...
  • 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 >Geochemical constraints on the relationship between the Miocene-Pliocene volcanism and tectonics in the Palaoco and Fortunoso volcanic fields, Mendoza Region, Argentina: New insights from ~(40)Ar/~(39)Ar dating, Sr-Nd-Pb isotopes and trace elements
【24h】

Geochemical constraints on the relationship between the Miocene-Pliocene volcanism and tectonics in the Palaoco and Fortunoso volcanic fields, Mendoza Region, Argentina: New insights from ~(40)Ar/~(39)Ar dating, Sr-Nd-Pb isotopes and trace elements

机译：阿根廷门多萨地区Palaoco和Fortunoso火山区中新世-上新世火山与构造之间关系的地球化学约束：〜（40）Ar /〜（39）Ar定年，Sr-Nd-Pb同位素和痕量的新见解元素

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

New ~(40)Ar/~(39)Ar analyses constrain the formation of the volcanic succession of Sierra de Palaoco in the present back-arc of the Andean Southern Volcanic Zone (SVZ), near 36°S, to the Late Miocene and assigns them to the Huincan Ⅱ Formation. The composition of major and trace elements, Sr, Nd and Pb isotopes of the Palaoco and nearby Rio Grande rocks require a strong arc-like component in the mantle that is absent or weak in both Early Miocene (Fortunoso Group) and Pleistocene alkaline lavas (Llancanelo Group) erupted in the same area. We evaluate the relative roles of varying mantle source compositions and crustal contamination in the generation of geochemically very different lavas from the Palaoco, Fortunoso and Rio Grande volcanic fields, north of the Payun Matru Volcano. The source for the Early Miocene Fortunoso(Ⅰ) basalts was a OIB-type mantle devoid of subduction zone input. This type of OIB-like volcanic activity terminated due to a change from an extensional to a compressional tectonic regime. Towards the end of the Miocene renewed alkaline volcanism at Fortunoso (Ⅱ) display a transition to arc-type incompatible element enrichment. Shortly after the calc-alkaline Palaoco volcanism started with a very strong geochemical arc-signature including Ba/La ≈ 60 and La/Nb = 2-3. After a quiesence of 1 Ma the major part of the voluminous Late Palaoco basalts were erupted around 7.5 Ma over a few hundred ka. These are less enriched in Ba and Sr and have compositions like many Holocene rocks of the Southern Volcanic Zone. Isotopically the Fortunoso I and Palaoco rocks are distinct Regional volcanism of the Charilehue, Huincan I and Ⅱ mostly has a moderate arc-type enrichment indicating incipient arc developments. However, Palaoco and La Brea at (c 35°S) show full geochemical arc-signature, and we infer that a frontal arc was established. The subsequent development in the Palaoco-Rio Grande area encompasses renewed late Pliocene calc-alkaline low volume volcanic eruptions (Rio Grande group) succeeded in the Late Pleistocene by alkaline OIB-type eruptions (Uancanelo group). In the light of the course of volcanism to the east, in the Nevado area, where late Miocene-Pliocene calc-alkaline volcanism was followed by Late Pliocene-Pleistocene alkaline volcanism. We propose a scenario where the Nazca plate developed an eastwards widening flat slab from which the east dipping slab before the Late Pliocene translated from Palaoco to Nevado and subsequently retreated passing Rio Grande in the Late Pliocene. Alkaline back-arc volcanism was active east of the arc-volcanism and expanded westwards during the Late Pliocene and Pleistocene.
机译：新的〜（40）Ar /〜（39）Ar分析将塞拉德帕劳科山脉的火山演替的形成限制在安第斯南部火山带（SVZ​​）目前的弧后，接近36°S到中新世晚期和将它们分配给HuincanⅡ组。 Palaoco和附近的Rio Grande岩石的主要元素和微量元素Sr，Nd和Pb同位素的组成要求地幔中有一个强烈的弧状成分，而在中新世早期（Fortunoso组）和更新世碱性熔岩（ Llancanelo集团）在同一地区爆发。我们评估了不同的地幔源组成和地壳污染在来自Payun Matru火山以北的Palaoco，Fortunoso和Rio Grande火山场的地球化学熔岩生成中的相对作用。早中新世Fortunoso（Ⅰ）玄武岩的来源是没有俯冲带输入的OIB型地幔。由于从伸展构造向压缩构造转变，这种OIB类火山活动终止了。在中新世末期，Fortunoso（Ⅱ）发生了新的碱性火山活动，显示了向弧型不相容元素富集的过渡。钙碱性帕劳科火山发生后不久，就开始发生非常强烈的地球化学弧特征，包括Ba / La≈60和La / Nb = 2-3。在静置1 Ma之后，大量的晚期Palaoco玄武岩的大部分在几百ka上喷发了大约7.5 Ma。这些元素中的Ba和Sr含量较低，其成分类似于南部火山区的全新世岩石。同位素上，Fortunoso I和Palaoco岩石是Charilehue独特的区域火山活动，Huincan I和Ⅱ大多具有中等弧型富集，表明初期弧发育。然而，帕劳科和拉布雷亚在（c 35°S）处显示出完整的地球化学弧特征，因此我们推断前弧已建立。 Palaoco-Rio Grande地区的后续发展包括更新的上新世晚期钙钙碱性小体积火山喷发（Rio Grande组），而后更新世晚期则是碱性OIB型喷发（Uancanelo组）。根据东部的火山活动，在内华达州地区，中新世-上新世钙碱性火山作用之后是上新世-更新世碱性火山作用。我们提出了一个方案，即纳斯卡板块向东扩宽，从上新世晚期之前的东倾板从帕劳科转变为内华多，然后在上新世晚期经过里奥格兰德后退。碱性弧后火山活动活跃于弧形火山以东，在上新世和更新世晚期向西扩展。

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