Modeling Heat and Mass Transport in the TAG Active Hydrothermal Mound Using a Combined Theoretical/ Observational Approach

摘要 P.I.：Tivey提案编号：97-12153 标题：Modeling heat and mass transfer in the TAG active hydrothermal 丘 使用 一 理论/观测综合法 脊顶热液系统在传递能量和质量通量方面起着重要作用， 从地球内部到表面。1994年秋季，在大洋钻探计划第158航次期间，在大西洋中脊直径200米的TAG活动热液丘上钻了17个孔，以调查流体流动、地球化学通量和活动热液丘的地下性质。 这个土丘可能是最接近塞浦路斯矿体的洋中脊模拟，估计来自黑烟囱的对流热通量为225兆瓦，来自整个土丘地区的对流热通量为500-1000兆瓦。 将进行理论计算，以检查排出土丘的不同流体之间的关系，并检查海水夹带在TAG中的作用，包括夹带的海水量，以及这种夹带留下的印记。 的 沉积物中， 丘 还将进行输运和反应的计算，以便在流体化学与所观察到的矿物学和岩心样品的结构之间建立联系。 重点将放在热液活动最新阶段的模拟过程上，即，与（i）硬石膏（CaSO 4）脉的形成，（ii）与脉状有关的蚀变和矿化，（iii）丘体表面烟囱和硫化物结壳的沉积，以及（iv）目前离开丘体的流体的形成有关。 这些研究将允许量化质量通量 以及对大洋中脊系统沿着已知最大的活动热液土丘之一的矿物沉积、分带和分带细化过程的研究。

Abstract P.I.: Tivey Proposal Number: 97-12153 Institution: WHOI Title: Modeling heat and mass transport in the TAG active hydrothermal mound using a combined theoretical/observational approach Ridge-crest hydrothermal systems play a fundamental role in transferring energy and mass fluxes from the Earth's interior to its surface. In the fall of 1994, 17 holes were drilled in the 200 meter diameter TAG active hydrothermal mound on the Mid-Atlantic Ridge during Leg 158 of the Ocean Drilling Program to investigate the fluid flow, geochemical fluxes, and the subsurface nature of an active hydrothermal mound. This mound is perhaps the closest mid-ocean ridge analog to Cyprus ore bodies and has an estimated convective heat flux from the black smokers of 225 MW, and from the entire mound area of 500-1000 MW. Theoretical calculations will be carried out to examine the relationships among the different fluids exiting the mound, and to examine the role of seawater entrainment at TAG, including the amount of seawater entrained, and what imprint such entrainment leaves in the deposits, and in fluids exiting the mound. Calculations of transport and reaction will also be done, allowing establishment of links between fluid chemistry and observed mineralogy and texture of drillcore samples. The emphasis will be on modeling processes occurring during the most recent phase of hydrothermal activity, i.e., related to (i) formation of anhydrite (CaSO4) veins, (ii) alteration and mineralization associated with veining, (iii) deposition of chimneys and sulfide crusts at the mound surface, and (iv) formation of fluids currently exiting the mound. These studies will allow quantification of mass fluxes and examination of processes involved in mineral deposition, zoning, and zone refinement in one of the largest known active hydrothermal mounds along the mid-ocean ridge sys tem.