Mallarino, Gianni¹, André W. Droxler¹, Laurent Labeyrie², R.T. (Rick) Beaubouef³, Vitor Abreu⁴, Yvon Balut⁵ 
(1) Rice University, Houston, TX 
(2) Laboratoire des Sciences du Climat et de l' Environnement Laboratoire mixte CNRS-CEA, Gif sur Yvette, France 
(3) ExxonMobil Exploration Co, Houston, TX 
(4) ExxonMobil Upstream Research Company, Houston, TX
(5) IFREMER Centre de Brest, Brest, France

ABSTRACT: Nature and Timing of a Mini-Basin Infill During the Last Glacial/Interglacial Sea-Level Cycle (Northwestern Slope of the Gulf of Mexico)

This study integrates multi-beam bathymetry, digital 3.5 kHz profiling, and fourteen giant piston cores collected in Basin IV of the Brazos-Trinity intra-slope system. The main objective of this study is to better constrain the nature and timing of basin filling based upon planktic foraminifer stratigraphy associated with the last glacial/interglacial cycle. 
Four main seismic and lithologic units were recognized, named 4 to 1 from the deepest to the shallowest and corresponding to the Hemipelagics, MTC, DLC, and DC units of Beaubouef and Friedman (2000), respectively. Unit 4, constant in thickness, consists of gray clay with up to 3 cm-thick sand layer intercalations. The sand layers, bundled into two distinct intervals, are estimated to be Marine Isotope Stage (MIS) 5b and 4 in age. Unit 3 is made of a homogeneous blackish clay wedge shaped package, up to 10 m-thick related to slumping at the edge of the basin. Unit 3`s age is younger than MIS 4 and could spans from MIS 3 to the beginning of MIS 2. Unit 2 is comprised of layers of quartz-rich sand up to 11 m-thick separated by grey clay. This unit, the "Upper Fan" of Beaubouef et al. (2003), was deposited during MIS-2. Unit 1 consists of 1-3 m thick layer of grey-brownish clay; it is MIS-1 in age and related to the abandonment of the system. 
It is clear that the sand units were deposited during lowstands of sea-level. The largest volume of sand was delivered during the last glacial maximum.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.