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首页> 外文期刊>Geochemistry, geophysics, geosystems >Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414
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Fluid inclusion petrology and microthermometry of the Cocos Ridge hydrothermal system, IODP Expedition 344 (CRISP 2), Site U1414

机译：IODP Expedition 344（CRISP 2），站点U1414的Cocos Ridge水热系统的流体包裹体岩石学和显微热计量学

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In this study, we present new data from microthermometry of fluid inclusions entrapped in hydrothermal veins along the Cocos Ridge from the IODP Expedition 344 Site U1414. The results of our study concern a primary task of IODP Expedition 344 to evaluate fluid/rock interaction linked with the tectonic evolution of the incoming Cocos Plate from the Early Miocene up to recent times. Aqueous, low saline fluids are concentrated within veins from both the Cocos Ridge basalt and the overlying lithified sediments of Unit III. Mineralization and crosscutting relationships give constraints for different vein generations. Isochores from primary, reequilibrated, and secondary fluid inclusions crossed with litho/hydrostatic pressures indicate an anticlockwise PT evolution during vein precipitation and modification by isobaric heating and subsequent cooling at pressures between similar to 210 and 350 bar. Internal over and underpressures in the inclusions enabled decrepitation and reequilibration of early inclusions but also modification of vein generations in the Cocos Ridge basalt and in the lithified sediments. We propose that lithification of the sediments was accompanied with a first stage of vein development (VU1 and VC1) that resulted from Galapagos hotspot activity in the Middle Miocene. Heat advection, either related to the Cocos-Nazca spreading center or to hotspot activity closer to the Middle America Trench, led to subsequent vein modification (VC2, VU2/3) related to isobaric heating. The latest mineralization (VC3, VU3) within aragonite and calcite veins and some vesicles of the Cocos Ridge basalt occurred during crustal cooling up to recent times. Fluid inclusion analyses and published isotope data show evidence for communication with deeper sourced, high-temperature hydrothermal fluids within the Cocos Plate. The fluid source of the hydrothermal veins reflects aqueous low saline pore water mixed with invaded seawater.
机译：在这项研究中，我们提供了来自IODP Expedition 344 Site U1414沿Cocos Ridge沿Cocos Ridge埋在热液脉中的流体包裹体的显微温度计的新数据。我们的研究结果涉及IODP Expedition 344的一项主要任务，该任务是评估与从中新世早期到最近进入的Cocos板块的构造演化有关的流体/岩石相互作用。低盐含量的含水液体集中在来自Cocos Ridge玄武岩和III单元上覆的岩化沉积物的静脉内。矿化和横切关系为不同的脉代提供了约束。来自初级，再平衡和次级流体包裹体的等渗线与岩石/流体静压力相交，表明在静脉沉淀和等压加热和随后在约210至350 bar之间的压力下冷却的过程中，逆时针PT演化。包裹体内的内部超压和负压使早期包裹体破裂并重新平衡，但也改变了科科斯海岭玄武岩和石化沉积物中的脉代。我们提出沉积物的石化伴随着中新世中期加拉帕戈斯热点活动导致的静脉发育的第一阶段（VU1和VC1）。与Cocos-Nazca传播中心或靠近中美洲海沟的热点活动有关的热对流导致随后的与等压加热有关的静脉改变（VC2，VU2 / 3）。文石和方解石脉内以及科科斯里奇玄武岩的某些囊泡中最新的矿化作用（VC3，VU3）发生在地壳冷却至近代时期。流体包裹体分析和已发表的同位素数据显示了与科科斯板块中更深层的高温高温热流体相通的证据。热液脉的流体源反映了低盐水孔隙水与入侵海水的混合。

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