Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift.
Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift.
复制标题
中国西部Qinling山的多相发掘：沿着岩石圈尺寸的撕裂断层和脉冲的新生代隆起的快速早白垩纪冷却。
DOI：
10.1016/j.tecto.2014.01.011
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发表时间：
2014-03-17
期刊：
影响因子：
2.9
通讯作者：
Dunkl I
中科院分区：
文献类型：
--
作者：
Heberer B;Anzenbacher T;Neubauer F;Genser J;Dong Y;Dunkl I
秦岭-大别造山带西段在晚侏罗世-早白垩世燕山期陆内构造和新生代印度-亚洲碰撞触发的侧向逃逸中起着关键作用。秦岭北方太白花岗岩位于燕山期花岗岩带的最西端。它由多个侵入体组成，并受到新的晚侏罗世和早白垩世锆石U-Pb年龄（156 ± 3 Ma和124 ± 1 Ma）的限制。应用各种年代学（角闪石、黑云母和钾长石的~（40）Ar/~（39）Ar，磷灰石裂变径迹，磷灰石[U-Th-Sm]/He）沿着太白山垂直剖面，对冷却和折返历史进行了细化。新的年龄约束记录了前新生代陆内长期变形以及与印度-亚洲碰撞有关的冷却历史。我们发现太白花岗岩在约1000年左右经历了快速冷却。800至100 °C在早白垩世（约。123至100 Ma），然后是一段时间的缓慢冷却，从约。100米左右。25 Ma，以及新生代低起伏白垩纪冲积平原的脉冲剥露。我们解释了早白垩世的快速冷却和折返是由于活动沿着最近假定的太古代/古元古代华北陆块在阿拉善陆块之下的陆内俯冲的南左岩石圈规模的撕裂断层。晚渐新世至早中新世的冷却阶段可能是由印度-亚洲碰撞和/或太平洋俯冲带期间的横向运动触发的。晚中新世青藏高原隆升导致了强烈的降温作用。本文给出了西秦岭太白花岗岩垂直剖面的年龄数据。U-Pb、Ar-Ar、裂变径迹和U/Th-He定年揭示了一个五步冷却历史。燕山早期的快速冷却发生在沿着岩石圈尺度的撕裂断层。随后的脉冲冷却与青藏高原的生长有关。
The western sector of the Qinling–Dabie orogenic belt plays a key role in both Late Jurassic to Early Cretaceous “Yanshanian” intracontinental tectonics and Cenozoic lateral escape triggered by India–Asia collision. The Taibai granite in the northern Qinling Mountains is located at the westernmost tip of a Yanshanian granite belt. It consists of multiple intrusions, constrained by new Late Jurassic and Early Cretaceous U–Pb zircon ages (156 ± 3 Ma and 124 ± 1 Ma). Applying various geochronometers (40Ar/39Ar on hornblende, biotite and K-feldspar, apatite fission-track, apatite [U–Th–Sm]/He) along a vertical profile of the Taibai Mountain refines the cooling and exhumation history. The new age constraints record the prolonged pre-Cenozoic intracontinental deformation as well as the cooling history mostly related to India–Asia collision. We detected rapid cooling for the Taibai granite from ca. 800 to 100 °C during Early Cretaceous (ca. 123 to 100 Ma) followed by a period of slow cooling from ca. 100 Ma to ca. 25 Ma, and pulsed exhumation of the low-relief Cretaceous peneplain during Cenozoic times. We interpret the Early Cretaceous rapid cooling and exhumation as a result from activity along the southern sinistral lithospheric scale tear fault of the recently postulated intracontinental subduction of the Archean/Palaeoproterozoic North China Block beneath the Alashan Block. A Late Oligocene to Early Miocene cooling phase might be triggered either by the lateral motion during India–Asia collision and/or the Pacific subduction zone. Late Miocene intensified cooling is ascribed to uplift of the Tibetan Plateau. We present age data for a vertical transect of the Taibai granite in the W Qinling. U–Pb, Ar–Ar, fission track and U/Th–He dating revealed a five-step cooling history. Initial rapid Yanshanian cooling occurred along a lithospheric-scale tear fault. Subsequent pulsed cooling is related to the growth of the Tibetan Plateau.