The Role of Fluid Flow in the Cooling of Metamorphic Core Complexes

流体流动在变质核复合体冷却中的作用

• 批准号: 0106953
• 负责人: Christian Teyssier
• 金额: $ 19.95万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106953&HistoricalAwards=false
• 关键词: Role; Fluid; Flow; Cooling; Metamorphic

The role of fluid flow in the cooling history of metamorphic core complexesChristian Teyssier, University of MinnesotaMark Person, Indiana UniversityThe aim of this project is to quantify the effects of fluid flow on the thermal history of metamorphic core complexes during exhumation using a hydrothermal model that incorporates the kinematics of crustal deformation. The numerical model is constrained by field studies based on extensive structural, metamorphic, and thermochronologic data for the Shuswap metamorphic core complex, British Columbia. The modeling allows for quantitative comparison of heat transfer with rock thermochronology and fluid-rock isotopic exchange within the Shuswap system. The modeling helps to test the sensitivity of fluid flow to fault geometry, kinematics, and permeability in the upper crust (horst and graben, domino-style blocks, listric systems), as well as ductile flow and attending heat advection in the lower crust. The modeling also evaluates the effect that fluid flow has on heat distribution and geothermal gradients below the detachment zone, which has implications for the understanding of metamorphic zoning in core complexes. Quantitative results are being compared to the large-scale thermochronology database we developed in the Shuswap metamorphic core complex, British Columbia; this type of generic modeling is directly exportable to other metamorphic core complexes as well as rift zones.The research also sheds light on the systematics of fluid-rock interactions and thermal history in the detachment zones of the Shuswap metamorphic core complex. Towards this end, we are conducting a detailed thermochronologic study based on the fission-track and (U-Th)/He methods on two transects across the Columbia River detachment and fault system that bounds the metamorphic core complex to the east. In the same regions, we are examining fluid-rock interaction by analyzing the stable isotope signature and fluid inclusions within veins, fault rocks, and unfractured rock. This part of the study constrains the nature of the fluids, the extent of fluid pathways, the degree to which surficial fluids penetrate the metamorphic crust, the fluids paleo-temperatures, and possibly also fluid fluxes. We are constructing a suite of numerical experiments to represent isotopic fluid-rock interactions as well as thermochronologic data within this smaller-scale framework in order to better understand fluid flow in detachment/normal fault systems. The detailed field work and geochemical results also serve as ground truth against which the modeling results are tested. The quantitative analysis of fluid flow as a major heat transfer mechanism will help to refine the method in which geologists use cooling rates to determine exhumation rates.

流体流动在变质核心复合物的冷却历史中的作用在印第安纳大学明尼苏达州大学的人，该项目的目的是量化流体流对催水模型期间的变质核心复合物的热历史的影响，该模型结合了构造构层降级的kinematics的水热模型。 数值模型受到基于不列颠哥伦比亚省SHUSWAP变质核心复合物的广泛结构，变质和热量数据的现场研究的约束。 该建模允许在Shuswap系统中与岩石热量和流体岩石同位素交换的传热进行定量比较。 该建模有助于测试上皮（Horst and graben，Domino风格的块，Listric Systems）以及延性流动以及在下层外壳中的热对流的上皮（Horst and and graben，Domino式块，Listric Systems）中流体流动对断层几何形状和渗透性的敏感性。 该建模还评估流体流对脱离区以下热量分布和地热梯度的影响，这对理解核心复合物中的变质分区有影响。 将定量结果与我们在不列颠哥伦比亚省ShusWAP变质核心复合物中开发的大规模热量数据库进行了比较。这种类型的通用建模可直接导出到其他变质核心复合物以及裂谷区域。该研究还阐明了流体岩石相互作用和热历史的系统学在Shuswap Metamorphic Core核心复合物的脱离区中。为此，我们正在对哥伦比亚河脱离和断层系统的两个样带进行基于裂变轨道和（u-th）/HE方法进行详细的热量研究研究，该研究将变质核心复合体界定为东部。 在同一区域，我们正在通过分析静脉，断层岩石和未分离岩石内的稳定同位素特征和流体夹杂物来检查流体岩石相互作用。 该研究的这一部分限制了流体的性质，流体途径的程度，表面流体穿透变质壳的程度，流体的古流体以及可能的流体通量。 我们正在构建一套数值实验套件，以代表该较小规模的框架中的同位素流体岩石相互作用以及热力照相数据，以便更好地了解脱离/正常断层系统中的流体流量。 详细的现场工作和地球化学结果也是对建模结果进行测试的基础真理。流体流作为主要传热机制的定量分析将有助于完善地质学家使用冷却速率来确定挖掘速率的方法。