Collaborative Research: The Thermal State of 20-25 Ma Lithosphere Subducting at the Costa Rica Margin, Implications for Hydrogeology, Fluxes, and the Seismogenic Zone

费舍尔0001892小麦0002031哈里斯0001944Stein 0001941建议项目是对哥斯达黎加边缘近海俯冲岩石圈的热状态进行多学科调查。热流测量将在两个邮轮上进行，覆盖尼科亚半岛近海的大洋岩石圈部分，这两个部分的组成和构造风格不同，北部形成于东太平洋隆起，南部形成于科科斯-纳斯卡扩张中心，被地形的突然变化隔开。这些测量将伴随着地震和条带准对称研究，以及一个取心计划，该计划将检查与地壳上覆沉积物中流体流动相关的孔隙水化学变化。这些野外计划将伴随着两个数值模拟练习，它们将检查作为岩石圈俯冲的这两个部分的俯冲带的热状态。目标将是确定这些地区俯冲岩石圈的相对热状态、与俯冲板块热状态有关的热和流体通量，以及这些变量如何影响俯冲带过程，包括化学通量速率。

Fisher 0001892Wheat 0002031Harris 0001944Stein 0001941Recommended project is for a multidisciplinary investigation of the thermal state of the subducting lithosphere offshore of the Costa Rica margin. Heat flow measurements will be undertaken in two cruises covering oceanic lithosphere portions offshore of the Nicoya Peninsula that differ in makeup and tectonic style, with the northern portion formed at the East Pacific Rise and the southern portion, separated by an abrupt change in relief, formed at the Cocos-Nazca spreading center. These measurements will be accompanied by seismic and swath bathymmetric study, as well as a coring program that will examine changes in porewater chemistry associated with fluid flow in the sediments overlying the crust. These field programs will be accompanied by two numerical modeling exercises that will examine the thermal state of the subduction zone as these two portions of lithosphere subduct. The goals will be to determine the comparative thermal state of the subducting lithosphere in these regions, the associated heat and fluid fluxes responsible for the subducting slab thermal states, and how these variable affect subduction zone processes, including chemical flux rates.