Faulting and erosion in the Argentine Precordillera during changes in subduction regime: Reconciling bedrock cooling and detrital records
Faulting and erosion in the Argentine Precordillera during changes in subduction regime: Reconciling bedrock cooling and detrital records
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DOI：
10.1016/j.epsl.2015.09.041
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发表时间：
2015-12-15
影响因子：
5.3
通讯作者：
Ortiz, Gustavo
中科院分区：
文献类型：
--
作者：
Fosdick, Julie C.;Carrapa, Barbara;Ortiz, Gustavo
阿根廷前科迪勒拉是一个典型的弧后褶皱和冲断带，记录了与不断变化的俯冲体制有关的构造。利用磷灰石和锆石（U-Th-Sm）/He和磷灰石裂变径迹热年代学方法，研究了前心脏地带和邻近地质区域的折返和断层之间的相互作用。热历史的逆模拟约束东向序列岩石冷却与变形和侵蚀从18至2马在中央前心脏地带跟踪逆冲在这段时间。最年轻的AHe年龄（5-2马）和最高的侵蚀速率位于东部和西部的前心脏地带的末端，并表明，最近的剥蚀集中在其结构边界。此外，同步快速上新世冷却额科迪勒拉，东前Cordillera，和塞拉利昂德尔瓦莱Fertil是coeval与启动基底参与断层在前陆。2000年以来的碎屑锆石U-Pb年代学。16-8.1 Ma Bermejo前陆盆地地层表明，河流连通性向西超出了前科迪勒拉的主科迪勒拉和海岸山脉，随后在约1000年的沉积物来源的重要转变。十马。在这个时候，我们认为，在前科迪勒拉的二叠纪-三叠纪火成岩源的大幅减少，并同时增加回收锆石的古生代地层的签名是最好的解释隆起和侵蚀的前科迪勒拉在扩大的冲断带。基岩热年代学和建模表明，2-6万年之间的滞后时间断层相关的冷却在腹地和变形的碎屑记录在前陆盆地，这表明，构造活跃的半干旱环境，基岩冷却可能是更敏感的断层发生。我们认为，高侵蚀率在额科迪勒拉和东前心血管与增加板间耦合在变浅的俯冲纳斯卡板块，可能会集中应力沿着弱结构边界的前心血管。(C)2015爱思唯尔B. V.保留所有权利。
The Argentine Precordillera is an archetypal retroarc fold-and-thrust belt that records tectonics associated with changing subduction regimes. The interactions between exhumation and faulting in the Precordillera were investigated using apatite and zircon (U-Th-Sm)/He and apatite fission track thermochronometry from the Precordillera and adjacent geologic domains. Inverse modeling of thermal histories constrains eastward in-sequence rock cooling associated with deformation and erosion from 18 to 2 Ma across the Central Precordillera tracking thrusting during this time. The youngest AHe ages (5-2 Ma) and highest erosion rates are located in the eastern and western extremities of the Precordillera and indicate that recent denudation is concentrated at its structural boundaries. Moreover, synchronous rapid Pliocene cooling of the Frontal Cordillera, Eastern Precordillera, and Sierra del Valle Fertil was coeval with initiation of basement-involved faulting in the foreland. Detrital zircon U-Pb geochronology from the ca. 16-8.1 Ma Bermejo foreland basin strata suggests fluvial connectivity westward beyond the Frontal Cordillera to the Main Cordillera and Coast Range followed by an important shift in sediment provenance at ca. 10 Ma. At this time, we suggest that a substantial decrease in Permo-Triassic igneous sources in the Frontal Cordillera and concurrent increase in recycled zircons signatures of Paleozoic strata are best explained by uplift and erosion of the Precordillera during widening of the thrust-belt. Bedrock thermochronology and modeling indicate a 2-6 Myr lag time between faulting-related cooling in the hinterland and the detrital record of deformation in the foreland basin, suggesting that for tectonically active semi-arid settings, bedrock cooling may be more sensitive to onset of faulting. We suggest that high erosion rates in the Frontal Cordillera and Eastern Precordillera are associated with increased interplate coupling during shallowing of the subducting Nazca plate that may concentrate stress along weak structural boundaries of the Precordillera. (C) 2015 Elsevier B.V. All rights reserved.