Re–Os isotopes of sulfides in mantle xenoliths from eastern China: Progressive modification of lithospheric mantle
Re–Os isotopes of sulfides in mantle xenoliths from eastern China: Progressive modification of lithospheric mantle
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DOI：
10.1016/j.lithos.2007.06.010
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发表时间：
2008-04
期刊：
影响因子：
3.5
通讯作者：
Xi‐sheng Xu;W. Griffin;S. O’Reilly;N. Pearson;H. Geng;Jianping Zheng
中科院分区：
文献类型：
--
作者：
Xi‐sheng Xu;W. Griffin;S. O’Reilly;N. Pearson;H. Geng;Jianping Zheng
中国东部地幔橄榄岩包体中硫化物颗粒的Re-Os原位同位素数据表明，地壳构造作用与大陆岩石圈地幔流体迁移事件之间存在着密切的时间联系。华夏地块187Re/188Os<；0.11硫化物的TRD和TMA值分为古元古代(∼1.8)、中元古代(∼1.3~1.5)和新元古代(0.9和0.6)四组，与已知的主要地壳生长事件相对应。在中朝地块中，来自硫化物的最可靠的TRD和TMA值以及一些已发表的全岩数据表明，最早的SCLm与最古老的太古宙地壳一起形成，并在古元古代(约1.8Ga)发生修改，对应于地块东西部分的碰撞。中-新元古代年龄(约1.4、0.9、0.6)记录了较年轻的热事件，最新的热事件也是从下地壳捕虏体中的锆石年龄得知的。太古代硫化物和全岩模式年龄的缺乏可能反映了广泛的元古界变质作用，但也可能是由于受主要剪切带控制的软流圈上升带上的火山对年轻的SCLM进行了优先采样。华夏地块广泛存在的中生代岩浆作用可能以富含187Os/188Os超球粒陨石的地幔硫化物和“未来”模式年龄为代表。这可能意味着，亚地球圈地幔在可能最后的1年里已经形成了超球粒体态的Re/Os，这需要它与对流的软流圈隔绝。中国东部之下的南海地幔有着非常复杂的历史，现在是一个不同时代的难熔和可育地幔的混合体，在许多事件中发生了变化。
In situ Re–Os isotopic data for sulfide grains in mantle-derived peridotite xenoliths from eastern China demonstrate a close temporal linkage between crustal tectonism and fluid-migration events in the subcontinental lithospheric mantle (SCLM). In the Cathaysia block, TRDand TMAages of sulfides with187Re/188Os<0.11 cluster in four groups: Paleoproterozoic (∼1.8), Mesoproterozoic (∼1.3 to 1.5 Ga) and Neoproterozoic (0.9 Ga and 0.6 Ga), corresponding to known major crustal growth events. In the Sino-Korean block, the most robust TRDand TMAages from sulfides, and some published whole-rock data, indicate that the earliest SCLM formed together with the oldest Archean crust and was modified in Paleoproterozoic time (ca 1.8 Ga), corresponding to the collision between the eastern and western parts of the block. Meso- to Neoproterozoic ages (ca 1.4 Ga, 0.9 Ga, 0.6 Ga) record younger thermal events, the latest of which also is known from zircon ages in lower-crustal xenoliths. The scarcity of Archean sulfide- and whole-rock model ages may reflect widespread Proterozoic modification of the SCLM, but may also be due to preferential sampling of young SCLM by volcanoes situated along zones of asthenospheric upwelling, controlled by a network of major shear zones. Widespread Mesozoic magmatism in the Cathaysia block may be represented by abundant mantle sulfides with mildly superchondritic187Os/188Os and “future” model ages. This would imply that the sublithospheric mantle has developed a superchondritic Re/Os over perhaps the last 1 Ga, requiring its isolation from the convecting asthenosphere. The SCLM beneath eastern China has had a very complex history, and is now a mixture of refractory and fertile mantle domains with different ages, modified during a number of events.