High-frequency time-series of the dynamic sedimentation processes on the western shelf of the Mississippi River Delta |
| |
| Institution: | 1. Dpto. Estratigrafía, Facultad de Ciencias Geológicas, UCM, IGEO-CSIC, C/Jose Antonio Novais 12, 28040 Madrid, Spain;2. Dpto. Petrología y Geoquímica, Facultad de Ciencias Geológicas, UCM, IGEO-CSIC, C/Jose Antonio Novais 12, 28040 Madrid, Spain;3. Dpto. Ciencias de la Tierra, Universidad de Cádiz, Polígono Río San Pedro s/n., 11510 Puerto Real, Cádiz, Spain;4. Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain;1. School of Marine Science, SunYat-sen University, Guangzhou 510275, China;2. Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Guangzhou 510275, China;3. Guangdong Provincial Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, China;4. Virginia Institute of Marine Science, 1208 Greate Road, Gloucester Point, VA 23062, USA |
| |
| Abstract: | Multiple box cores were collected on the continental shelf in the Mississippi Deltaic Region adjacent to Southwest Pass and analyzed for particle reactive radionuclides 234Th and 7Be to examine seasonal sediment dynamics associated with variations of river discharge and hydrodynamics. Three stations located along a line west of Southwest Pass were cored and reoccupied in October, November, and December of 2003 and March, April, and May of 2004. High-frequency sampling (∼monthly) comparable to the short half-life of the radiotracers (234Th t1/2=24.1 d; 7Be t1/2=53.3) enabled us to isolate the relative influence that various forcing agents (river discharge, waves, currents) had on sediment inventories of 7Be and 234Th. In addition, the primary source of 7Be (fluvial) differs from 234Th (marine), providing further insight into processes affecting sediment transport and supply. Monthly 7Be inventories showed a significant positive relationship to river discharge (P=0.03) proximal to Southwest Pass. Sites further from Southwest Pass exhibited little to no relationship between 7Be inventories and river flow. At these sites, monthly 7Be inventories demonstrated a significant positive relationship with average wave orbital velocity (P<0.01). During our sampling period, the transport of 7Be-rich sediments to sites located on the middle to outer shelf were dependent on sea conditions not river discharge. Relatively high wave orbital velocities potentially allow particles to remain in suspension longer and travel further distances before initial deposition. In addition, 234Th inventories showed evidence of sediment focusing during periods of high wave orbital velocities. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
