Geochemistry and petrology of rocks in the Decar area, central British Columbia: Petrologically constrained subdivision of the Cache Creek complex
Geochemistry and petrology of rocks in the Decar area, central British Columbia: Petrologically constrained subdivision of the Cache Creek complex
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不列颠哥伦比亚省中部德卡尔地区岩石的地球化学和岩石学：卡什溪复合体的岩石学约束细分
DOI：
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Ryan Grundy
中科院分区：
文献类型：
--
作者：
D. Milidragovic;Ryan Grundy
不列颠哥伦比亚省中部Decar地区Cache Creek地体的上古生界至下侏罗统变形岩，包括一个由变蛇纹岩或碳酸盐蚀变的超玛菲岩（Trembleur超玛菲岩）组成的中心区域，其东北和西南由绿片岩相连接到角闪岩相火山沉积岩。蚀变最小的超镁铁质岩石以橄榄石-正辉石-尖晶石（黑曜石）矿物学特征和主微量元素地球化学组成特征表明，它们是高度熔融衰竭（F ~0.15 ~ 0.30）岩石圈地幔的残余物。辉石中SiO2含量相对较高，正辉石模态丰度较高，表明其交代作用较晚，可能处于超俯冲环境。根据不可移动和不相容的微量元素丰度，确定了Decar地区4套火山岩和浅侵入岩地球化学套。索契亚演替（上宾夕法尼亚统至下侏罗统）包含高钛碱性和富钛-贫钛拉斑岩套，红岩火成岩杂岩（下二叠统至上三叠统）包含富钛-贫钛套，局部未命名、未变形的麻质侵入物似乎是在Cache Creek杂岩组合后出现的，属于钙碱性套。来自Decar地区样品的地球化学证据表明，Cache Creek复合体的岩石由两个根本不同的构造-地层组合组成。sochea演替的火山岩、侵入岩、灰岩、燧石和泥质岩可能沉积在海洋高原环境中。它们位于一个较低的板块，然后与由Trembleur超镁铁和上覆的红岩火成岩复合体的上地壳岩石组成的上板块并列。
Upper Paleozoic to Lower Jurassic deformed rocks of the Cache Creek terrane in the Decar area, central British Columbia, include a central region of variably serpentinized or carbonate-altered ultramafi c rocks (Trembleur ultramafi te) that is bounded to the northeast and southwest by greenschist faciesto amphibolite facies volcano-sedimentary rocks. The predominant olivine-orthopyroxene-spinel (harzburgitic) mineralogy, and major and trace element geochemical composition of the least-altered ultramafi c rocks suggest that they are remnants of a highly meltdepleted (F ~0.15-0.30) lithospheric mantle. The relatively high SiO2 concentrations and high modal abundance of orthopyroxene in the harzburgite indicate later metasomatism, probably in a supra-subduction setting. Based on immobile and incompatible trace element abundances, we identify four geochemical suites of volcanic and shallow intrusive rocks in the Decar area. The Sowchea succession (Upper Pennsylvanian to Lower Jurassic) contains both the high-Ti alkaline and enriched to depleted tholeiitic suites, the Rubyrock igneous complex (Lower Permian to Upper Triassic) contains the HFSE-depleted suite, and local unnamed, undeformed mafi c intrusions that appear to postdate assembly of the Cache Creek complex are of the calc-alkaline suite. The geochemistry of samples from the Decar area provides evidence that rocks of the Cache Creek complex consist of two fundamentally different tectono-stratigraphic assemblages. Volcanic and intrusive rocks, limestone, chert, and argillite of the Sowchea succession were likely deposited in an oceanic plateau setting. They resided on a lower plate before being juxtaposed against an upper plate consisting of the Trembleur ultramafi te and overlying supracrustal rocks of the Rubyrock igneous complex.
影响因子：
3.5
作者：
J. Warren
通讯作者：
J. Warren