Orbital- to sub-orbital-scale cyclicity in seismic reflections and sediment character in early to middle Pleistocene mudstone, Santa Barbara, CA

Author(s): Peterson, Carlye D.; Behl, Richard J.; Nicholson, Craig; Lisiecki, Lorraine; Sorlien, Christopher C.
Author Affiliation(s): Primary:
California State University, Long Beach, Geological Sciences, Long Beach, CA, United States
Other:
University of California, Santa Barbara, United States
Volume Title: Geological Society of America, Cordilleran Section, 106th annual meeting; American Association of Petroleum Geologists, Pacific Section, 85th annual meeting; Society of Petroleum Engineers, Western Region, 80th annual meeting
Source: Abstracts with Programs - Geological Society of America, 42(4), p.77; Geological Society of America, Cordilleran Section, 106th annual meeting; American Association of Petroleum Geologists, Pacific Section, 85th annual meeting; Society of Petroleum Engineers, Western Region, 80th annual meeting, Anaheim, CA, May 27-29, 2010. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: High-resolution seismic reflection records and well logs from the Santa Barbara Channel suggest that much of the Pleistocene hemipelagic sedimentary sequence records climate variability on orbital to sub-orbital scales, like strata of the last glacial cycle studied at ODP Site 893. We have developed and tested a new method to extract lithologic cyclicity from high-resolution marine seismic profiles. Seismic reflection data (towed chirp) collected on the R/V Melville 2008 Cruise (MV08) penetrate 10's of meters below seafloor into a ∼1 km-long sequence of south-dipping seismic reflections. Spectral analysis of seismic reflection data and gamma ray logs from stratigraphically similar Pleistocene sections identify similar cyclic character through the section. This correlation suggests that acoustic impedance and physical properties of sediment are linked by climatically-driven oscillations in lithologic composition and fabric during deposition. Furthermore, shifts in spectral character permit identification of basin-wide changes in sedimentation rate or climatic forcing. Where it crops out along the northern shelf of the central Santa Barbara Channel, the early to middle Pleistocene succession (∼1.6-0.7 Ma, middle to upper Pico Formation) is a bathyal hemipelagic mudstone with remarkably rhythmic planar bedding, finely laminated fabric, and well-preserved foraminifera. Unlike the coarser, turbiditic successions in the central Ventura and Los Angeles Basins, this sequence has the potential to record Quaternary global climate change at high resolution. We suggest the following procedure for analysis of this dipping sub-sea succession: 1. Measure reflection amplitude values from several, parallel horizontal transects (constant 2-way-time) of a displayed profile, using absolute values of the SEG-Y data to test the usefulness of the data. Correlate, stack, and spectrally analyze the data series. 2. Sample several horizontal series of the digital SEG-Y data, correlate and stack the series, and analyze for cyclicity. Convert measured distance to true stratigraphic thickness. This method may be used to evaluate the sedimentation rates, age range, and paleoceanographic potential of sedimentary strata before a coring vessel is deployed.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; California; Cenozoic; Clastic rocks; Cyclic processes; East Pacific; Geophysical methods; Geophysical surveys; Glaciation; Leg 146; Lower Pleistocene; Middle Pleistocene; Mudstone; North Pacific; Northeast Pacific; ODP Site 893; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Pleistocene; Quaternary; Reflection methods; Santa Barbara Basin; Santa Barbara California; Santa Barbara County California; Sedimentary rocks; Seismic methods; Southern California; Surveys; United States
Coordinates: N341715 N341715 W1200211 W1200212
N342500 N342500 W1194100 W1194100
Record ID: 2011008824
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