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首页> 外文期刊>Contributions to Mineralogy and Petrology >Petrogenesis of the granitic Donkerhuk batholith in the Damara Belt of Namibia: protracted, syntectonic, short-range, crustal magma transfer
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Petrogenesis of the granitic Donkerhuk batholith in the Damara Belt of Namibia: protracted, syntectonic, short-range, crustal magma transfer

机译：纳米比亚达巴拉皮带花岗岩Donkerhuk浴盆的纤维化：畸形，透明，短距，地壳岩浆转移

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The areally extensive (> 5000 km(2)), syn-tectonic, ca. 520 Ma, mainly S-type Donkerhuk batholith was constructed through injection of thousands of mainly sheet-like magma pulses over 20-25 Myr. It intruded schists of the Southern Zone accretionary prism in the Damara Belt of Namibia. Each magma pulse had at least partly crystallised prior to the arrival of the following batch. However, much of the batholith may have remained partially molten for long periods, close to the H2O-saturated granite solidus. The batholith shows extreme variation in chemistry, while having limited mineralogical variation, and seems to be the world's most heterogeneous granitic mass. The Nd model ages of similar to 2 Ga suggest that Eburnean rocks of the former magmatic arc, structurally overlain by the accretionary wedge, are the most probable magma sources. Crustal melting was initiated by mantle heat flux, probably introduced by thermal diffusion rather than magma advection. The granitic magmas were transferred from source to sink, with minimal intermediate storage; the whole process having occurred in the middle crust, resulting in feeble crustal differentiation despite the huge volume of silicic magma generated. Source heterogeneity controlled variation in the magmas and neither mixing nor fractionation was prominent. However, due to the transpressional emplacement regime, local filter pressing formed highly silicic liquids, as well as felsic cumulate rocks. The case of the Donkerhuk batholith demonstrates that emplacement-level tectonics can significantly influence compositional evolution of very large syn-tectonic magma bodies.
机译：非常广泛（> 5000公里（2）），Syn-Tectonic，CA。 520 mA，主要是S型Donkerhuk浴盆，通过注射成千上万的片状岩浆脉冲来构建超过20-25 myr。它在纳米比亚的达巴拉腰带中侵入了南部地区的分裂。在以下批次到达之前，每个岩浆脉冲至少部分地结晶。然而，大部分的浴池可能仍然保持部分熔融长时间，接近H 2 O饱和花岗岩固体。浴池显示出化学的极端变化，同时具有有限的矿物学变异，并且似乎是世界上最异质的花岗岩质量。类似于2 Ga的ND模型年龄建议前岩浆弧的伯熊岩石，由逆转楔形结构覆盖，是最可能的岩浆源。地壳熔化由搭式热通量引发，可能是由热扩散引入而不是岩浆平流引入。花岗岩岩浆从源转移到下沉，中间储存最小;尽管产生了大量的硅岩浆，因此在中地壳发生在中地壳中的整个过程。源异质性控制岩浆中的变化，既不是混合也不突出。然而，由于弱压施加方案，局部滤波器压制形成高硅液体，以及肠累积岩石。 Donkerhuk Batholith的情况表明，施加水平构造能够显着影响非常大的Syctonic岩浆体的组成演变。

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