• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The island arc >Petrogenesis of anhydrous clinopyroxenite xenoliths and clinopyroxene megacrysts in alkali basalts from the Ganseong area of South Korea
【24h】

Petrogenesis of anhydrous clinopyroxenite xenoliths and clinopyroxene megacrysts in alkali basalts from the Ganseong area of South Korea

机译：韩国甘城地区碱性玄武岩中无水斜辉石异岩和斜辉石巨晶的成岩作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Late Cenozoic alkali basalts in the Ganseong area of South Korea contain abundant ultramafic xenoliths and clinopyroxene megacrysts. Anhydrous clinopyroxene-rich wehrlite-clinopyroxenites make up the majority of the xenolith population and range from wehrlite through olivine clinopyroxenite to clinopyroxenite. This study investigates the petrogenesis of wehrlite-clinopyroxenite xenoliths and clinopyroxene megacrysts on the basis of petrography and mineral and whole-rock chemistry. Observations such as an absence of carbonate or apatite, high Ti/Eu ratio, and clinopyroxene-dominated mineralogy lead us to rule out peridotite-melt reactions as the origin of the Ganseong wehrlites- olivine clinopyroxenites. The whole-rock compositions (e.g. high abundance of CaO at a given MgO content and low abundance of incompatible elements, such as U, K, P, and Ti compared with mafic melts) indicate that the pyroxenites do not represent crystallized magma itself, but are rather cumulates with a small amount of residual liquid. Anhydrous and orthopyroxene-free mineral assemblages, crystallization sequence of olivine→clinopyroxene→plagioclase, and mineral chemistries (e.g. low Cr# and high TiO _2 abundances in spinels and high TiO _2 and Na _2O abundances in clinopyroxenes at a given Mg#) suggest that relatively anhydrous intraplate alkaline basalt is the most likely candidate for the parent magma. Texture and compositions of the clinopyroxene megacrysts preclude a cognate origin via high-pressure crystallization of the host magma. The clinopyroxene megacrysts occupy the Fe-rich end of the compositional trends defined by wehrlite-pyroxenite clinopyroxenes. Progressive decreases in Mg# and an absence of significant compositional gaps between pyroxenite xenoliths and clinopyroxene megacrysts indicate fractionation and differentiation of a similar parental magma. We suggest that the clinopyroxene megacrysts represent fragments of pegmatitic clinopyroxenites crystallized from more advanced fractionation stages of the evolution of a series of magmatic liquids formed Ganseong wehrlite-clinopyroxenites.
机译：韩国甘城地区晚新生代的碱性玄武岩含有丰富的超镁铁质异质岩和斜辉石巨晶。富含异戊二烯的无水辉石-斜辉石占异种岩的大部分，范围从辉石到橄榄石斜辉石再到斜辉石。本研究在岩相学，矿物学和全岩石化学的基础上，研究了辉绿岩-斜辉石异岩和斜辉石大晶的岩石成因。诸如碳酸盐或磷灰石的缺乏，高的Ti / Eu比值和斜辉石为主的矿物学等观察结果使我们排除了橄榄岩-熔体反应是赣城辉绿岩-橄榄石斜辉石的起源。整个岩石成分（例如，与镁铁质熔体相比，在给定的MgO含量下，CaO含量高，而U，K，P和Ti等不相容元素的含量低）表明，辉石岩本身并不代表岩浆。而是带有少量残留液体的堆积物。无水和不含邻苯二茂铁的矿物组合，橄榄石→斜茂铁茂→斜长石的结晶顺序，以及矿物化学性质（例如，尖晶石中Cr＃和高TiO_2的低丰度以及在给定Mg＃下斜茂铁中的高TiO_2和Na_2O的丰度）表明相对无水的板内碱性玄武岩是母岩浆最有可能的候选人。斜辉石大晶的结构和成分排除了通过宿主岩浆的高压结晶产生的同源起源。斜辉石大晶占据了由辉绿岩-辉石岩斜辉石定义的组成趋势的富铁端。 Mg＃逐渐降低，并且辉石辉石异岩与斜辉石巨晶之间没有明显的组成间隙，表明相似的母体岩浆存在分馏作用和分化作用。我们建议，斜辉石巨晶代表的是从形成甘肃白云母辉绿岩-辉石岩的一系列岩浆液体演化的更高级的分级阶段结晶的斜辉岩斜辉石的碎片。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号