A paleoclimatic reconstruction of the Carboniferous-Permian paleovalley fill in the eastern Paganzo Basin: Insights into glacial extent and deglaciation of southwestern Gondwana
A paleoclimatic reconstruction of the Carboniferous-Permian paleovalley fill in the eastern Paganzo Basin: Insights into glacial extent and deglaciation of southwestern Gondwana
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帕甘佐盆地东部石炭纪-二叠纪古谷充填物的古气候重建：对冈瓦纳西南部冰川范围和消融的见解
DOI：
10.1016/j.jsames.2019.102236
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发表时间：
2019
影响因子：
1.8
通讯作者：
Schencman, L. Jazmin
中科院分区：
文献类型：
--
作者：
Pauls, Kathryn N.;Isbell, John L.;McHenry, Lindsay;Limarino, C. Oscar;Moxness, Levi D.;Schencman, L. Jazmin
在石炭纪中期，冰中心位于今天的阿根廷西部消失，直到晚新生代与安第斯山脉的冰川作用。中石炭纪冰川的消失和随后的气候变化，记录在帕甘佐盆地，已被归因于全球事件和驱动因素，如大气中二氧化碳浓度的增加和冈瓦纳大陆在南极的位置转移。然而，在南美洲东部，冰川仍然保持着相同的古纬度，直到晚二叠世才从冈瓦纳消失。本研究调查的链接，当地的驱动程序，与其他全球驱动程序相结合，以解释早期的冰川消退沿着冈瓦纳西部边缘。为此，对阿根廷西部帕甘佐盆地东部的几个露头进行了取样，以进行蚀变化学指数（CIA）地球化学分析。在这里，我们测试的适用性CIA作为一个古气候代理层在奥尔塔-马兰桑古河谷，历史上被认为是冰川。作者最近的一项研究表明，古河谷不是冰川作用的，而是由于河流作用的延伸和挖掘而形成的。然而，该古河谷系统的晚古生代地层与Paganzo盆地的其他部分相似。从古河谷样品的结果表明，这一地区是间歇性的潮湿和干旱的时间，但与整体干旱的配置文件。这一特征主要是由于古河谷的性质，频繁的罗克瀑布、冲积扇/扇三角洲和湖相沉积物重力流（马兰桑组）迅速掩埋了古河谷，防止了任何明显的化学风化虽然整个宾夕法尼亚气候特征似乎相对干旱（马兰桑，洛马Larga和索尔卡Fms。），看来，晚宾夕法尼亚和二叠纪拉科利纳组沉积期间的气候比以前认为的更潮湿。
During the mid-Carboniferous, ice centers located in present-day western Argentina disappeared until the late Cenozoic with glaciation of the Andes. The disappearance of mid-Carboniferous glaciers and the subsequent climate shift, recorded in the Paganzo Basin, has been attributed to global events and drivers, such as increased atmospheric CO2concentrations and the shifting position of Gondwana across the South Pole. However, glaciers continued at the same paleolatitude in eastern South America and did not disappear from Gondwana until the Late Permian. This study investigates links to local drivers that acted in combination with other global drivers to explain the early deglaciation along the western margin of Gondwana. To do this, several outcrops within the eastern portion of the Paganzo Basin in western Argentina were sampled for the Chemical Index of Alteration (CIA) geochemical analyses. Here, we test the applicability of the CIA as a paleoclimate proxy on strata in the Olta-Malanzán paleovalley that historically was thought to have been glaciated. A recent study by the authors has shown that the paleovalley was not glaciated, but owes its origin to extension and excavation by fluvial processes. However, the late Paleozoic stratigraphy of this paleovalley system is similar to the rest of the Paganzo Basin. The results from the paleovalley samples show that this area was intermittently humid and arid through time, but with an overall arid profile. This signature is predominantly due to the nature of the paleovalley, which was subjected to rapid burial from frequent rock falls, progradation alluvial fans/fan deltas, and lacustrine sediment gravity flows (Malanzán Fm.), which prevented any significant chemical weathering. While the overall Pennsylvanian climatic signature appears to be relatively arid (Malanzán, Loma Larga, and Solca Fms.), it seems that the climate during the deposition of the late Pennsylvanian and Permian La Colina Formation was more humid than previously thought.
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阿根廷帕甘佐盆地石炭纪-二叠纪帕基亚地层的古地磁：对晚古生代南美洲和冈瓦纳大陆明显的极地漂移路径的影响
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