A profile of multiple sulfur, oxygen, strontium isotopes and related chalcophile elements through lower slow-spreading crust (IODP Expedition 360, Atlantis Bank, Southwest Indian Ridge)

低速扩张地壳中多种硫、氧、锶同位素和相关亲铜元素的分布图（IODP Expedition 360，亚特兰蒂斯浅滩，西南印度洋中脊）

• 批准号: 319774021
• 负责人: Professor Dr. Jürgen Koepke
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/319774021?language=en
• 关键词: profile; multiple; sulfur; oxygen; strontium

IODP Expedition 360 to Atlantis Bank, at Southwest Indian Ridge (SWIR), ended at 30.01.2016, and is Leg 1 of the SloMo Project, a Multi Phase Drilling Program to drill through the crust/mantle boundary at a slow spreading ocean ridge. The primary objective of the SloMo Project is to test competing hypotheses on the nature of the Moho at the slow spreading oceanic lithosphere. Expedition 360 Hole U1473A was drilled 789.7 m through massive olivine gabbro, gabbro, Fe Ti rich oxide gabbro, gabbronorite, cut by numerous felsic veins. Numerous long intervals of porphyroclastic to ultramylonitic, gabbro, representing a 600 meter thick shear zone, demonstrate that this occurred in a dynamic environment, beginning while the gabbros were partially molten, and continuing as they cooled and were emplaced diapirically and tectonically upward into the zone of diking beneath the rift valley floor. With the help of the Hole U1473U core drilled during Expedition 360, we aim at quantifying the cycling of sulfur and related chalcophile elements in typical slow spreading oceanic crust. The analytical approach will include measuring of multiple sulfur isotopes and trace elements mostly in gabbros and felsic rocks from the drilled core, supported by a few samples from the extrusive crust and from mantle rocks from that area, recovered conventionally by other ship cruises. Downhole concentration profiles of sulfur and chalcophile elements will enable us to identify the main trends of their enrichment and depletion. Multiple sulfur isotopes, in combination with silicate oxygen isotopes and bulk rock Sr isotopes will help to identify whether sulfides observed in various paragenetic mineral assemblages have been formed by primary magmatic or secondary processes, i.e. by seawater derived fluids resulting in water rock interaction. Optical and reflected light microscopy as well as in situ analysis with electron microprobe (EMPA), and laser ablation inductively coupled plasma mass spectrometry (LA ICPMS) will reveal fundamental understanding of the characteristics of related processes involving sulfur mineral formation in the deep slow spreading oceanic crust.

IODP 360 号远征队前往西南印度洋中脊 (SWIR) 的亚特兰蒂斯浅滩，于 2016 年 1 月 30 日结束，是 SloMo 项目的第 1 段，SloMo 项目是一个多阶段钻探计划，旨在钻穿缓慢扩张的洋脊处的地壳/地幔边界。 SloMo 项目的主要目标是测试关于缓慢扩张的海洋岩石圈莫霍面性质的相互竞争的假设。 Expedition 360 Hole U1473A 通过大量长英质脉切割的块状橄榄石辉长岩、辉长岩、富 Fe Ti 氧化辉长岩、辉长岩钻探了 789.7 m。许多长间隔的碎斑岩到超糜棱岩、辉长岩，代表了 600 米厚的剪切带，表明这发生在动态环境中，从辉长岩部分熔融时开始，并在它们冷却并沿底辟和构造向上进入该区域时继续在裂谷底部筑堤。借助 Expedition 360 期间钻探的 U1473U 孔岩心，我们的目标是量化典型缓慢扩张的洋壳中硫和相关亲铜元素的循环。分析方法将包括测量多种硫同位素和微量元素，这些元素主要存在于钻取岩心的辉长岩和长英质岩石中，并得到来自该地区喷出地壳和地幔岩石的一些样品的支持，这些样品通常由其他船舶巡航回收。硫和亲铜元素的井下浓度分布将使我们能够确定它们富集和消耗的主要趋势。多种硫同位素与硅酸盐氧同位素和块岩锶同位素相结合，将有助于确定在各种共生矿物组合中观察到的硫化物是否是由原生岩浆或次生过程形成的，即由海水衍生的流体导致水岩相互作用形成的。光学和反射光显微镜以及电子微探针（EMPA）和激光烧蚀电感耦合等离子体质谱（LA ICPMS）的原位分析将揭示对深部缓慢扩散的海洋中涉及硫矿物形成的相关过程特征的基本了解地壳。