Probing the roots of the Bushveld Complex: drilling through the lower zones into the intrusive floor

布什维尔德杂岩的镁铁质和超镁铁质部分是地球上最大的层状侵入体，也是最大的铂、铬和钒矿床。在这个项目中，我们申请了德国对布什维尔德综合体下部和主区ICDP钻探作业的贡献，以及对钻探样品的地球化学、实验和微生物工作。这些研究将对布什维尔德杂岩原生岩浆的起源和形成、围岩的上升和同化以及铂、铬和钒的迁移和富集提供重要的新见解。下部岩石和矿物的地球化学特征将产生第一个全面的数据集，包括布什维尔德杂岩中最原始岩石的微量元素浓度和锶、钕、氢、铅的放射性成因同位素比率。根据这些数据，我们将能够确定岩浆的地幔和地壳成分。相辅相成的实验研究有助于了解岩浆结晶和演化的条件，并通过对矿物包裹体的研究确定熔体的成分。该项目的微生物学部分研究了镁铁质和超镁铁质岩石中的深层生物圈，以了解岩石蚀变的过程，例如，地壳流体在低温下的蛇纹岩作用。这项研究得出了关于能量供应的重要结论，以维持地壳中的微生物生态系统。

The mafic and ultramafic part of the Bushveld Complex represents the largest layered intrusion on Earth and the largest deposit of platinum, chromium and vanadium. In this project we apply for the German contribution to the ICDP drilling operation in the Lower and Main Zone of the Bushveld Complex as well as for geochemical, experimental and microbiological work on the drilled samples. These studies will provide important new insights into the origin and formation of the primary magmas of the Bushveld Complex, their ascent and assimilation of wall rocks, and on the transport and enrichment of platinum, chromium, and vanadium. The geochemical characterization of the rocks and minerals of the Lower Zone will yield the first comprehensive data set of trace element concentrations as well as radiogenic isotope ratios of Sr, Nd, Hf, and Pb of the most primitive rocks from the Bushveld Complex. Based on these data we will be able to define the mantle and crustal components of the magmas. The complementary experimental studies allow to understand the conditions of magma crystallization and evolution and define the composition of melts from the study of inclusions in minerals. The microbiological part of the project studies the deep biosphere in the mafic and ultramafic rocks in order to understand the processes of rock alteration like, for example, serpentinization by crustal fluids at low temperatures. This study allows important conclusions about the supply of energy to maintain a microbial ecosystem in the Earth's crust.