Dynamics of deformation and sedimentation in the northern Sierras Pampeanas : an integrated study of the Neogene Fiambalá basin, NW Argentina ; reply
Dynamics of deformation and sedimentation in the northern Sierras Pampeanas : an integrated study of the Neogene Fiambalá basin, NW Argentina ; reply
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潘皮纳斯山脉北部的变形和沉积动力学：对阿根廷西北部新近纪 Fiambalá 盆地的综合研究；
DOI：
10.1130/b26111.1
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发表时间：
2008
影响因子：
4.9
通讯作者：
J. S. Gomez
中科院分区：
文献类型：
--
作者：
B. Carrapa;J. Hauer;L. Schoenbohm;M. Strecker;A. Schmitt;Arturo Villanueva;J. S. Gomez
阿根廷西部和西北部（27°S–33°S）厚皮的潘皮纳斯山脉形态构造域的特征是逆断层边界的基底块，界定了内部变形的新近纪沉积盆地。安第斯山脉这一部分的前陆盆地演化仍然不是很清楚。例如，厚皮变形如何发展、变形和折返是否存在明显的时空趋势、变形类型如何影响沉积模式、破碎的前陆盆地是否与平板俯冲等区域板块构造过程有关等具有挑战性的问题。潘皮纳斯山脉西北部的菲安巴拉盆地是向普纳高原南缘过渡的几个山间盆地中最大的盆地。该盆地保留了厚厚的大陆新近纪层序，提供了有关厚皮变形和由此产生的沉积动力学的信息。 Fiambala 盆地包含约 4 公里长的河流冲积沉积岩，包括 Tamberia、Guanchin 和 Punaschotter 地层。插入 Fiambala 地层序列中的灰烬的 U-Pb 年代学表明，这些沉积岩的年龄为晚中新世至上新世（8.2 ± 0.3 Ma 至 3.05 ± 0.4 Ma）。沉积学和物源数据表明，Tamberia 组的源头位于现代西部盆地边界范围的西部。关钦地层和普纳肖特地层记录了来自当地来源的输入，包括西部的现代盆地边界范围和北部的南部普纳高原，这表明流域面积在大约 100 年前进行了重组。 5.5马。河流Tamberia 和Guanchin 组记录的粗化向上趋势表明沉积过程中构造和地势增强。 Punaschot-ter 砾岩记录了冲积扇沉积和当地来源。断层运动学数据记录了一种收缩机制，其特征是东西向和东北-西南缩短，在整个中新世中晚期和上新世都很活跃。此外，通过对菲安巴拉盆地与潘皮纳斯山脉（例如贝尔梅霍前陆盆地）和东科迪勒拉山脉的类似沉积盆地进行比较，我们得出结论，该研究区在其早期历史的大部分时间里最初构成了连续且更广泛的前陆盆地系统（薄皮）的组成部分。我们的数据表明，同时代的盆地内变形沿着从贝尔梅霍地区向北到东科迪勒拉山脉的走向。大约同时代的变化。因此，东科迪勒拉山脉、南普纳边缘和潘皮纳斯山脉内其他区域附近地区的 6 Ma 从区域性构造沉积环境转变为更加分区化（厚皮）的构造沉积环境可能反映了与平坦俯冲有关的区域构造过程。我们的数据与现有的沉积学和岩石学证据相结合，表明从陡峭俯冲到平坦俯冲的转变是在~30°S到~26°S之间同步发生的。
The thick-skinned Sierras Pampeanas morphotectonic domain of western and northwestern Argentina (27°S–33°S) is characterized by reverse-fault–bounded basement blocks that delimit internally deformed, Neogene sedimentary basins. Foreland-basin evolution in this part of the Andes is still not very well understood. For example, challenging questions exist as to how thick-skinned deformation develops, if there are distinct spatiotemporal trends in deformation and exhumation, how such deformation styles influence sedimentation patterns, and whether or not broken foreland basins are related to regional plate-tectonic processes, such as flat-slab subduction. The Fiambala basin of the northwestern Sierras Pampeanas is the largest of several intermontane basins in the transition to the southern margin of the Puna Plateau. This basin preserves a thick continental Neogene sequence that provides information on the dynamics of thick-skinned deformation and resulting sedimentation. The Fiambala basin contains ~4 km of fluvial-alluvial sedimentary rocks that comprise the Tamberia, Guanchin, and Punaschotter Formations. U-Pb geochronology of ashes intercalated within the Fiambala stratigraphic sequence demonstrates that these sedimentary rocks are late Miocene to Pliocene (8.2 ± 0.3 Ma to 3.05 ± 0.4 Ma) in age. Sedimentology and provenance data indicate that the source of the Tamberia Formation was located to the west of the modern western basin-bounding range. The Guanchin and Punaschotter Formations record input from local sources, including the modern basin-bounding range to the west and the southern Puna Plateau to the north, suggesting reorganization of the catchment area at ca. 5.5 Ma. The coarsening-upward trends recorded by the fluvial Tamberia and Guanchin Formations indicate enhanced tectonics and relief during sedimentation. The Punaschot-ter conglomerates record alluvial-fan sedimentation and local sources. Fault kinematic data document a contractional regime, characterized by E-W and NE-SW shortening, active throughout the middle-late Miocene and Pliocene. Furthermore, a comparison between the Fiambala basin and similar sedimentary basins in the Sierras Pampeanas (e.g., Bermejo foreland basin) and the Eastern Cordillera leads us to propose that the study area originally constituted an integral part of a continuous and more extensive foreland-basin system (thin-skinned) for much of its early history. Our data suggest coeval intrabasin deformation along strike from the Bermejo region northward to the Eastern Cordillera. The coeval change at ca. 6 Ma from a regional to more compartmentalized (thick-skinned) tectono-sedimentary environment in the regions adjacent to the Eastern Cordillera, the southern Puna margin, and other sectors within the Sierras Pampeanas domain may thus reflect a regional tectonic process related to flat subduction. Our data, combined with existing sedimentological and petrological evidence, imply that the passage from steep to flat subduction occurred synchronously from ~30°S to ~26°S.
影响因子：
4.2
作者：
Deeken, Anke;Sobel, Edward R.;Strecker, Manfred R.
通讯作者：
Strecker, Manfred R.