Collaborative Research: Climatic and Tectonic Controls on Sedimentation and Incision in the Marginal Basins of the Southern Puna Plateau

在上新世晚期和第四纪，世界各地都观察到碎屑物质的积累速率和粗化的增加，并被用来推断侵蚀速率的增加。这一全球信号归因于气候变化，特别是海平面下降、冰川扩张和气候振荡加剧。然而，在许多情况下，由于旧物质的再沉积和压实，以及缺乏经过充分研究的、年代久远的遗址，这种侵蚀速率的增加可能被夸大了。局部构造变形和构造抬升可以充分解释真正观察到的上新世-第四纪沉积速率增加的情况。阿根廷西北部普纳高原的边缘盆地是一个理想的天然实验室，可以将碎屑、结构和地貌记录中所含的信息转化为对构造和气候相对作用的理解。该项目旨在通过测定上新世砾岩沉积时间、确定砾岩的来源、限制源区的剥露和侵蚀历史以及调查盆地的近期构造和地貌历史来检验气候与构造假说。将利用现有的气候和构造数据对源侵蚀、沉积和随后的盆地切割进行相关分析，以评估普纳高原沿着的气候和/或构造与沉积和切割之间是否存在遗传联系。气候与构造对侵蚀和沉积的影响是一个持续的争论。有人提出，全球气候变化在过去360万年前（上新世时间）引发了全球侵蚀和沉积速率的明显增加。本研究的目标是通过区分和限制负责沉积上新世砾岩沿着普纳高原，阿根廷西北部的边缘不同的过程，有助于这一辩论。该高原是南美洲普纳高原的一部分，是地球上第二大高原。这一项目将产生新的成果，不仅能够为气候与构造的辩论提供信息，而且还将阐明构造和地表过程对一般沿着大陆高原沉积岩记录的产生和保存的影响。

An increase in accumulation rates and a coarsening of clastic material has been observed all around the world in Late Pliocene and Quaternary time, and has been used to infer an increase in erosion rates. This global signal has been attributed to climate change, particularly to lowered sea-level, glacial expansion and increased climatic oscillation. However, in many cases this increase in erosion rate may be overstated due to re-deposition and compaction of older material, and a lack of well-studied, well-dated sites. Local structural deformation and tectonic uplift may adequately explain cases in which in increase in sedimentation rates in Plio-Quaternary time is truly observed. The marginal basins of the Puna Plateau in northwestern Argentina are an ideal natural laboratory in which to translate the information contained in the detrital, structural and geomorphic records into an understanding of the relative roles of tectonics and climate. This project aims to test the climate versus tectonics hypothesis by dating the timing of deposition of the Pliocene conglomerates, determining the provenance of the conglomerates, constraining the source region(s) exhumation and erosion history, and investigating the recent tectonic and geomorphological history of the basins. Correlations between source erosion, sedimentation and subsequent basin incision will be made with existing climatic and tectonic data to assess whether or not a genetic link exists between climate and/or tectonics and sedimentation and incision along the Puna Plateau. The effect of climate versus tectonics on erosion and sedimentation is an ongoing debate. It has been proposed that global climate change triggered an apparent worldwide increase in erosion and sedimentation rates in the last 3.6 million years ago (Pliocene time). The goal of this study is to contribute to this debate by discriminating and constraining different processes responsible for the deposition of Pliocene conglomerates along the margin of the Puna Plateau, northwestern in Argentina. The plateau is part of the Puna-Altiplano plateau in South America, the second largest plateau on Earth. This project will lead to new results that will be able not only to inform the climate versus tectonics debate but will also elucidate the effects of tectonic and surface processes in the creation and preservation of the sedimentary rock record along continental plateaus in general.