Drilling 809‐m Hole U1473A in the gabbro batholith at the Atlantis Bank Oceanic Core Complex (OCC) found two felsic vein generations: late magmatic fractionates, rich in deuteric water, hosted by oxide gabbros, and anatectic veins associated with dike intrusion and introduction of seawater‐derived volatiles. Microtextures show a change from compressional to tensional stress during vein formation. Temperatures and oxidation state were obtained from amphibole‐plagioclase and oxide pairs in the adjacent gabbros. Type I veins generally have reverse shear‐sense, with restricted ΔFMQ, high Mt/Ilm ratios, and low‐amphibole Cl/F indicating deuteric fluids. They formed during percolation and fractionation of Fe‐Ti‐rich melts into the primary olivine gabbro. Type II veins are usually hosted by olivine gabbro, occur at dike contacts and the margins of normal‐sense shear zones. They are undeformed or weakly deformed, with highly variable ΔFMQ, low Mt/Ilm ratios, and high‐amphibole Cl/F, indicating seawater‐derived fluids. The detachment fault on which the gabbro massif was emplaced rooted near the base of the dike‐gabbro transition beneath the rift valley. The ingress of seawater volatiles began at >800°C and penetrated at least ~590 m into the lower crust during extensional faulting in the rift valley and adjacent rift mountains. The sequence of the felsic vein formation likely reflects asymmetric diapiric flow, with a reversal of the stress regime, and a transition from juvenile to seawater‐derived volatiles. This, in turn, is consistent with fault capture leading to the large asymmetries in spreading rates during OCC formations and heat flow beneath the rift mountains.

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演化应力场中富含硅的静脉形成，亚特兰蒂斯银行海洋核心复合体

在亚特兰蒂斯银行海洋核心综合体（OCC）的辉长岩基岩上钻809-m孔U1473A，发现了两个长英质脉代：岩浆晚期分馏物，富含氘水，由氧化物辉长岩主生，以及与堤防侵入和引入的钙铝矿脉有关海水衍生的挥发物。微观纹理显示出静脉形成过程中从压应力到拉应力的变化。温度和氧化态从相邻辉长岩中的闪石斜长石和氧化物对获得。I型静脉通常具有反向剪切感觉，ΔFMQ受限制，Mt / Ilm比值高，且双安氏Cl / F值低，表示氘代液体。它们是在富铁钛熔体的渗滤和分馏过程中形成的，形成初级橄榄石辉长岩。II型静脉通常由橄榄石辉长岩托管，发生在堤防接触点和常识剪切带的边缘。它们没有变形或微弱变形，具有高可变的ΔFMQ，低的Mt / Ilm比和高的闪石Cl / F，表明是海水衍生的流体。辉长岩断层所处的脱离断层扎根在裂谷下方的堤坝-gabbro过渡带的底部附近。在裂谷和邻近裂谷的伸展断裂过程中，海水挥发物的侵入始于> 800°C，并至少渗透了约590 m进入下地壳。腓力静脉形成的顺序可能反映了不对称的二尖瓣血流，逆转了应力状态，并从幼体转变为海水衍生的挥发物。反过来，