St. Stephens Quarry, Alabama (SSQ) corehole; an integrated magneto-, bio-, isotopic, and sequence stratigraphic reference section for the icehouse-greenhouse transition

Author(s): Miller, Kenneth; Browning, James; Katz, Miriam; Wright, James; Aubry, Marie-Pierre; Wade, Bridget; Cramer, Benjamin; Kulpecz, Andrew; Rosenthal, Yair
Author Affiliation(s): Primary:
Rutgers University, United States
Rensselaer Polytechnic Institute, United States
University of Oregon, United States
Volume Title: 33rd international geological congress; abstracts
Source: International Geological Congress [International Geological Congress, Abstracts = Congrès Géologique International, Résumés, Vol.33; 33rd international geological congress, Oslo, Norway, Aug. 6-14, 2008. Publisher:], [location varies], International CODEN: IGABBY
Note: In English
Summary: The St. Stephens Quarry, Alabama (SSQ) outcrop and corehole offer a unique opportunity to evaluate the largest global climate cooling event of the Cenozoic (≈33.8-33.5 Ma; latest Eocene-earliest Oligocene) in which warm, high CO2 greenhouse conditions gave way to the icehouse climates that still prevail today. We integrate upper Eocene-lower Oligocene lithostratigraphic, magnetostratigraphic, biostratigraphic, stable isotopic, Mg/Ca, benthic foraminiferal faunal, downhole log, and sequence stratigraphic studies from the SSQ corehole, that provides a superior record to the adjacent outcrop because of limited weathering. The SSQ succession is dissected by hiatuses associated with sequence boundaries: North Twistwood Creek-Cocoa (35.4-35.9 Ma), mid-Pachuta (33.9-35.0 Ma), Shubuta-Bumpnose (lowermost Oligocene; ≈33.6 Ma), Mint Spring-Red Bluff (33.0 Ma), Byram-Glendon (30.5-31.7 Ma), and Bucatunna-Chickasawhay (the famed mid-Oligocene fall; ≈30.2 Ma). Here, we integrate three proxies (ä18O, Mg/Ca, sequence stratigraphy) from SSQ with deep-sea Sites 522 (South Atlantic) and 1218, (Pacific) ä18O and Mg/Ca records to delineate for the first time the three components of the greenhouse-to-icehouse transition (cooling, ice-volume increase, and sea-level fall). A ≈1 0/00 ä18O increase in the SSQ corehole is correlated to the global earliest Oligocene (Oi1) event using magnetobiostratigraphy; this increase is associated with the Shubuta-Bumpnose contact, an erosional surface, and a biofacies shift in the corehole, providing a first-order correlation between ice growth and a sequence boundary that indicates a sea-level fall. A precursor ä18O increase of 0.50/00 (33.8 Ma, mid-Chron C13r) at SSQ correlates with a 0.50/00 increase in the deep Pacific and Atlantic Ocean. Our comparisons reveal that the Eocene-Oligocene transition occurred in two to three steps, with increasing influence by ice volume relative to cooling. In total, ice sheets grew to ≈125% larger than they are today, with an associated ≈105 m relative sea-level (≈67 m eustatic) fall. Our study establishes the relationships among ice volume, ä18O, and sequences: a latest Eocene cooling and minor ice-volume event was followed by an earliest Oligocene ice-volume and cooling event that lowered sea-level and formed a sequence boundary during the early stages of eustatic fall.
Year of Publication: 2008
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Alabama; Alkaline earth metals; Angola Basin; Atlantic Ocean; Biostratigraphy; Boreholes; Calcium; Carbon dioxide; Cenozoic; DSDP Site 522; Deep Sea Drilling Project; East Pacific; Eocene; Equatorial Pacific; Eustasy; Greenhouse effect; IPOD; Ice sheets; Icehouse effect; Isotope ratios; Isotopes; Leg 199; Leg 73; Lower Oligocene; Magnesium; Magnetostratigraphy; Metals; Mg/Ca; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 1218; Ocean Drilling Program; Oligocene; Oxygen; Pacific Ocean; Paleoclimatology; Paleogene; Saint Stephens Quarry; Sea-level changes; Sequence stratigraphy; South Atlantic; Stable isotopes; Tertiary; United States; Upper Eocene
Coordinates: S260651 S260650 W0050646 W0050647
N085300 N085300 W1352200 W1352200
Record ID: 2010071253
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by International Geological Congress Organizational Committee