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首页> 外文期刊>Contributions to Mineralogy and Petrology >Evidence of a mantle contribution in the genesis of magmatic rocks from the Neogene Batu Hijau district in the Sunda Arc, South Western Sumbawa, Indonesia
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Evidence of a mantle contribution in the genesis of magmatic rocks from the Neogene Batu Hijau district in the Sunda Arc, South Western Sumbawa, Indonesia

机译：印度尼西亚西南苏巴瓦Sunda弧的新近生巴图希乔地区岩浆岩成因的地幔贡献证据

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Whole-rock geochemical and radiogenic data are combined with in situ trace and isotopic analyses of amphibole grains to characterize the source and the emplacement mechanisms of the magmas of the Sunda arc in the Batu Hijau district, Sumbawa, Indonesia. The low-K calc-alkaline magmatic suite in the area is characterized by a distinctively juvenile signature (143Nd/144Nd ~0.5130). Whole-rock trace element and Pb isotopic data (207Pb/204Pb ~15.603) suggest the involvement of a minimal (<0.1%) sediment component in arc petrogenesis. During the petrogenesis of the calc-alkaline plutons, the involvement of fluids that were not entirely derived from the dehydration of a subducting slab is reflected in the mineral chemistry of the primary hydrous magmatic amphiboles, which contain very low B and Li concentrations. We argue that the B- and Li-poor fluids implicated in the petrogenesis of the calc-alkaline melts were at least partially derived from dehydration of uprising asthenospheric mantle. The δD values of selected hydrous magmatic amphibole grains range between ca. −70‰ and 0‰, consistent with an original mantle-derived signature, which was subsequently modified due to a de-hydrogenation process. We put forward the hypothesis that in the Batu Hijau district an arc-transverse fault system facilitated the rise of asthenosphere-derived melts above a kink, or tear, in the subducting Indian Ocean Plate that underlies the Sunda arc. The melts ascended to upper-crustal levels and underwent fractionation while interacting with the arc crust or metasomatized lithospheric mantle wedge. As a result of this study, we emphasize the significance of crustal-scale faults as conduits that connect the mantle to upper-crustal levels in arc settings. The de-hydrogenation process that the tonalite plutons underwent in the Batu Hijau district may have been crucial to the genesis of associated Cu–Au porphyry mineralization and the development of the Pliocene Batu Hijau deposit. Consequently, we argue that deep structures may facilitate the efficient release of mineralizing fluids at high crustal-levels.
机译：将整个岩石的地球化学和放射源数据与闪石颗粒的原位痕量和同位素分析相结合，以表征印度尼西亚Su巴哇巴图希乔地区Sun他弧的岩浆的来源和沉积机制。该地区的低钾钙碱性岩浆组具有鲜明的少年特征（ 143 Nd / 144 Nd〜0.5130）。整个岩石中的痕量元素和Pb同位素数据（ 207 Pb / 204 Pb〜15.603）表明，弧成岩作用涉及的沉积物成分最少（<0.1％）。在钙碱性p的成岩过程中，并非完全源自俯冲板片脱水的流体的参与反映在初级含水岩浆两性闪石的矿物化学中，其含硼和锂的浓度非常低。我们认为，钙碱性熔体的成岩作用涉及的贫B和贫Li流体至少部分源自起义软流圈地幔的脱水。选定的含水岩浆角闪石晶粒的δD值范围介于大约1到2之间。 −70‰和0‰，与原始的地幔衍生特征一致，随后由于脱氢过程而被修改。我们提出了一个假说，即在黑风H地区，一个弧形断层系统促进了由软流圈衍生的融化物在Sun他弧下方的俯冲印度洋板块的扭结或裂缝上方的上升。熔体上升到上地壳水平并进行分馏，同时与弧壳或交代的岩石圈地幔楔相互作用。这项研究的结果是，我们强调了地壳规模断层作为将地幔连接到弧形环境中上地壳水平的管道的重要性。在巴图Hijau地区，斜方晶石岩体经历的脱氢过程可能对相关的Cu-Au斑岩矿化的成因和上新世巴图Hijau矿床的发育至关重要。因此，我们认为深层结构可能有助于在高地壳水平上有效释放矿化液。

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