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首页> 外文期刊>Geosphere >Birth of the Sierra Nevada magmatic arc: Early Mesozoic plutonism and volcanism in the east-central Sierra Nevada of California
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Birth of the Sierra Nevada magmatic arc: Early Mesozoic plutonism and volcanism in the east-central Sierra Nevada of California

机译：内华达山脉岩浆弧的诞生：加利福尼亚州内华达山脉中东部的早期中生代岩溶作用和火山作用

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摘要

Granitic and volcanic rocks in the east-central Sierra Nevada, western United States, record the earliest stages of magmatism in the eastern Sierra Nevada magmatic arc, allowing us to examine magma sources and connections between plutonic and volcanic processes in the initial stages of arc construction. The Scheelite Intrusive Suite is one of the largest in the Sierra Nevada region, and is composed of the Wheeler Crest Granodiorite, granite of Lee Vining Canyon, and Pine Creek Granite. The Pb/U zircon ages from each unit of the suite suggest assembly between 226 and 218 Ma. The Scheelite Intrusive Suite is a high-K calcic or calc-alkalic suite, compositionally broadly similar to the nearby Late Cretaceous Tuolumne and John Muir Intrusive Suites, though plutons of the Scheelite Intrusive Suite are consistently Ca and Fe rich and lower in Na. Although Triassic granodiorites are isotopically quite similar to nearby Late Cretaceous intrusive suites, the trend toward more isotopically primitive granites is in contrast to the constant or more whole-rock radiogenic Sr trends observed in younger intrusive suites. Along the western margin of the Scheelite Intrusive Suite, the basal Mesozoic volcanic section in the Saddlebag Lake pendant includes silicic volcanic rocks that are in part coeval and potentially comagmatic with Triassic plutonic rocks. Widespread quartz-phyric ash-flow tuffs of Black Mountain, Saddlebag Lake, and Greenstone Lake yield Pb/U zircon ages of 232, 224, and 219 Ma, indicating that felsic ignimbrite volcanism commenced earlier and continued during emplacement of the 226–218 Ma Scheelite Intrusive Suite. Ash-flow tuffs are hydrothermally altered but have high field strength element abundances and Nd isotopic compositions, suggesting affinity to the relatively felsic parts of the Wheeler Crest Granodiorite and the granite of Lee Vining Canyon.
机译：内华达山脉中东部的花岗岩和火山岩， 美国西部，记录了内华达山脉东部岩浆弧中岩浆活动的最早阶段，因此我们可以研究 > 岩浆源以及弧构造初期的火山岩和火山岩 过程之间的联系。 Scheelite 侵入式套房是内华达山脉地区最大的套房之一， 由惠勒·克雷斯特花岗闪长岩， 李维宁峡谷的花岗岩组成和派恩克里克花岗岩。套件中每个单元的Pb / U锆石年龄 建议组装在226和 218 Ma之间。 Scheelite侵入式套件是高K钙或 calc碱性套件，其成分与附近的 晚白垩世Tuolumne和John Muir侵入式套件大致相似，尽管 < Scheelite Intrusive Suite的/ sup的钙元素始终富含Ca 和Fe，而Na含量较低。尽管三叠纪花岗闪长岩 在同位素上与附近的晚白垩世侵入岩 套房非常相似，但向同位素变多的原始花岗岩 发展的趋势却与之相反。在较年轻的侵入式套件中观察到全岩放射源 Sr趋势。沿着Scheelite侵入套件的西部 边缘，Saddlebag Lake悬垂物中的基础中生代 火山岩段包括部分同时代的硅质 火山岩并可能与三叠纪的深成岩形成岩浆 。黑山，马鞍湖和格林斯通湖 的广泛石英石英灰流凝灰岩的Pb / U锆石年龄分别为232、224和219 Ma，表明< sup> 长英质火成岩火山作用开始较早，并在放置226–218 Ma Scheelite侵入性 Suite期间持续 。灰流动凝灰岩是热液改变的，但具有高 场强元素丰度和Nd同位素组成， 建议与Wheeler 的相对稀疏部分具有亲和力。波峰花岗闪长岩和李维宁峡谷的花岗岩。

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  • 来源
    《Geosphere》 |2011年第4期|p.877-897|共21页
  • 作者

    A.P. Barth; J.D. Walker; J.L. Wooden; N.R. Riggs; R.A. Schweickert;

  • 作者单位

    Department of Earth Sciences, Indiana University–Purdue University, Indianapolis, 723 West Michigan Street, SL118, Indianapolis, Indiana 46202, USA;

    Department of Geology, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, Kansas 66045, USA;

    Department of Geological and Environmental Sciences, Stanford University, 450 Serra Mall, Stanford, California 94305, USA;

    School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Campus Box 4099, Flagstaff, Arizona 86011, USA;

    Department of Geological Sciences, University of Nevada, Reno, Nevada 89557, USA;

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