GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 43-8
Presentation Time: 3:40 PM


SELKIN, Peter A.1, BERGMANN, Fenna2, BRAINARD, Melissa1, DEKENS, Petra3, GALY, Valier V.4, LANTZSCH, Hendrik2, MANZUETA Jr., Miguel1, MEYNADIER, Laure5, REILLY, Brendan6, RUIZ III, Victor1, SAVIAN, Jairo7, WEBER, Michael8, FRANCE-LANORD, Christian9, SPIESS, Volkhard2, KLAUS, Adam10 and EXPEDITION 354 SCIENCE PARTY, IODP10, (1)Interdisciplinary Arts & Sciences, University of Washington Tacoma, Box 358436, 1900 Commerce Street, Tacoma, WA 98402, (2)MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, 28359, Germany, (3)Department of Geosciences, San Francisco State Univ, 1600 Holloway Ave, San Francisco, CA 94132, (4)Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, (5)Institut de Physique du Globe, Bureau 564 - 1, rue Jussieu, Paris cedex 05, 75238, France, (6)College of Ocean and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, OR 97331-5503, (7)Departamento de Geologia, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Prédio 43126, Porto Allegre, 91501-970, Brazil, (8)Steinmann-Institute, University of Bonn, Poppelsdorfer Schloss, Bonn, 53115, Germany, (9)Crpg, Vandoeuvre les Nancy, 54501, France, (10)International Ocean Discovery Program, Texas A&M University, 1000 Discovery Drive, College Station, TX 77845-9547,

Paleocurrent information is necessary to understand the migration of submarine channels and the architecture of channel-levee systems. Anisotropy of magnetic susceptibility (AMS) provides a means to trace paleocurrent directions in cores lacking other sedimentary indicators of flow direction. Here we present AMS results from oriented core collected from a levee of the active submarine channel near 8° N as part of IODP Expedition 354. Turbidites in the levee were deposited in two intervals, separated by a hemipelagic unit (covering the time period between ca. 15 and 25 cal ka BP). Most turbidites in the levee have well-developed oblate to triaxial AMS fabrics characterized by minimum principal AMS axes offset from vertical due to imbrication of sediment particles. Transport directions derived from AMS imbrication (poles to AMS foliation) are generally to the W in the lower levee section deposit, to the S in the hemipelagic unit, and to the SE in the upper levee. The latter direction is approximately consistent with the modern current direction in the active channel. AMS maxima define a similar pattern, suggesting that AMS in the turbidites is due to current-aligned particles. The general W to E shift in paleocurrent directions during levee construction is consistent with downslope meander migration. However, changes in sediment composition and the broader stratigraphic context provided by seismic and acoustic data suggest that other processes may also be important.