The changing Patagonian landscape: Erosion and westward sediment transfer paths in northern Patagonia during the Middle and Late Pleistocene
The changing Patagonian landscape: Erosion and westward sediment transfer paths in northern Patagonia during the Middle and Late Pleistocene
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不断变化的巴塔哥尼亚地貌：巴塔哥尼亚北部中更新世和晚更新世的侵蚀和向西沉积物转移路径
作者：
T. Villaseñor;D. Tentori;K. Marsaglia;L. Pinto
由于高侵蚀率和沉积物迅速向邻近的海洋盆地转移，更新世冰期促进了重要的景观变化。在巴塔哥尼亚安第斯山脉，巴塔哥尼亚冰盖对景观演变的作用，特别是冰川侵蚀的空间格局及其对沉积物通量的影响，文献记载很少。在此，我们研究了海洋钻探计划（ODP） 861站点在巴塔哥尼亚近海（46°S）的中晚更新世大陆斜坡的沉积记录，以评估冰川作用、山脉侵蚀和大陆边缘地层形成之间的联系。砂粒级（0.063-2 mm）的岩石学分析以及粉粒级（10-63µm）的Nd和87Sr/86Sr测量结果表明，过去35万年的冰川侵蚀主要集中在巴塔哥尼亚基内，钻井地点近端源——丘诺斯变质杂岩的影响较小。这表明侵蚀集中在北巴塔哥尼亚安第斯山脉的核心，与Liquiñe‐Ofqui断裂带和冰川期集中降水带的位置大致吻合，表明气候和构造共同控制了冰川侵蚀。物源信号的时间变化与ODP站点861的地层变化是同步的，这种变化发生在MIS 8 （~240 kyr）冰期之后。在MIS 8之前，大陆斜坡上积累的受限物源信号和粗糙岩相表明空间上受限的侵蚀和沉积物向海洋的有效转移。相比之下，mi8之后非常高的物源变异性和更细的大陆斜坡岩相堆积表明，侵蚀区域的无序扩张和冰沉积物对该地点的更远影响。我们认为，这种变化可能与巴塔哥尼亚冰盖的排水模式的重组以及在最后两个冰期期间出口冰川向大陆边缘的流动有关。
Pleistocene glaciations have promoted important landscape transformations as a result of high rates of erosion and rapid sediment evacuation to adjacent marine basins. In the Patagonian Andes the role of the Patagonian Ice Sheet on landscape evolution, in particular the spatial patterns of glacial erosion and its influence on sediment fluxes, is poorly documented. Here, we investigate the Middle and Late Pleistocene sedimentary record of the continental slope from Ocean Drilling Program (ODP) Site 861, offshore Patagonia (46°S), to evaluate the link between glaciations, mountain range erosion and continental margin strata formation. Petrographic analysis of the sand‐size fraction (0.063–2 mm) and ɛNd and 87Sr/86Sr measurements in the silt‐size fraction (10–63 µm) indicate that glacial erosion over the last 350,000 years has focused within the Patagonian Batholith, with a minor influence of a proximal source to the drilling site, the Chonos Metamorphic Complex. This shows that erosion has focused in the core of the northern Patagonian Andes, coinciding roughly with the location of the Liquiñe‐Ofqui Fault Zone and the zone of concentrated precipitation during glaciations, suggesting a combined climatic and structural control on glacial erosion. Temporal variation in the provenance signal is contemporaneous with a marked change in the stratigraphy of ODP Site 861 that occurred after the glaciation of MIS 8 (~240 kyr ago). Before MIS 8, a restricted provenance signal and coarse lithofacies accumulated on the continental slope indicates spatially restricted erosion and efficient transfer of sediment towards the ocean. In contrast, very high provenance variability and finer continental slope lithofacies accumulation after MIS 8 suggest a disorganized expansion of the areas under erosion and a more distal influence of ice sediment discharge to this site. We argue that this change may have been related to a re‐organization of the drainage patterns of the Patagonian Ice Sheet and flow of outlet glaciers to the continental margin during the last two glaciations.
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巴塔哥尼亚中部区域性中更新世冰川作用
影响因子：
4
作者：
Hein, Andrew S.;Cogez, Antoine;Darvill, Christopher M.;Mendelova, Monika;Kaplan, Michael R.;Herman, Frédéric;Dunai, Tibor J.;Norton, Kevin;Xu, Sheng;Christl, Marcus
通讯作者：
Christl, Marcus
影响因子：
5.3
作者：
B. Yanites;T. Ehlers
通讯作者：
B. Yanites;T. Ehlers
影响因子：
5.3
作者：
Dietrich, R.;Ivins, E. R.;Fritsche, M.
通讯作者：
Fritsche, M.
影响因子：
18.3
作者：
Lamy, Frank;Kilian, Rolf;Steinke, Tatjana
通讯作者：
Steinke, Tatjana
影响因子：
5.3
作者：
Jamieson, Stewart S. R.;Sugden, David E.;Hulton, Nicholas R. J.
通讯作者：
Hulton, Nicholas R. J.