Uplift and Exhumation of Eclogites and Blueschists in Venezuela: Constraints Based on Structural Analysis, Geothermobarometry, and Geochronology

委内瑞拉榴辉岩和蓝片岩的隆起和折返：基于结构分析、地温气压测量和地质年代学的约束

• 批准号: 9019243
• 负责人: Hans Ave Lallemant
• 金额: --
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 1993-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9019243&HistoricalAwards=false
• 关键词: Uplift; Exhumation; Eclogites; Blueschists; Venezuela

A recently proposed model by the PI explains the uplift and exhumation of high pressure/low temperature rocks in NE Venezuela as the result of oblique subduction beneath an arcuate island arc zone that was convex to the ocean. The normal component of convergence is thought to cause arc-normal contraction structures (folds, thrust faults) and the strike-slip component is thought to cause arc-parallel transcurrent faults and shear zones. An increase in curvature of the arc along strike may increase the strike-slip component of convergence, which in turn causes arc- parallel extension and thickness reduction. The terrane is then uplifted to maintain isostatic equilibrium. On Margarita Island and the Araya Peninsula of NE Venezuela, a Late Cretaceous subduction complex/forearc terrane was extended parallel to the Leeward Antilles volcanic island arc during its uplift and retrograde metamorphism. The model outlined can explain the structural geometry of these uplifted subduction-related rocks, but has not yet been rigorously tested. This project will test the model by collecting data from North Central Venezuela for structural analysis and geothermobarometry. Fission track 40Ar/39Ar, U/Pb, and fluid inclusion studies will be combined with the structural and geothermobarometric data to produce pressure- temperature-time-deformation paths for these rocks. The results of this study will greatly enhance our understanding of Caribbean tectonics, and will give significant insight to the problem of rapid uplift of high pressure/low temperature rocks during collisional tectonic processes.

PI最近提出的一个模型解释了隆起和 委内瑞拉东北部高压/低温岩石的折返 由于弧形岛弧下的斜向俯冲， 向海洋凸出的区域。 的法向分量 辐合被认为是弧法向收缩构造的成因 （褶皱，逆冲断层）和走滑分量被认为是 形成弧形平行的横断层和剪切带。 一个 电弧沿着走向的曲率的增加可以增加 走滑成分的收敛，这反过来又导致弧- 平行延伸和厚度减小。 然后， 上升以维持均衡平衡。 在玛格丽塔岛 和委内瑞拉东北部阿拉亚半岛，晚白垩世 俯冲复合体/前弧带平行于 背风安的列斯群岛火山岛弧在其隆起和 退变质作用 该模型可以解释 这些隆起的俯冲相关岩石的结构几何形状，但 尚未经过严格测试。 该项目将测试 通过收集委内瑞拉中北部的数据， 结构分析和地热压力测量。 裂变径迹 40 Ar/39 Ar， U/Pb和流体包裹体研究将与 构造和地质温压数据来产生压力- 这些岩石的温度-时间-变形路径 结果 这项研究将大大加强我们对加勒比地区的了解， 构造学，并将提供重要的洞察力， 高压/低温岩石快速抬升 碰撞构造作用