Magma chamber processes in Early Cretaceous Shangzhuang layered mafic intrusion from the North China Craton
Magma chamber processes in Early Cretaceous Shangzhuang layered mafic intrusion from the North China Craton
复制标题
DOI：
10.1002/gj.2856
复制
发表时间：
2017-09
影响因子：
1.8
通讯作者：
Xueming Teng;M. Santosh;T. Tsunogae;Li Tang
中科院分区：
文献类型：
--
作者：
Xueming Teng;M. Santosh;T. Tsunogae;Li Tang
燕山造山带上庄含铁钛矿基性岩体自下而上具有由长长英质岩、长英质辉长岩和辉长岩组成的成分分层特征。侵入杂岩是由富Fe、Ti、Mg的镁铁质水化岩浆分异作用形成的。在这里，我们提出了一个系统的岩石学和矿物数据的各种岩石类型从这个侵入体。斜长石板条表现出富含Na的边缘，具有均匀的核心，并且XAn含量向边缘降低，这是由（Ca + Al）与（Na + Si）的缓慢耦合相互扩散引起的。这些反应还导致在橄榄石周围形成角闪石和斜方辉石环。辉石中的铁-钛氧化物薄片指示亚固相线平衡。原始岩浆的H2O含量估计小于2.5wt.%，岩浆房中的初始结晶温度估计约为884 °C，压力为3.45 kbar。母岩浆的形成是由于地幔上涌、玄武质底侵作用和深部软流圈地幔对流热输入的热化学侵蚀作用，与华北板块下中生代岩石圈大规模减薄密切相关。上庄岩体的最终侵位与陆内拉张背景有关，深度约为14.5 km，表明燕山造山带在晚侏罗世和早白垩世发生了大规模的侵位后隆升和折返。版权所有© 2016约翰威利父子有限公司.
The Fe–Ti ore‐bearing Shangzhuang mafic intrusion in the Yanshan Orogenic Belt, north of the North China Craton, is characterized by compositional layering with troctolite, noritic gabbro and gabbro from the bottom to the top. The intrusive complex formed through fractionation of Fe‐, Ti‐ and Mg‐rich mafic hydrous magma. Here, we present a systematic petrological and mineral data on the various rock types from this intrusion. The plagioclase laths exhibit Na‐enriched rims with homogeneous cores and XAn content decreasing towards the margin, induced by sluggish coupled inter‐diffusion of (Ca + Al) versus (Na + Si). The reactions also resulted in amphibole and orthopyroxene rims surrounding olivine. Subsolidus equilibrium is indicated by Fe–Ti oxide lamellae in pyroxenes. The H2O content of the primary magma is estimated to be less than 2.5 wt.%, and initial crystallization temperature in the magma chamber is estimated as approximately 884 °C at a pressure of 3.45 kbar. The formation of the parent magma was due to the thermal–chemical erosion through mantle upwelling, basaltic underplating and heat input from convection of deep asthenosphere mantle, widely associated with the large‐scale Mesozoic lithospheric thinning beneath the North China Craton. Final emplacement of the Shangzhuang intrusion is related to the intra‐continental extensional setting, at a depth of approximately 14.5 km, suggesting large‐scale, post‐emplacement uplift and exhumation of the Yanshan Orogenic Belt in the Late Jurassic and Early Cretaceous. Copyright © 2016 John Wiley & Sons, Ltd.