Distinctive composition of copper-ore-forming arc magmas
Distinctive composition of copper-ore-forming arc magmas
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DOI：
10.1080/08120099.2013.865676
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发表时间：
2014-01-02
影响因子：
1.2
通讯作者：
Loucks, R. R.
中科院分区：
文献类型：
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作者：
Loucks, R. R.
生成斑岩和高硫化铜矿床的岩浆肥力一般不是以单个火成杂岩的规模发展，而是以跨越数百公里弧长并包含许多火成杂岩的石化区的规模发展。铜成矿省和时代的范围和持续时间显然是由地球动力学施加的压缩应力，通常持续约5-20马，并促进圈闭幔源玄武岩浆在莫霍面附近的房间，他们冷却非常缓慢，并可能持续足够长的时间来经历间歇性补充分层超镁铁-镁铁堆晶复合物在房间地板上的分离结晶。高压岩浆房中溶解水通过多次补给和结晶作用的积累可以解释成矿钙碱性弧岩浆的化学特征。其特征是Sr、V含量异常高，Sc、Y含量异常低。利用富集元素与亏损元素的比值，可以加强与普通安山质、英安质和流纹质弧岩浆的区别。Sr/Y和V/Sc比值在区分成矿侵入体蚀变程度最小的样品与普通的、不产矿的弧岩浆中是有效的。????????-????????,????????????????,???????????????????????????????,??????????????????????????????????????????????????,????? 5-20Ma，？???????????????????????????????????????????????,?????????????????????????????????????????,??????????????????????????????????????????????????/? ??/?????????????????????????????????????????????
Magmatic fertility to generate porphyry- and high-sulfidation copper ore deposits generally develops, not at the scale of individual igneous complexes, but rather at the scale of petrochemical provinces spanning hundreds of kilometres of arc length, and containing many igneous complexes. The extent and duration of copper metallogenic provinces and epochs are apparently controlled by geodynamically imposed compressive stress that commonly lasts ca 5-20 Ma and fosters entrapment of mantle-derived basaltic magmas in chambers near the Moho where they cool very slowly and are likely to last long enough to experience intermittent replenishment during fractional crystallisation of layered ultramafic-mafic cumulate complexes on the chamber floor. Accumulation of dissolved H2O through multiple cycles of replenishment and crystallisation in high-pressure magma chambers can explain the distinguishing chemical features of copper-ore-forming calc-alkalic arc magmas. The distinguishing features include unusually high contents of Sr and V, and unusually low contents of Sc and Y. The distinction from ordinary andesitic, dacitic and rhyolitic arc magmas can be enhanced by using ratios of enriched elements to depleted elements. The ratios Sr/Y and V/Sc are shown here to be effective in discriminating least-altered samples of ore-forming intrusions from ordinary, metallogenically unproductive arc magmas. ????????-????????,????????????????,???????????????????????????????,??????????????????????????????????????????????????,?????5-20Ma,??????????????????????,???????????????????????- ???????????????????????????????????????????????,?????????????????????????????????????????,??????????????????????????????????????????????????/? ??/?????????????????????????????????????????????