...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Volcanology and Geothermal Research >Morpho-structural evolution of the Cordon Caulle geothermal region, Southern Volcanic Zone, Chile: Insights from gravity and ~(40)Ar/~(39)Ar dating
【24h】

Morpho-structural evolution of the Cordon Caulle geothermal region, Southern Volcanic Zone, Chile: Insights from gravity and ~(40)Ar/~(39)Ar dating

机译：智利南部火山区Cordon Caulle地热区的形态构造演化：重力和〜（40）Ar /〜（39）Ar测年的认识

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

The Cordon Caulle geothermal region (40.5°S) is a 13 km x 6 km, NW-SE elongate, volcano-tectonic depression hosting numerous monogenetic volcanic centers, fhmaroles, and hot-springs, most of which occur spatially associated with the edges of the depression. Volcanism started at approximately 0.3 Ma, with dominantly mafic effusions, and expressed ultimately in postglacial and historic dacite-rhyolite eruptions (1921-1922 and 1960). Three NE-trending gravimetric profiles were carried out across the depression of Cordon Caulle, yielding a residual negative anomaly with the greatest amplitude (-20 mGal) at the center of the depression. A 2D-gravity model given by a 490 m thick shallow body with a density contrast = - 650 kg/m~3, interpreted as a shallow package of dacite-rhyolite lavas and tephra, was found to match the residual anomaly. A dense rock equivalent volume of felsic material on the order of 28 km~3 (25% of the total output of Cordon Caulle) is derived from this thickness. Previous workers explain the origin of felsic rocks at Cordon Caulle in terms of the orientation of the borders of Cordon Caulle relative to the maximum stress direction σ_1 (i.e. NE-trending) prevailing during the Quaternary, according to which NW-trending domains were compressional, favoring stagnation, storage and differentiation of magmas. The dominantly monogenetic style of volcanism, the plateau-like morphology and the negative Bouguer anomaly, on the contrary, are interpreted as an indication of extensional tectonics. Intra-arc extension is proposed to be related to coseismic or postseismic stress relaxation accompanying major thrust events, such as the great 1960 Chilean earthquake, which is consistent, at Cordon Caulle, with the direction of propagation of dikes of the 1960 eruption (i.e. coseismic extension) and present-day subsidence inferred from InSAR data (i.e. postseismic extension). Prior to the Quaternary (8.2-1.6 Ma), nearly east-west compression prevailed at the intra-arc zone. A 5.44 ±0.04 Ma old granodiorite intrusion bracketed by two sub-parallel branches of the regional, margin-parallel Liquine-Ofqui Fault Zone (LOFZ) in a prominent pop-up structure, 15 km to the east of Cordon Caulle, accounts for reverse reactivation of the LOFZ and rapid fault-related exhumation of basement rocks ( > 1 mm/year). We argue that under compression, reverse reactivation of the LOFZ was facilitated by the combined effect of cyclic increase in fluid pressure induced by magmatic-hydrothermal input, and removal of lithostatic load induced by glacial erosion ( > 1.5 mm/year in the vicinity of Cordon Caulle).
机译：Cordon Caulle地热区（40.5°S）是一个13 km x 6 km的NW-SE细长的火山-构造洼地，拥有众多的单相火山中心，火山口和温泉，其中大部分与该地区的边缘在空间上相关抑郁症。火山活动始于约0.3 Ma，主要为铁镁质渗出物，并最终在冰川后和历史上的闪锌矿-流纹岩喷发中表现出来（1921-1922年和1960年）。在Cordon Caulle的凹陷处进行了三个NE趋势的重力剖面，在凹陷中心产生了最大振幅（-20 mGal）的残留负异常。发现了一个由490 m厚的浅体给出的二维重力模型，其密度对比度=-650 kg / m〜3，被解释为是辉绿岩-流纹岩熔岩和特非拉的浅层包裹，与残余异常相匹配。由该厚度得出的长石等效体积为28 km〜3的长英质物质（占Cordon Caulle总产量的25％）。先前的工作人员根据第四纪期间普遍存在的最大应力方向σ_1（即NE趋势）相对于Cordon Caulle边界的方向来解释Cordon Caulle的长英质岩石的起源，据此，NW趋势域是受压的，有利于岩浆的停滞，储存和分化。相反，火山作用占主导地位的单基因形式，高原状形态和负布格异常被解释为伸展构造的指示。弧内扩展被认为与伴随主要推力事件的同震或震后应力松弛有关，例如1960年智利大地震，它在Cordon Caulle与1960年爆发的堤坝的传播方向一致（即同震扩展）和根据InSAR数据推断出的当前沉降（即地震后扩展）。在第四纪之前（8.2-1.6 Ma），弧内带几乎是东西向压缩。在哥顿考勒以东15公里处的一个突出的弹出结构中，由边缘平行的利奎因-奥奎断裂带（LOFZ）的两个亚平行分支包围着一个5.44±0.04 Ma的老花岗闪长岩侵入体，这是反向的LOFZ的重新活化和与基底岩石快速断层相关的掘出（> 1 mm /年）。我们认为，在压缩作用下，岩浆热液输入引起的流体压力周期性增加，以及冰川融蚀引起的岩性静载荷（在Cordon附近> 1.5 mm / year）的去除，共同作用促进了LOFZ的逆向激活。考尔）。

著录项

相似文献

  • 外文文献
  • 中文文献
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