Establishing a reference profile for fast-spreading oceanic crust: Petrology and geochemistry of the "Wadi Gideah" cross section in the Oman ophiolite

快速扩张的海洋地壳覆盖了我们地球的大部分地区，被认为是分层和同质的。尽管基于船舶的研究做出了巨大努力，但仍然缺少基于天然样品的完整的现代化学/岩石学剖面。为了通过快速扩张的洋壳建立参考剖面，本研究旨在对阿曼白垩纪蛇绿岩中的地壳剖面进行地球化学/岩石学研究，该剖面被认为是陆地上快速扩张的洋壳岩石圈的最佳范例。为此，在Wadi Tayin Gulf的Wadi Gideah采集了代表约6.5公里快速扩张洋壳的完整剖面（辉长岩、岩脉、玄武岩）。在该项目中，我们专注于（1）岩相学和相分析研究，（2）整体分析表征，（3）量化硫循环和（4）通过使用Sr和O同位素表征热液蚀变随深度的演化。这一剖面在地壳组成的完整性以及所获得的分析数据的质量和一致性方面都是独一无二的。因此，它非常适合于提高我们对地壳增生过程和快速扩张洋壳的初级和次级地球化学循环演化的理解。最后，阿曼参考剖面图为综合大洋钻探计划在1256号站点（赤道太平洋）的钻探提供了科学支持，该站点计划于2011年将目前的钻孔加深到辉长岩地壳。

Fast-spreading oceanic crust covering a large part of our planet is regarded as layered and homogenous. In spite of tremendous efforts by ship-based research, a complete modern chemical/petrological profile based on natural samples is still missing. In order to establish a reference profile through fast-spreading oceanic crust, the present study aims to perform a geochemical/petrological investigation of a crustal section in the Cretaceous ophiolite of Oman, which is regarded as the best example of fast-spreading oceanic lithosphere on land. For this, a complete section (gabbros, dikes, basalts) representative of approximately 6.5 km of fast-spreading oceanic crust was sampled at the Wadi Gideah in the Wadi Tayin massif. Within this project we focus on (1) petrography and phase analytical studies, (2) bulk-analytical characterization, (3) quantifying sulfur cycling and (4) characterizing the evolution of hydrothermal alteration with depth by using Sr and O isotopes. This profile will be unique in terms of completeness of the crustal components and quality and coherence of analytical data to be obtained. Hence, it is well-suited for advancing our understanding of crustal accretion processes and the evolution of primary and secondary geochemical cycles at fast-spreading oceanic crust. Finally, the Oman reference profile provide scientific support for the drilling of the Integrated Ocean Drilling Program (IODP) at Site 1256 (equatorial Pacific) where the deepening of the present hole down into the gabbro crust is scheduled for 2011.