Dr. Thomas Yancey

Professor

University of California, Berkeley, Ph.D., 1971

Syracuse University, 1959-1962

Research specialty: paleontology

Research:

Environments of deposition of marine shelf and marginal marine strata; Invertebrate paleontology of molluscs (especially clams) and brachiopods; Stratigraphy and correlation (lithostratigraphy and chronostratigraphy).

Icehouse Paleontology

Molluscan biotas: The biotas of the Carboniferous and Permian are special because they contain abundant molluscs, which were common in both shallow water and deeper water settings (Yancey, 1978; Yancey & Heaney, 2000). Frequent changes in sealevel, generated by repeated change in Gondwanan icesheets, produced major environmental shifts and environmental instability that allowed opportunistic species to flourish. This especially favored molluscs, among which are the earliest representatives of many groups considered characteristic of the Mesozoic. The study of these groups is revealing the origins of groups dominant after the great extinction event of the end Permian.
Paleoceanography: A collaborative project (with Ethan Grossman and students) on the documentation of stable isotope stratigraphy of the Carboniferous and Permian, primarily by utilizing brachiopod shell carbonate (Adlis et al., 1988; Grossman et al., 1991, 1993, 1996; Mii et al., 1997, 1999, 2001). The project focuses on the icehouse climatic interval and the global warming that ended icehouse conditions. This work has produced detailed stratigraphies for the midcontinent of North America and Russian platform, both located on the Laurussian supercontinent during the late Paleozoic.
Unusual bivalves: My favorite topic is the study of unusal bivalves, an interest that has led to work describing two great groups of giant, winged bivalves: alatoconchids of the mid Permian (Yancey & Boyd, 1983; Yancey & Ozaki, 1986) and the wallowaconchids of the late Triassic (Yancey & Stanley, 1999; Yancey et al., 2005). Both groups are characterized by large size and broad flattened "wing" extensions of the shell - however, the two groups are homeomorphs and unrelated to each other. At the other end of the size range is an equally unusual group of praecardioid bivalves (Yancey & Heaney, 2000). Praecardioids are fairly common in deeper water environments, but many are poorly known and undescribed.

Eocene Paleoclimate. The warmest climates of the Cenozoic occurred during the early Eocene, only to be followed by rapid decline in global temperatures during the late Eocene, culminating in the appearance of continental ice sheets on Antarctica. Investigations of the extended record of late Eocene climate decline in the Gulf Coast involves recording changes in land vegetation (Yancey et al, 2003; Elsik & Yancey, 2000) and stable isotope determination of paleotemperatures in shallow marine shells (Kobashi et al, 2001). The nearshore, marginal marine strata of the late Eocene in Texas contain rich spore/pollen assemblages that document climatic changes consisting of progressive decline in temperatures and is used to bridge the climate records of open marine ocean basins with that of continental interior basins.

Paloegene Stratigraphy. Work on the Paleogene stratigraphy of the outcrop belt of east-central Texas, specifically in the Brazos River Valley, involves acquiring detailed descriptions of local sections to generate a lithostratigraphic, biostratigraphic, and chronostratigraphic framework for the area (Yancey & Davidoff, 1991, 1994). Most sediments were deposited in marginal marine environments, but carbonate has been lost due to diagenetic leaching. The section contains common lignite beds and several important volcanic ash layers. The results of this work have been summarized in several guidebook publications describing the stratigraphy and outcrops of the area and in reports on volcanic ash beds (Guillemette & Yancey, 1996; Yancey & Guillemette, 1998). A new project is directed at documenting shelf deposits of the Paleocene-Eocene Wilcox Group.
KT Boundary Deposits. The Cretaceous-Tertiary boundary deposits around the Gulf of Mexico have been described as products of unusual events and depositional processes. Ongoing work documenting the depositional history and processes of deposition of these sections in the northern Gulf region shows that secondary depositional mechanisms, such as debris flows, storm waves, and shelf turbidity flows are responsible for deposition of boundary complex sediments (Yancey, 1996; Heymann et al., 1996). It also reveals a long sequence of depositional events with repeated major energy disturbances. This work is reconciling various hypotheses about conditions present in the Gulf of Mexico during the KT event. Present work reveals that these distal deposits of the Chicxulub impact contain small spherule ejecta droplets formed from melts of silicate composition and accretionary lapilli of carbonate composition.

Projects:

Late Paleozoic Icehouse Paleontology
Late Paleozoic Isotope Paleoceanography
Exceptional bivalves
Eocene Paleoclimate
Paloegene Stratigraphy
KT Boundary Deposits

Experience:

Department of Geology, Texas A&M University, 1980-present, Professor.
T.E. Yancey & Associates, Pocatello, Idaho, 1978-1980, Consulting services.
Department of Geology, Idaho State University, Pocatello, Idaho, 1975-1980, Assistant Professor.
Department of Geology, University of Malaya, Kuala Lumpur, Malaysia, 1971-1975, Lecturer.

Publications:

Yancey, T. E., Stanley, G. D., Jr., Piller, W. E., and Woods, M. A., 2005, Biogeography of the Late Triassic wallowaconchid megalodontoid bivalves; Lethaia, v. 38, p. 351-365.
Hoare, R. D., Mapes, R. H. & Yancey, T. E., 2002, Structure, taxonomy, and epifauna of Pennsylvanian rostroconchs (Mollusca); The Paleontological Society, Memoir 58, 30 p.
Yancey, T. E., Elsik, W. C., and Sancay, R. H., 2003, The palynological record of Late Eocene climate change, northwest Gulf of Mexico, in Prothero, D. R., Ivany, L. C., and Nesbitt, E. A., eds; From Greenhouse to Icehouse - the marine Eocene-Oligocene transition, Columbia University Press, New York, New York, p. 252-268
Bandel, K., Nutzel, A., & Yancey, T. E., 2002, Larval shells and shell microstructures of exceptionally well-preserved Late Carboniferous gastropods from the Buckhorn Asphalt deposit (Oklahoma, USA); Senckenbergiana Lethaea, v. 82, p. 639-689.
Mii, H.-S., Grossman, E. L., Yancey, T. E., Chuvashov, B., & Egorov, A., 2001, Isotopic records of brachiopod shells from the Russian Platform: evidence for the onset of mid-Carboniferous glaciation; Chemical Geology, v.175, p. 133-147.
Yancey, T. E., and Heaney, M. J., III, 2000, Carboniferous praecardioid bivalves from the exceptional Buckhorn Asphalt biota of south-central Oklahoma, USA, in Harper, E. M., Taylor, J. D., and Crame, J. A., eds., The evolutionary biology of the Bivalvia: Geological Society, London, Special Publications v. 177, p. 291-301.
Yang, Z. and Yancey, T. E., 2000, Fusulinid biostratigraphy and paleontology of the middle Permian (Guadalupian) strata of the Glass Mountains and Del Norte Mountains, west Texas; Smithsonian Contributions to the Earth Sciences, no. 32, p. 185-259.
Mii, H-S., Grossman, E. L., and Yancey, T. E., 1999. Carboniferous isotope stratigraphies of North America: Implications for Carboniferous paleoceanography and Mississippian glaciation: Geol. Soc. America Bull., v. 111, p. 960-973.
Yancey, T. E., and Stanley, G. D., Jr., 1999, Giant alatoform bivalves in the upper Triassic of western North America; Palaeontology, v. 42, p. 1-23.
Yancey, T. E. and Guillemette, R., 1998, Major volcanic ash units in the Late Eocene of east Texas; Gulf Coast Association of Geological Societies Transactions, v. 48, p. 511-516.
Heymann, D., Yancey, T.E., Wolbach, W.S., Thiemens, M.H., Johnson, E.A., Roach, D., & Moecker, S., 1998, Geochemical markers of the Cretaceous-Tertiary boundary event at Brazos River, Texas, USA; Geochimica et Cosmochimica Acta, v. 62, p. 173-181.
Mii, H.-S., Grossman, E.L. & Yancey, T.E., 1997, Stable carbon and oxygen isotope shifts in Permian seas of West Spitsbergen - Global change or diagenetic artifact?; Geology, v. 25, p. 227-230.
Yancey, T.E., 1996, Stratigraphy and depositional environments of the Cretaceous-Tertiary boundary complex and basal Paleocene section, Brazos River, Texas; Gulf Coast Association of Geological Societies, Transactions, vol. 46, p. 433-442.
Guillemette, R. & Yancey, T.E., 1996, Composition and provenance of volcanic glass in Late Eocene Manning Formation, east-central Texas; Gulf Coast Association of Geological Societies, Transactions, vol. 46, p. 159-166.
Grossman, E.L., Mii, H.S., Zhang, C., & Yancey, T.E., 1996, Chemical variation in Pennsylvanian brachiopod shells - diagenetic, taxonomic, microstructural, and seasonal effects; Journal of Sedimentary Research, vol. 66, p. 1011-1022.
Yancey, T.E., 1995, Depositional trends in siliciclastic deposits of the Stone City transgressive systems tract, middle Eocene, Texas; Gulf Coast Association of Geological Societies, Transactions, vol. 45, p. 581-586.
Yancey, T. E., 1978, Brachiopods and molluscs of the Lower Permian Arcturus Group, Nevada and Utah. Part 1: Brachiopods, Scaphopods, Rostroconchs and Bivalves; Bulletins of American Paleontology, vol. 74, no. 303, p. 257-367.

Affiliations:

Additional Information:

Collections management of fossil collections, used for research and for teaching, is my concern. We currently have good research collections for Carboniferous & Permian marine invertebrates and Cretaceous & early Tertiary marine invertebrates & microfossils and we have very good teaching collections for Historical Geology & Marine Invertebrate Paleontology.

Giving to Geosciences - Texas A&M University - State of Texas