Geology and Hydrogeology of the Caribbean Islands Aquifer System of the Commonwealth of Puerto Rico and the U.S. Virgin Islands
Geology and Hydrogeology of the Caribbean Islands Aquifer System of the Commonwealth of Puerto Rico and the U.S. Virgin Islands
复制标题
波多黎各和美属维尔京群岛加勒比群岛含水层系统的地质和水文地质
DOI：
--
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Rodríguez
中科院分区：
文献类型：
--
作者：
R. Renken;W. Ward;I. Gill;F. Gómez;J. Rodríguez
波多黎各南海岸含水层和北海岸石灰岩含水层系统由第三纪（渐新世至上新世）和第四纪（更新世至全新世）的弱岩化至松散碳酸盐和碎屑沉积岩组成；美属维尔京群岛圣克罗伊岛的 Kingshill 含水层由第三纪晚期（早中新世至上新世）的低岩化至未岩化碳酸盐岩构成。南海岸含水层、北海岸石灰岩含水层系统和 Kingshill 含水层是美国加勒比群岛区域含水层系统分析 (CI-RASA) 研究区面积最广的，也是地下水的主要来源。在波多黎各南海岸地下水省，超过 1,000 米的渐新世至上新世弹性碳酸盐岩石填充了南海岸第三纪盆地。该盆地内的岩相模式似乎受到基准面变化的控制，基准面变化有时受构造运动（隆起和沉降）主导，但也受到陆地运动的影响。长70公里、宽3至8公里的扇三角洲平原覆盖了南海岸地下水省的大部分地区，其沉积主要是由于第四纪冰川引起的海平面和气候变化而发生的。构造运动在第四纪期间发挥的作用要小得多。波多黎各北海岸地下水省的下方是由碳酸盐岩和硅质碎屑岩组成的同斜沿海平原楔形物，这些岩石填充了北海岸第三纪盆地，厚度超过 1,700 米。渐新世晚期的薄基底硅质碎屑层序被渐新世至中新世中期的大部分碳酸盐岩的厚层所覆盖。中新世晚期至上新世时期的球大石石灰岩出露，位于波多黎各西北部的浅层地下区域。渐新世至中中新世岩石初步可划分为5个沉积层序及伴生体系域；这些岩石记录了因相对海平面变化而发生的碳酸盐和少量硅质碎屑沉积。磁宝组是这些层序中最复杂的一个，包含各种碳酸盐岩、碳酸盐-硅质碎屑混合岩和硅质碎屑岩相，反映了差异性隆起、沉降和海侵。美属维尔京群岛圣克罗伊岛 Kingshill 石灰岩的深海沉积相反映了隆起、地堑形成和海水逐渐变浅。上新世的礁石石灰岩床经历了文石骨骼碎片的暴露、重新淹没和流淌淋滤；这些矿床含有片状的白云石透镜体，仅限于结构控制的小型海湾。南海岸含水层是波多黎各南海岸地下水省的主要含水单元，由更新世至全新世大小的聚结扇三角洲形成的巨石至淤泥大小的碎屑组成。
Poorly lithified to unconsolidated carbonate and clastic sedimentary rocks of Tertiary (Oligocene to Pliocene) and Quaternary (Pleistocene to Holocene) age compose the South Coast aquifer and the North Coast limestone aquifer system of Puerto Rico; poorly lithified to unlithified carbonate rocks of late Tertiary (early Miocene to Pliocene) age make up the Kingshill aquifer of St. Croix, U.S. Virgin Islands. The South Coast aquifer, North Coast limestone aquifer system, and Kingshill aquifer are the most areally extensive and function as the major sources of ground water in the U.S. Caribbean Islands Regional Aquifer-System Analysis (CI-RASA) study area. In Puerto Rico's South Coast ground-water province, more than 1,000 meters of elastic and carbonate rocks of Oligocene to Pliocene age infill the South Coast Tertiary Basin. The pattern of lithofacies within this basin appears to have been controlled by changes in base level that were, at times, dominated by tectonic movement (uplift and subsidence), but were also influenced by eustiisy. Deposition of the 70-kilometer long and 3- to 8-kilometer wide fan-delta plain that covers much of the South Coast ground-water province occurred largely in response to glacially-induced changes in sea level and climate during the Quaternary period. Tectonic movement played a much less important role during the Quaternary. The North Coast ground-water province of Puerto Rico is underlain by a homoclinal coastal plain wedge of carbonate and siliciclastic rocks that infill the North Coast Tertiary Basin and thicken to more than 1,700 meters. A thin basal siliciclastic sequence of late Oligocene age is overlain by a thick section of mostly carbonate rocks of Oligocene to middle Miocene age. Globigerinid limestone of late Miocene to Pliocene age crops out and lies in the shallow subsurface areas of northwestern Puerto Rico. Oligocene to middle Miocene age rocks tentatively can be divided into five depositional sequences and associated systems tracts; these rocks record carbonate and minor siliciclastic deposition that occurred in response to changes in relative sea level. The Cibao Formation represents the most complex of these sequences and contains a varied facies of carbonate, mixed carbonate-siliciclastic, and siliciclastic rocks that reflect differential uplift, subsidence, and transgression of the sea. Uplift, graben formation, and gradual shallowing of the sea are reflected within the bathyal-dominated sedimentary facies of the Kingshill Limestone in St. Croix, U.S. Virgin Islands. Reef-tract limestone beds of Pliocene age were subject to exposure, resubmergence, and meteoric leaching of aragonitic skeletal debris; these beds contain patchy lenses of dolomite that are restricted to a small, structurally-controlled embayment. The South Coast aquifer, the principal water-bearing unit of Puerto Rico's South Coast ground-water province, consists of boulder- to silt-size detritus formed by large and small coalescing fan deltas of Pleistocene to Holocene age.