An Important Spreading Event of the Neo‐Tethys Ocean during the Late Jurassic and Early Cretaceous: Evidence from Zircon U‐Pb SHRIMP Dating on Diabase in Nagarzê, Southern Tibet
An Important Spreading Event of the Neo‐Tethys Ocean during the Late Jurassic and Early Cretaceous: Evidence from Zircon U‐Pb SHRIMP Dating on Diabase in Nagarzê, Southern Tibet
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DOI：
10.1111/j.1755-6724.2006.tb00272.x
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
Jiang Sihong;Nie Fengjun;Hu Peng;Liu Yan
中科院分区：
文献类型：
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作者：
Jiang Sihong;Nie Fengjun;Hu Peng;Liu Yan
摘要广泛分布于藏南江孜-赤谷地区的北西向和近东西向辉绿岩(辉长岩)闪长岩墙被认为是新特提斯洋晚期大规模扩张的产物。为了确定这些岩脉的侵位年龄，用SHRIMP法测定了纳加兹辉绿岩中两个样品的锆石年龄。本文获得的206Pb/238U加权平均年龄分别为134.9±1.8 Ma(MSWD=0.65)和135.5±2.1 Ma(MSWD=1.4)。它们不仅代表了辉绿岩的结晶年龄，而且记录了晚侏罗世和早白垩世新特提斯洋的一次重要的扩张事件。这一测年结果对重建青藏高原新特提斯洋晚期的时间格局具有重要意义。
Abstract Widely distributed in Gyangzê‐Chigu area, southern Tibet, NW‐ and nearly E‐W‐trending diabase(gabbro)‐gabbro diorite dykes are regarded as the product of the large‐scale spreading of the late Neo‐Tethys Ocean. In order to constrain the emplacement age of these dykes, zircons of two samples from diabases in Nagarzê were dated by using the U‐Pb SHRIMP method. Two nearly the same weighted mean 206Pb/238U ages were obtained in this paper, which are 134.9±1.8 Ma (MSWD = 0.65) and 135.5 ± 2.1 Ma (MSWD=1.40), respectively. They not only represent the crystallization age of the diabase, but also documented an important spreading event of the Neo‐Tethys Ocean during the late Jurassic and early Cretaceous. This dating result is of great significance to reconstruct the temporal framework of the late Neo‐Tethys Ocean in the Qinghai‐Tibet Plateau.