Time scales for vertically moving axial magma chambers at fast-spreading ocean ridges and involved magmatic reactions: Insights from IODP Site 1256

大洋扩张中心的地球动力学模型表明，快速扩张脊下的轴向岩浆房（AMC）是一种瞬态现象，在不同的时间尺度上上下运动，迄今为止还没有很好的量化。由于IODP多次巡航使命“超快速扩展地壳”（1256号站点，赤道东太平洋隆起），现在似乎有可能直接估计这些时间尺度。远征312成功地钻了一个化石导电边界层（CBL）：一个层位的变质，“花岗变晶”岩脉夹在辉长岩和席状岩脉之间，提供了潜在的AMC/岩脉过渡的运动获得基本的时间信息。通过应用现代工具的扩散模拟的“花岗变晶”岩脉层，这是变质的AMC在一个高的位置的热印记内的那些阶段，我们的目标是限制AMC的垂直运动的时间尺度。在AMC向上移动到以前的热液岩脉，预计巨大的反应，造成同化和停止。这是我们试图模拟这些过程的实验，以了解/量化相应的岩浆反应的机制，以评估一个通用的模型，如何污染的MORB下快速扩展的脊进行。

Models on the geodynamics of oceanic spreading centers imply that the axial magma chambers (AMC) under fast-spreading ridges are transient phenomena, moving up and down in distinct time scales which are only poorly quantified up to now. Thanks to IODP multi-cruise mission "Superfast Spreading Crust" (Site 1256, equatorial East Pacific Rise), a direct estimation of these time scales seems now possible. Expedition 312 drilled successfully a fossil conductive boundary layer (CBL): a horizon of metamorphosed, "granoblastic" dikes sandwiched between gabbros and sheeted dikes, providing the potential to obtain fundamental temporal information of the movements of the AMC/Dike transition. By applying modern tools of diffusion modeling to those phases within the "granoblastic" dike horizon, which were metamorphosed by the thermal imprint of the AMC in a high position, we aim to constrain the time scales of vertical movements of AMC's. During upward moving of an AMC into previously hydrothermalized dikes, vast reactions are expected causing assimilation and stoping. It is our attempt to simulate these processes experimentally, in order to understand/quantify the mechanism of the corresponding magmatic reactions for evaluation a general model, how contamination of MORB under fast-spreading ridges proceeds.