Abstract Phanerozoic growth of continental crust on our planet is one of the important research themes in Earth Science. Here, we present the results of a systematic study of newly found and previously reported Mesozoic igneous rocks, including diorite cumulate, granodiorite cumulate, mafic magmatic enclaves (MME) and host granitoids in the central Lhasa terrane, southern Tibet. These igneous rocks give zircon U Pb crystallization ages of 199–189 Ma. Based on constituent mineral and bulk-rock compositions, the cumulates are best understood as resulting from amphibole, plagioclase and titanite crystallization from a mafic andesitic magma. The host granitoids also show compositional systematics consistent with amphibole-plagioclase fractional crystallization from andesitic magma. The MMEs share many characteristics with their host granitoids in common, including identical crystallization age, similar mineralogy, mineral chemistry and zircon isotopic compositions, representing earlier cumulate derived from the same magmatic system as their host rocks. The magma parental to the studied Early Jurassic igneous rocks is best explained as resulting from partial melting of hydrated ocean crust together with varying continental material. The increasing zircon eHf(t) values of multiple plutons in the central Lhasa terrane with time during ~215–170 Ma indicate its gradual increase in mantle contribution. We present the Early Mesozoic crustal evolution in the Lhasa terrane.

中文翻译：

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藏南中生代地壳演化：拉萨中地体早侏罗世火成岩的制约

摘要 地球大陆地壳显生宙生长是地球科学的重要研究课题之一。在这里，我们展示了对新发现和先前报道的中生代火成岩的系统研究结果，包括闪长岩堆积、花岗闪长岩堆积、基性岩浆飞地 (MME) 和藏南拉萨地体中部的寄主花岗岩。这些火成岩的锆石 U Pb 结晶年龄为 199-189 Ma。根据组成矿物和大块岩石的成分，最好将这些堆积物理解为由角闪石、斜长石和来自镁铁质安山质岩浆的钛石结晶形成的。寄主花岗岩还显示出与安山质岩浆的角闪石-斜长石分馏结晶一致的组成系统。MMEs与其寄主花岗岩具有许多共同特征，包括相同的结晶年龄、相似的矿物学、矿物化学和锆石同位素组成，代表与其寄主岩来自同一岩浆系统的较早堆积物。所研究的早侏罗世火成岩的母岩浆最好解释为水合海洋地壳与不同大陆物质的部分熔化。在~215-170 Ma期间，拉萨地体中部多个岩体的锆石eHf(t)值随时间增加表明其地幔贡献逐渐增加。我们介绍了拉萨地体的早中生代地壳演化。代表来自与其主岩相同的岩浆系统的较早累积。所研究的早侏罗世火成岩的母岩浆最好解释为水合海洋地壳与不同大陆物质的部分熔化。在~215-170 Ma期间，拉萨地体中部多个岩体的锆石eHf(t)值随时间增加表明其地幔贡献逐渐增加。我们介绍了拉萨地体的早中生代地壳演化。代表来自与其主岩相同的岩浆系统的较早累积。所研究的早侏罗世火成岩的母岩浆最好解释为水合海洋地壳与不同大陆物质的部分熔化。在~215-170 Ma期间，拉萨地体中部多个岩体的锆石eHf(t)值随时间增加表明其地幔贡献逐渐增加。我们介绍了拉萨地体的早中生代地壳演化。在~215-170 Ma期间，拉萨地体中部多个岩体的锆石eHf(t)值随时间增加表明其地幔贡献逐渐增加。我们介绍了拉萨地体的早中生代地壳演化。在~215-170 Ma期间，拉萨地体中部多个岩体的锆石eHf(t)值随时间增加表明其地幔贡献逐渐增加。我们介绍了拉萨地体的早中生代地壳演化。