T33D-2957
The Evolution of the Surveyor Fan and Channel System, Gulf of Alaska based on Core-Log-Seismic Integration at IODP Site U1417
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Susannah Morey1, Sean P S Gulick1, Maureen A L Walton2, Lindsay Lowe Worthington3, Robert Reece4, John M Jaeger5 and Kittipong Somchat6, (1)University of Texas at Austin, Austin, TX, United States, (2)University of Texas at Austin, Institute for Geophysics, Austin, TX, United States, (3)University of New Mexico Main Campus, Albuquerque, NM, United States, (4)Texas A&M University, College Station, TX, United States, (5)University of Florida, Ft Walton Beach, FL, United States, (6)Texas A & M University College Station, College Station, TX, United States
Abstract:
The transition to quasi-periodic ~100-kyr glacial cycles during the mid-Pleistocene transition (MPT, ~1.2 Ma) saw an acceleration of sediment delivery from the St. Elias orogen. Eroded sediment from the St. Elias Mountains is transferred to the deep sea via glacially carved shelf troughs and eventually to the Aleutian Trench via the Surveyor Channel and Fan system. By analyzing the submarine sediments in this Fan, we can evaluate the source-to-sink relationship between the erosion of an orogen and deep-sea deposition and inform our understanding of the impact of climate on local tectonics. Our work seeks to update depositional models of the unique sedimentary sequences, architecture, and origins of the glacially-fed Surveyor Fan using well-log-seismic correlation and new data from Integrated Ocean Drilling Program (IODP) Expedition 341. Exp. 341 results question proposed ages of major fan stratigraphic packages, necessitating this update. We created an integrated velocity model using discrete core-based p-wave velocities acquired at site U1417 from 100-152m, down-hole sonic log velocities from 152m-476m, and then projected the trend of the sonic log velocity from 476m to the base of the borehole. Previous work has interpreted the Sequence I/II boundary (~300 mbsf at U1417) to correspond with the start of the Surveyor Fan and the onset of tidewater glaciation in the late Miocene and the Sequence II/III boundary (~160 mbsf at U1417) to coincide with the intensification of glaciation and subsequent increase in sediment flux at the MPT. Our updated velocity model places these major sequence boundaries at the correct depths in borehole site U1417. We can use the revised velocity model to correlate lithologic, biostratigraphic, paleomagnetic, and logging data from the borehole/cores to seismic data, allowing for construction of a temporal model for the evolution of the Surveyor fan. We can then examine the relationship between glacial-interglacial cycle duration and intensity with distal sediment flux. Integration with provenance studies can address potential changes in orogen response to deformation and erosion patterns and changes in fan evolution to changing sediment flux.
