Flemings, Peter B.; Behrmann, Jan H.; John, Cedric M.; Iturrino, Gerardo J.; Aizawa, Yasutaka; Nguyen Thi Thanh Binh; de Silva, Neil; Dugan, Brandon; Edeskar, Tommy M.; Franke, Christine; Gay, Aurelien; Gilhooly, William Patrick, III; Gutierrez-Pastor, Julia; Jiang Shao-Yong; Li Qianyu; Long, Hui; Moore, J. Casey; Nunoura, Takuro; Pirmez, Carlos; Reichow, Marc; Sawyer, Derek E.; Schneider, Julia; Shumnyk, Anatoliy V.; Suzuki, Takahiro; Takano, Yoshinori; Urgeles, Roger; Yamamoto, Yuzuru; Zampetti, Valentina (2005): Integrated Ocean Drilling Program Expedition 308 preliminary report; Gulf of Mexico hydrogeology; overpressure and fluid flow processes in the deepwater Gulf of Mexico; slope stability, seeps, and shallow-water flow. IODP Management International, College Station, TX, United States, Preliminary Report (Integrated Ocean Drilling Program), 308, 1098 pp., georefid:2008-016936

Integrated Ocean Drilling Program (IODP) Expedition 308 is the first part of a two-component program dedicated to the study of overpressure and fluid flow on the Gulf of Mexico continental slope. We are examining how sedimentation, overpressure, fluid flow, and deformation are coupled in passive margin settings. Expedition 308 tested a multidimensional flow model by examining how physical properties, pressure, temperature, and pore fluid composition vary within low-permeability mudstones that overlie a permeable and overpressured aquifer. We drilled, logged, and made in situ measurements in a reference location where little overpressure was deemed to be present: the Brazos-Trinity Basin. We contrasted these measurements with experiments performed in a region of very rapid Pleistocene sedimentation where overpressure is known to be present: the Ursa region of the northern Gulf of Mexico. Drilling documented severe overpressure in the Ursa region. Postcruise studies will illuminate controls on slope stability, seafloor seeps, and large-scale crustal fluid flow. Two key components of the experimental plan were to take substantial whole-core geotechnical samples for later shore-based analysis and to deploy the temperature and dual pressure probe (developed jointly between the Massachusetts Institute of Technology, Pennsylvania State University, and IODP at Texas A&M University) to measure in situ pressure. Expedition 308 science met many of the objectives proposed in the original IODP Proposal 589-Full3 and provided the foundation to implement long-term in situ monitoring experiments in the aquifer and bounding mudstones in a future expedition designed to meet the full objectives of IODP Proposal 589-Full3. An important achievement of Expedition 308 is to have successfully recorded in situ formation pressure and temperature in an overpressured basin. This is the first time that we know of that such measurements have been obtained.
West: -94.2500 East: -89.0000 North: 28.0600 South: 27.1500
Expedition: 308
Site: 308-U1319
Site: 308-U1320
Site: 308-U1321
Site: 308-U1322
Site: 308-U1323
Site: 308-U1324
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2204/iodp.pr.308.2005 (c.f. for more detailed metadata)
Data download: application/pdf
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