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AGU presentation next week

December 6, 2007

The American Geophysical Union (AGU) Fall Meeting is here in San Francisco next week. This meeting is one of, if not the, biggest congregations of earth, planetary, and space scientists in the world every year. It usually attracts about 15,000 or so.

I love AGU. All the spheres are represented — litho, hydro, strato, tropo, iono, cryo, magneto, and so on. There is plenty of great stuff to see. As these posts from Thermochronic, Yami, and Andrew discuss, AGU typically gets a lot of media attention as well.

I was invited to give a talk about some work I’ve done (and will defend tomorrow) looking at the characteristics and controls of deep-marine sedimentation patterns from a basin offshore of southern California.

The title of the session is:

Mountains to Ocean Deep: Tracking Material Fluxes and Processes During Climatic Change With New and Better Proxies

The first part of the session is focused on fluid transfer and the second part on sediment transfer. The session is on Wednesday and my talk is second-to-last: 11:50am in MW 3001. Check the program when you get there just in case times and/or rooms change. So, come on by before heading out to lunch and check it out.

The title of my talk is:

Controls on Coarse-Grained Sediment Delivery and Distribution in the Holocene Santa Monica Basin, California: Implications for Evaluating Source-to-Sink Flux at Millennial Time Scales in a Deep-Marine Basin

That’s a mouthful. I’ve included the text of the abstract below, or you can find it here.

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Accumulations of terrigenous sediment in deep-marine basins commonly represent the terminal position for source-to-sink sediment flux across a continental margin. The sedimentary succession in the sink records the interactions of external, or allogenic, controls (e.g., eustasy, climatic conditions, tectonic activity) and intrinsic, or autogenic, dynamics (e.g., sediment gravity flow processes and development of depositional relief). Analyzing terrigenous sediment from a sink to determine the relative contributions and thus, the history of external controls has been difficult owing to limited knowledge of event timing. In this study, six new radiocarbon (14C) dates are integrated with five previously published, but recalibrated, dates from a 12.5 meter-thick turbidite section from ODP Site 1015 in Santa Monica Basin, offshore southern California (33°42.925″N; 118°49.185″W; water depth = 900 m). This borehole is tied to high-resolution seismic-reflection profiles that cover a 1,000 km2 area of the middle and lower Hueneme submarine fan and most of the basin plain. This regional stratigraphic framework provides the highest temporal resolution to date for a thick-bedded Holocene turbidite succession, permitting an evaluation of source-to-sink controls at millennial (103 yr) scales. The depositional history from 7 ka to present indicates that the recurrence interval for large turbidity current events is relatively constant (300-360 yrs), but the volume of sediment deposited on the fan and in the basin plain has increased by a factor of two during this period. Moreover, the amount of sand per event (i.e., thickness of turbidite bed) on the basin plain during the same interval increased by a factor of six. Maps of sediment distribution derived from correlation of seismic-reflection profiles indicate that this trend cannot be attributed exclusively to autogenic processes (e.g., lobe progradation). The observed variability in sediment accumulation rates is thus mainly controlled by allogenic factors, including: (1) increased discharge of Santa Clara River as a result of increased magnitude and frequency of ENSO events from approximately 2 ka to present; (2) decreasing rates of sea-level rise (i.e., sea level reaches present stand approximately 7 ka); and (3) an apparent change in routing of coarse-grained sediment within the staging area at approximately 2-3 ka (i.e., from direct river input to indirect, littoral cell input into Hueneme submarine canyon). The Holocene history of the Santa Clara River-Santa Monica Basin source-to-sink system demonstrates how the interaction of varying sediment flux and changes in dispersal pathways affects the basinal stratigraphic record.

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Hope to see you there! A group of geology bloggers, including me, are also planning to meet up and interact with each other in the real-life world. Pay attention to this post over at Green Gabbro, or keep your eyes peeled for another post with more details about this meet-up.

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