Strata Formation and Preservation on the Eel River Shelf
1998
Borgeld, Jeffry C
The long-term objective of this research is to investigate the processes influencing the emplacement and modification of strata on the continental shelf. This research is a part of the STRATAFORM research program. A primary goal is to identify the modern processes that form strata and to track the modification and ultimate destruction or preservation of such layers into the geologic record. The research objectives of this project are as follows: (1) identify the effects of major flood, storm, and earthquake events on the sedimentology and stratigraphy of the continental shelf by sampling the shelf immediately after events, (2) investigate the relative contributions of post-depositional modifications of these event layers and evaluate the potential of these deposits to be preserved into the geologic record, and (3) use data from the upper few meters of the seabed to examine the along-shelf and across-shelf variability of event layer character and preservation as applied over decadal to thousand-year time scales. The Eel River shelf of northern California is the selected study site. The approach is to sample the shelf immediately after important environmental events and at closely spaced intervals thereafter, using a variety of techniques to monitor the changing character and distribution of event layers. During the past year, cores were collected on two STRATAFORM cruises: on the R/V Point Sur in March 1998 and on the R/V Wecoma in July 1998. Box and piston cores were collected in March; Bothner slow-cores, box cores, and vibracores were collected in July. In addition, side-scan sonar profiles were collected by N. Driscoll (WHOI) in July on the R/V Wecoma and in September on the R/V Coral Sea. Some of the samples collected in March and July have been analyzed. The September data has only been briefly examined thus far.
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