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印度南部太古宙深层的花岗岩与大陆边缘岛弧系列的年轻花岗岩的地球化学有相似之处。它们显示了有易变的主要为 Eu 异常的但轻稀土富集的图谱。这与典型的太古宙浅层花岗岩的负 Eu 异常成为明显的对照。此处深层的花岗岩相对富集 Ba 和 Sr 而亏损 REE总量和强(电)场的强度元素(HFSE)。桑卡里(Sankari)花岗岩这个深成岩体通常 REE和 HFSF 含量是低的。大部分深成花岗岩看来是代表了具有易变量的圈闭液体的堆积岩及其次要岩相,这是由于花岗质的母源的分馏结晶作用的结果。这种亲缘的花岗质岩浆能够通过在中到下部地壳的太古宙英云闪长岩的分批熔融来产生。桑卡里花岗岩需要一个亏损了 REE 和 HFSE 的英云闪长质的母源。太古宙英云闪长岩和英云闪长质的紫苏花岗岩显示了原始火成岩的地球化学特征组合并且它们的平均成分没有显示一种有意义的 Eu 异常。因此它们不能代表那些正 Eu 异常去补充具有负 Eu 异常的浅层花岗岩。我们的成果推测太古宙深层花岗岩可能代表了这种补充。这种花岗岩类可能形成在中或下部地壳的富水带中并且是通过下部地壳上升的富 CO_2流体相经脱水反应而产生的。
The deep granite in southern Archean India has similarities with the geochemistry of young granites in continental marginal island arc series. They show a spectrum of volatile but mainly light rare earth enrichments that is predominantly Eu. This is in clear contrast to the negative Eu anomaly of a typical Archean shallow granite. Here, the deep granites are relatively enriched in Ba and Sr, while losing the total amount of REE and the intensity element (HFSE) of the strong (electric) field. Sankari granite This deep pluton normally has a low REE and HFSF content. Most of the deep granite appears to represent the sedimentary rocks and their minor lithofacies with a variable amount of trapped liquid as a result of the fractional crystallization of the granitic parent. This kinship of granitic magma can be produced by batch melting of the Archean-type diorites in the middle to lower crust. Sangkali granite requires a source of the Ying-diorite that has depleted REE and HFSE. The Archean English-Chinese diorites and British-dioritic peridosites show a combination of geochemical features of the original igneous rocks and their average composition does not show a meaningful Eu anomaly. Therefore, they can not represent those positive Eu anomalies to supplement shallow granite with negative Eu anomalies. Our results suggest that the deep Archean granite may represent this supplement. Such granitoids may form in the water-rich zone of the middle or lower crust and are produced by dehydration of the CO2-rich fluid phase rising from the lower crust.