Stephen Pekar

Adjunct Associate Research Scientist
Lamont-Doherty Earth Observatory
Geochemistry
Fields of interest: 
Sequence stratigraphy, paleoceanography, Cenozoic cryospheric evolution of Antarctica, paleoclimatology, Holocene climate, sediment transport in estuaries

I am a geologist with research interests that encompass a wide variety of problems related to the oceanographic and climatic evolution of the late Cretaceous and Cenozoic. To tackle these problems, I develop sedimentological, microfossil, and geochemical data obtained from cores that were taken from estuarine, near-shore, and deep-sea environments. These are used to extract climatic, oceanographic, and eustatic (global sea level) signals at the decadal-, millennium-, to million-year scale.

I am a geologist with research interests that encompass a wide variety of problems related to the oceanographic and climatic evolution of the late Cretaceous and Cenozoic. To tackle these problems, I develop sedimentological, microfossil, and geochemical data obtained from cores that were taken from estuarine, near-shore, and deep-sea environments. These are used to extract climatic, oceanographic, and eustatic (global sea level) signals at the decadal-, millennium-, to million-year scale., My research uses a variety of techniques as well as the design of new methods, which facilitate a better understanding of the stratigraphic record. My research can be broadly divided into four groups. The first group combines projects that use a new method to constrain global sea-level amplitudes that I developed and then implemented for pre-Pleistocene records. This new method uses an integrated approach by combining lithofacies, age control (biostratigraphy, magnetostratigraphy, and Sr-chemostratigraphy), two-dimensional paleoslope modeling of benthic foraminiferal biofacies, and two-dimensional flexural backstripping to develop a high-resolution chronostratigraphic framework and to reconstruct the stratal geometry of the margin.

The second group of projects have been aimed at gaining greater insights into paleoceanographic, climatic, and sea-level changes during important warm periods in Earth's history: the early Miocene (21-16 Ma), late early Eocene to middle Eocene (51-42 Ma) and late Paleocene (59-55 Ma). These projects use stable isotopes and trace metal ratios to reconstruct past climates and paleoceanographic changes. , A third area of research is focused on developing a better understanding of the climatic history and evolution of the Antarctic continent from the Eocene (Greenhouse world), to the Oligocene & Miocene (icehouse world), and until Recent. To this end, I have become involved in the ANDRILL (ANtarctic DRILLing) Program, which "is a multinational initiative with the objective to recover stratigraphic core records for the use of interpreting Antarctic?s climatic, glacial, and tectonic history for the past 50 Ma". I am currently serving on the U.S. Steering Committee and will also be part of an expedition that will obtain seismic and gravity data in Southern McMurdo Sound for finalizing the two sites that will be drilled in this area in 2007. Finally, a fourth group refers to projects that are using a new integrated approach for using estuarine records to determine climate variability and environmental changes of the Hudson River region by estimating paleosalinity changes in the estuary for the past 7, 000 years.

  • Cryospheric Evolution during the Middle Miocene: Seismic and Stratigraphic Drilling of the Southern McMurdo Sound, Antarctica
  • Using New Tools to Explore Undiscovered Country: Understanding the Tectonic and Stratigraphic History of Offshore New Harbor, Ross Sea, Antarctica
  • Developing High-Resolution Isotopic Records for the Late Paleocene (61-55 Ma) from ODP Site 1259 (Equatorial Atlantic) and DSDP Site 215 (Tropical Indian)
  • Developing High-Resolution Climate Records for the NYC Water Shed and Sediment Transport in the Hudson River for the past 7,000 years
  • Evaluating Sea-Level/Ice-Volume Changes in the Greenhouse World of the Cretaceous: Resolving the Geometry of Offshore New Jersey Strata

 

Education
List of degrees from highest to lowest:
Ph.D. Geology
Rutgers, The State University of New Jersey, New Brunswick, NJ
1999
M.S. Geology
Rutgers, the State University of New Jersey, New Brunswick, NJ
1995
B.A.
Queens College, Flushing NY
1986
Honors & Awards: 
Outstanding Journal Paper in Journal of Sedimentary Research for 2003 June, 2005
Selected Publications: 
High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet in Antarctica, Pekar, S. F.; DeConto, R. M. , Palaeogeography Palaeoclimatology Palaeoecology, Feb 9, Volume 231, Issue 1-2, p.101-109, (2006), DOI 10.1016/j.palaeo.2005.07.027

Resolving a late Oligocene conundrum: Deep-sea wanning and Antarctic glaciation, Pekar, S. F.; DeConto, R. M.; Harwood, D. M. , Palaeogeography Palaeoclimatology Palaeoecology, Feb 9, Volume 231, Issue 1-2, p.29-40, (2006), DOI 10.1016/j.palaeo.2005.07.024

Glacioeustatic changes in the early and middle Eocene (51-42 Ma): Shallow-water stratigraphy from ODP Leg 189 Site 1171 (South Tasman Rise) and deep-sea delta O-18 records, Pekar, S. F.; Hucks, A.; Fuller, M.; Li, S. , Geological Society of America Bulletin, Jul-Aug, Volume 117, Issue 7-8, p.1081-1093, (2005), Doi 10.1130/1325486.1

Quantitative constraints on the origin of stratigraphic architecture at passive continental margins: Oligocene sedimentation in New Jersey, USA, Pekar, S. F.; Christie-Blick, N.; Miller, K. G.; Kominz, M. A. , Journal of Sedimentary Research, Mar, Volume 73, Issue 2, p.227-245, (2003)

Calibration between eustatic estimates from backstripping and oxygen isotopic records for the Oligocene, Pekar, S. F.; Christie-Blick, N.; Kominz, M. A.; Miller, K. G. , Geology, Oct, Volume 30, Issue 10, p.903-906, (2002)