pollen, geochemistry, chronology) that are currently underway, and will also discuss the process of forming a team of top-flight scientists, what we/they plan to study, and what the results may tell us about past, present, and future life high in the Rocky Mountains.



Georg Petersen (1898–1985): Mining and Metallurgy in Ancient Peru

William E. Brooks

Abstract: Georg Petersen was born in Germany in 1898 and obtained his Ph.D. in geology from the National University of Kiel in 1922. He arrived in Perú in 1924 with a contract to manage the Zorritos oilfield, northern Perú. His extensive bibliography, published in a newly mastered language, includes research on copper, gold, petroleum, salt, and tin occurrences, as well as reports on the archaeology, botany, climate, and history of Perú.

In 1952, he began teaching economic geology at the Universidad Nacional de Ingeniería. Then, in 1970, with encouragement from archaeologist and friend, Duccio Bonavia, Petersen published Minería y Metalurgia en el Antiguo Perú. Petersen’s book, essentially a De Re Metallica for the New World, includes 10 chapters, extensive endnotes, 13 black and white figures, many of which are photographs taken in the field by Petersen, and 22 tables that provide forward-thinking archaeometric data on ancient gold, copper, silver, and platinum artifacts as well as analytical data on smelter scoria and other geoarchaeological materials from Perú, Bolivia, Chile, Colombia, and Ecuador. His book blends archaeology, art history, biology, Colonial exploration, ethnohistory, geology, metallurgy, and the mining technology of the ancient Andes. Publication of Petersen’s book, in English, as Geological Society of America Special Paper 467, will help spread his academic and applied knowledge of the importance and use of mineral resources in the ancient Andes to a broad new audience.



Crete before the Cretans: Palaeolithic Mariners in the Mediterranean

Dr. Thomas F. Strasser, Associate Professor, Department of Art and Art History, Providence College, Rhode Island

Abstract: A survey in 2008 and 2009 on the southwestern coast of Crete in the region of Plakias documented 28 preceramic lithic sites. Sites were identified with artifacts of Mesolithic type similar to assemblages from the Greek mainland and islands, and some had evidence of Lower Palaeolithic occupation dated by geological context to at least 130,000 years ago. The long period of separation (more than 5,000,000 years) of Crete from any landmass implies that the early inhabitants of Crete reached the island using seacraft capable of open-sea navigation and multiple journeys—a finding that pushes the history of seafaring in the Mediterranean back by more than 100,000 years and has important implications for the dispersal of early humans. (taken from Thomas F. Strasser and others, 2010, Stone Age Seafaring in the Mediterranean—Evidence from the Plakias Region for Lower Palaeolithic and Mesolithic Habitation of
Crete: Hesperia, v. 79, p. 145–190.)



Late Mesozoic to Cenozoic Rotation of the Colorado Plateau: Regional analysis of proposed Euler Pole Rotations from modeling and fault kinematic analysis

Dr. Timothy Wawrzyniec, Moncrief Chair of Petroleum Geology, Western State College of Colorado at Gunnison

Abstract: The late Mesozoic to Cenozoic tectonic evolution of the U.S. Cordilleran foreland is largely described in the context of the Late Cretaceous to early Tertiary Laramide Orogeny and the late Cenozoic Rio Grande Rift. Both tectonic regimes have been associated with tectonic models that require the Colorado Plateau to behave as a microplate that has relatively little internal deformation when placed in the context of strain found at the margins of the Plateau.

A critical test of tectonic models for the Late Cretaceous to early Tertiary Laramide Orogeny is whether plateau rotation models can produce an integrated strain field consistent with foreland geometries and kinematic indicators. Along the northern and eastern margins of the plateau, map-scale folds and arches show a concentric pattern of deformation with fold axes transitioning from NW–SE trending to N–S trending, respectively. Similar patterns are observed for fold features found within the plateau. Related minor fault analyses show a similar pattern of single stage shortening, except near the Sevier tectonic front where SE-directed shortening has been reported within and near the plateau. Evidence for Laramide-age rotation of the plateau is largely found in a measured increase in shortening strain along the eastern margin of the Plateau. The rotation was first described by competing models of Hamilton (1981, 1988) and Chapin and Cather (1981), which sparked an early debate about the importance of either a proximal or distal Euler pole for Laramide-age plateau rotation. To explore the consequences of rigid plateau models, a simple, but properly georeferenced, Euler pole model was used to predict strain fields associated with rotational Colorado Plateau models. Assuming a small rotation (~4°, which is not paleomagnetically detectable) and a proximal Euler pole, rotation of the plateau produces a pattern of finite shortening directions compatible with field observations. The model also clearly demonstrated that 10–15 km of dextral shear offset east of the plateau would produce 30–60 km of shortening north of the plateau. Moreover, if a distal Euler pole is assumed along with a more generous estimate of dextral shear of 25–40 km, then shortening of north of the plateau must be greater than 400 km. These results clearly favor a proximal Euler pole for Laramide-age plateau rotation and are permissive of established estimates of northwestward plateau rotation that ranges between 15–30 km of dextral offset along the eastern plateau margin (Wawrzyniec and others, 2007).

Following the cessation of Laramide compression, the U.S. Cordillera is known to have undergone widespread extension, which includes the onset of Rio Grande rifting along the eastern margin of the plateau as early as ~27 Ma. From a kinematic perspective, only one model exists to address the motion of the plateau during rifting. Chapin and Cather (1994) proposed an arbitrary Euler pole rotation of CW ~1.5° located in the eastern Uinta Range. This rift plateau rotation model is based on the arbitrary reclassification of rift related accommodation zones as sinistral strike-slip faults and definition of rifting by the onset of geologically sequestered rift-related sediments and volcanic rocks. The latter shows a progressive increase in age of rift sediments and volcanic rocks from north to south along the eastern margin of the plateau. A georeferenced test of this rotation is relatively inconclusive given the small amount of extensional strain on the rift but the standing Euler-pole model remains untenable if one considers the following: (1) the best studied accommodation fault zone (the Embudo Fault Zone) of the rift is not a left-lateral fault, rather it shows dextral shear to the west and sinistral offset to the east, which is offset consistent with scissor motion; and (2) given the kinematic modeling of the Laramide-age rotation, structures along the plateau margin where likely pure strike-slip along the southern part of the eastern margin and transitioned to nearly pure dip-slip near the northern margin. Such a strain gradient would likely have variable topography with increasingly higher uplifts along the eastern margin from south to north. If extension of the eastern margin began uniformly, then it is likely that the earliest rift basins would form in central New Mexico where topography was lower, which would give the appearance of larger extensional strains to the south. Ultimately, given the paucity of available fault kinematic data, an alternative rotational model cannot be established at this time.

Throughout the late Mesozoic and Cenozoic the Colorado Plateau has largely behaved as a microplate, or as a stress guide, that resulted in deformation far into the Cordilleran foreland. Although there is little agreement on the driving mechanism for such deformation, the foreland is clearly coupled to deformation within the Cordilleran hinterland and these strains are relatively small in comparison. Continued kinematic investigations of both Laramide and Rift related faults could only serve to improve our continued understanding of these complex, overlapping tectonic regimes.

Chapin, C.E., and Cather, S.M., 1981, Eocene tectonics and sedimentation in the Colorado Plateau–Rocky Mountain area, in Dickinson, W.R., and Payne, W.D., eds., Relations of tectonics to ore deposits in the southern Cordillera: Ariz. Geol. Soc. Dig., no. 14, p. 173–198.
Chapin, C.E., and Cather, S.M. 1994, Tectonic setting of the axial basins of the northern and central Rio Grande Rift in Keller, G.R., and Cather, S.M., eds., Basins of the Rio Grande rift—Structure, stratigraphy, and tectonic setting: Geological Society of America Special Papers, no. 291-I, p. 5–25.
Hamilton, W.B., 1981, Plate-tectonic mechanism of Laramide deformation: University of Wyoming Contributions to Geology, v. 19, p. 87–92.
Hamilton, W.B. 1988, Laramide crustal shortening, in Schmidt, C.J., and Perry, W.J., eds., Interaction of the Rocky Mountain foreland and the Cordilleran thrust belt: Boulder, Colo., Geol. Soc. Am., p. 27–39.
Wawrzyniec, T.F., Ault, A.K., Geissman, J.W., Erslev, E.A., Fankhauser, S.D., 2007, Paleomagnetic dating of fault slip in the southern Rocky Mountains, USA, and its importance to an integrated Laramide foreland strain field: Geosphere, v. 3, no. 1, p. 16–25.


Evolution Confers Morality

Matt Young, Colorado School of Mines

Abstract: Our sense of morality is neither supernatural nor mysterious but rather is an evolved trait. It is likely innate rather than learned or cultural. Cooperation exists at all levels in the animal kingdom, and many nonhuman animals display a moral sense. Kin selection shows how a moral sense evolved and why it is applied most strongly to relatives and associates. Morality has evolved — imperfectly as always, but it evolved.

Biography: Matt Young is Senior Lecturer in physics at the Colorado School of Mines, a regular contributor to the influential evolution blog The Panda’s Thumb, and president of Colorado Citizens for Science. His most recent book, written with Fairview teacher Paul Strode, is Why Evolution Works (and Creationism Fails). Formerly, he was a Physicist at the National Institute of Standards and Technology and held faculty positions at Rensselaer Polytechnic Institute and the University of Waterloo. He has published roughly 100 scientific papers and reports; written three books on optics, technical writing, and science and religion; and coedited the book Why Intelligent Design Fails.



Paleolithic Whodunit! Neanderthals, Homo sapiens and the Human Revolution‚ in Italy

Julien Riel-Salvatore, Department of Anthropology, University of Colorado, Denver

Abstract: The disappearance of Neanderthals has often been explained as the result of modern humans either exterminating or outcompeting them. This so-called human revolution‚ was said to be associated with new behaviors in Homo sapiens, including better toolmaking strategies, better hunting techniques, a broadening of their diet, the use of art and ornaments, and the development of far-flung social networks. Recent research in southern Italy upends this view by showing that some of these behaviors may have been developed independently by some of the last Neanderthals living in the area. This presentation will summarize this new evidence and explain what this means for current views of our relationship to Neanderthals in light of recent genetic and skeletal evidence. The conclusion that Neanderthals may not have been so different from us and its implications will close the presentation, along with an overview of ongoing field research.

Biography: Julien Riel-Salvatore is Assistant Professor in the Department of Anthropology at the University of Colorado, Denver. He was born in Montréal, Canada, earning his BA (first class honors) from McGill University there before attending Arizona State University where he received his Ph.D. in 2007. Following this, he was a Postdoctoral Fellow of the Social Sciences and Humanities Research Council of Canada for two years at McGill University, where he also lectured in the Department of Anthropology. In 2009, he moved to his current position at UC Denver, from where he continues his research on Neanderthals and the Paleolithic archaeology of Italy.

His research focuses on Neanderthals and the earliest Homo sapiens settlement of Europe. He has conducted fieldwork in Spain, South Africa, Ethiopia and the U.S. Southwest, but since 2003 his research has taken place mostly in Italy, a country whose distinctive geography makes it a unique archaeological laboratory to study larger processes, such as the disappearance of Neanderthals. His research showing that Neanderthals were able to innovate independently of Homo sapiens influence has recently been featured in the New York Times, the BBC and the Washington Post, in addition to being published in scientific journals including the Journal of Archaeological Method and Theory, Current Anthropology, and American Antiquity. Since 2008, with several Italian colleagues, he has also been directing a large-scale international collaborative excavation project at the Caverna delle Arene Candide in northern Italy, where prehistoric art and early modern human levels have recently been identified. Every year, this ongoing project provides students and volunteers with the opportunity to experience archaeological research first-hand.

He also blogs about his research and current news in archaeology and paleoanthropology at, A Very Remote Period Indeed, part of his ongoing efforts to make research on human origins understandable and appealing to as wide an audience as possible.
Julien lives in Denver with his wife Alejandra and their newborn son, Mateo.



Forming the Planets: What’s New with the Oldest Events in the Solar System

Dr. Bill Bottke, Assistant Director of the Department for Space Studies at Southwest Research Institute (SwRI) in Boulder, Colorado

Abstract: Dr. Bill Bottke, Director of the Center for the Lunar Origin and Evolution (CLOE) of NASA’s Lunar Science Institute, discusses several recent advances that are helping to rewrite the history of the Solar System as we know it. It was previously thought that our planets remained more or less in the same location as where they originally formed. New models, illustrated by Bottke’s animations, show how the gas giant planets dramatically migrated to new locations nearly a half billion years after their formation. This cataclysmic event scattered asteroids and comets throughout the Solar System and produced huge impact basins on the Earth, Moon, and Mars. Some of the Solar System’s most intriguing questions, such as when did life develop on the Earth, and when and where did Mars get its water, may be linked to this last critical phase of planet formation.

Biography: Dr. William Bottke is the Assistant Director of the Department for Space Studies at Southwest Research Institute (SwRI) in Boulder, Colorado. Dr. Bottke is also the Director of the Center for Lunar Origin and Evolution (CLOE) of NASA’s Lunar Science Institute. His research interests include the collisional and dynamical evolution of small body populations throughout the solar system (e.g., asteroids, comets, irregular satellites, Kuiper belt objects, meteoroids, dust) and the formation and bombardment history of planetesimals, planets and satellites. He is also interested in how near-Earth objects (NEOs) are delivered from their source regions in various asteroid and cometary populations to their observed orbits. He received a B.S. in Physics and Astrophysics from the University of Minnesota in 1988 and a Ph.D. in Planetary Science from the University of Arizona in 1995. He has also been a postdoctoral fellow at both Caltech (1996-1997) and Cornell University (1997-2000). He was awarded the Paolo Farinella Prize in 2011, the prize instituted in honor of Italian astronomer Paolo Farinella (1953–2000).



Tertiary Magmatism and Mineralization in a Complex Tectonic Environment, Southwest Utah—Initial Investigations

Lisa R. Fisher, Colorado Scientific Society 2011 President’s Address

Abstract: The Star Range of southwestern Utah is situated at the intersection of the western edge of the Colorado Plateau, the southern extension of the Sevier Thrust Belt, and the eastern margin of the Basin and Range Province. The range lies within the east-northeast trending Pioche Mineral Belt. This complex junction of features provided opportunity and pathways for Tertiary magmatism and related mineral bearing fluids to produce a series of gold, silver, and base metal bearing porphyry-epithermal deposits hosted by Paleozoic and Mesozoic strata.

The North and South Star Mining Districts and adjacent districts were opened ca. 1856–1870 and include some of the oldest mines in Utah. All of these districts historically reported high-grade gold, silver, copper, lead, and zinc deposits. More recently, tungsten, molybdenum, and possible tellurium have been identified. Early works (ca. 1913–1920) by B.S. Butler form a basis for modern geological studies in this area, along with more recent geologic mapping by Best, et al. (1989), Baetck (1969), and Baer (1966). However, much work remains to be done to fully understand the Star Range and its mineral deposits.
The Star Range contains two primary porphyry stocks: the Star Stock on the north side of the range, and the Vicksburg Stock on the east side. A third, more poorly investigated stock, near the ghost town of Shauntie in the southwestern area of the range, is the Moscow Stock. Both the Star and Vicksburg are complex stocks, with greater variation and a rough zoning occurring within the Star Stock. The main phases of the Vicksburg Stock were historically mapped on the basis of color and weathering, as either granodiorite or quartz monzonite phases. New detailed investigations reveal that there is much more quartz and potassium feldspar present than these classifications might suggest, and much less mineralogical difference between phases. Xenoliths are abundant and more mafic. The stocks are accompanied by three different compositions of dikes, identified as quartz porphyry, aplite, and late phase lamprophyres. Some of the “lamprophyres” of previous workers we have re-identified as contact metamorphosed calc-silicate intervals within sedimentary units.

New investigations on the Star Range have also revealed past interpretative errors. An igneous unit previously identified as intrusive granodiorite is now known to be composed of porphyritic andesite flows with definitive volcanic textures and structures such as flow banding, agglomeratic layers, and possible vents or fissures. The lowest flow contains abundant disseminated sulfides, and much of the unit has undergone propylitic alteration. A small outcrop of opal-bearing sinter indicative of surface or near surface hydrothermal activity occurs nearby. The attitude of the flows suggests either flow down a relatively steep slope, or tectonic tilting after deposition. Stream worn cobbles and pebbles of Permian Kaibab Limestone, Triassic Moenkopi shales, siltstones and limestones and possible Jurassic Navajo Sandstones are caught up in the agglomerate flows. Cross-cutting veins in one area contain copper mineralization.

Peak igneous activity in this region occurred ca. 31 Ma to 20 Ma, with rhyolites in the area as young as ~7.4 Ma. Following compressional stresses of the Late Cretaceous Sevier thrusting, extensional tectonics were dominant starting ~56 Ma. The region underwent at least four episodes of rotation as noted by changes of stress fields from NE-SW (169 to 31 Ma), to ENE-WSW at 30 to 25 Ma, to E-W at 22 Ma, and finally NW-SE at 14 Ma. These regional rotations are reflected on a local scale and influence the emplacement and faulting of mineral deposits, and thus are important to understanding deposits in context of exploration and development.

Mineral deposits result from multiple phases of emplacement. The most common ore types are vein/fissure-fills, chimney-mantos, silica breccias, and skarns. Deposits are controlled by igneous-sedimentary contacts, complex fault systems, and are also developed in porous and permeable zones within the Permian Kaibab Limestone and older Paleozoic zones. Tectonic influences, including basin and range style extensional faulting, subsequent regional rotation of the fault blocks, and association with thrust features of Sevier age, played an important role in developing the geometry of ore bodies in this region.

As our work continues, definite relationships between magmatic units, mineralization, structural/tectonic features, and their timing are becoming apparent. Both the Star and Vicksburg Stocks are polymetallic and carry gold, silver, copper, lead, and zinc, along with other minor minerals. The Vicksburg Stock carries the higher gold content, while the Star Stock appears to have higher associated copper. Epithermal vein deposits carry high lead-silver throughout the range. Silica breccia deposits marginal to the stocks test carry silver-antimony-gold. Numerous skarn deposits at the contacts between the intrusive stocks and Paleozoic limestones are silver-copper-gold-bearing. The aplite dikes, and especially the quartz porphyry dikes, are associated with higher gold areas. Much work remains to be done in this region towards more fully understanding the timing of mineralization with respect to phases of magmatism, and to determine structural/tectonic controls on magmatism and ore emplacement.