Variations in sediment transport at the central Argentine continental margin during the Cenozoic
Variations in sediment transport at the central Argentine continental margin during the Cenozoic
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DOI：
10.1029/2012gc004266
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发表时间：
2012-10-05
影响因子：
3.5
通讯作者：
Franke, Dieter
中科院分区：
文献类型：
--
作者：
Gruetzner, Jens;Uenzelmann-Neben, Gabriele;Franke, Dieter
被动大陆边缘的沉积盖层构造主要包括重力下坡搬运和顺坡等高岩沉积，受构造、气候和海洋学控制。在阿根廷东部大陆边缘，沉积和侵蚀的历史与南大西洋及其水团的演变密切相关。在这里，我们对位于南纬41度和南纬45度之间的混合沉积体系进行了详细的地震调查。这项研究为先前在阿根廷南部边缘的调查提供了一个向北的补充，这些研究可以作为该地区未来海洋钻探的背景信息。在我们的地震剖面中，突出的特征是海底峡谷、块状废物沉积、等高岩通道和沉积物漂移。区域反射面PLe （65 Ma）以上的4个主要地震单元被明显的区域不整合面分隔开。利用密集的反射地震剖面网格，我们绘制了地震单元的沉积中心几何形状，并推导出了新生代沉积过程的年代表。古新世/始新世（类似于65-34 Ma）以相对缓慢的底水条件下的半深海沉积为特征，而渐新世和中新世早期（类似于34-17 Ma）强烈的南极底水（AABW）环流导致了斜坡上广泛的侵蚀和分离沉积物漂移的生长。在沉积了代表中中新世气候最佳时期（类似于17-14 Ma）的沉积层地震单元后，中新世中晚期（类似于14-6 Ma）重力下坡沉积物输运增加，可能与南美洲构造隆升有关。上新世至全新世单元(
The construction of the sedimentary cover atmost passive continental margins includes gravitational downslope transport and along-slope contourite deposition, which are controlled by tectonics, climate and oceanography. At the eastern continental margin of Argentina the history of deposition and erosion is intimately linked to the evolution of the South Atlantic and its water masses. Here we present a detailed seismic investigation of the mixed depositional system located between 41 degrees S and 45 degrees S. The study provides a northward complement to prior investigations from the southern Argentine margin and together with these may be used as background information for future ocean drilling in the region. Prominent features in our seismic cross sections are submarine canyons, mass wasting deposits, contourite channels, and sediment drifts. Four major seismic units above regional reflector PLe (similar to 65 Ma) are separated by distinct unconformities of regional extent. Using a dense grid of reflection seismic profiles, we mapped the depocenter geometries of the seismic units and derived a chronology of the depositional processes during the Cenozoic. While the Paleocene/Eocene (similar to 65-34 Ma) is characterized by hemipelagic sedimentation under relatively sluggish bottom water conditions, strong Antarctic bottom water (AABW) circulation led to widespread erosion on the slope and growth of a detached sediment drift during the Oligocene and early Miocene (similar to 34-17 Ma). After deposition of an aggradational seismic unit interpreted to represent the Mid-Miocene climatic optimum (similar to 17-14 Ma), gravitational downslope sediment transport increased during the middle to late Miocene (similar to 14-6 Ma) possibly related to tectonic uplift in South America. The Pliocene to Holocene unit (