Collaborative Research: Tectonic and climatic forcing of hydrological systems in the southern Great Basin: Implications for ancient and future aquatic system resilience

南部的大盆地是北美最干旱的地区之一。这里几乎没有常年溪流，但却有1000条泉水。这些泉水是水生生物的岛屿，是沙漠的海洋。值得注意的是，这些孤立的泉水中包含着各种各样的水生生态系统，甚至还有特有的鱼类、春螺和其他水生生物。许多只能在水中生存的水生物种的存在证明了这些泉水是一个多年生排水系统的遗迹，而一些特有物种的存在需要在百万年的时间间隔内进行遗传分化，这表明至少有一些泉水在地质时间尺度上从未干涸过。因此，水生生物地理模式为该地区的地质和水文历史提供了信息。这是一个扩大已经很大的区域生物地理数据库的项目，并使用新的和先前存在的数据组合来测试大盆地南部构造和古水文演化的模型。pi将集中在两个时间尺度上：晚中新世到现在的区域伸展分裂和冰期/间冰期气候旋回。在板块边界动力学的推动下，该地区的伸展史始于研究区东部约14 Ma，并向西迁移至内华达山脉前缘。他们将使用区域准三维运动/构造-地貌-水文耦合模型来模拟这一演变，该模型将沿断层、质量分布、岩浆作用、均衡补偿和弯曲变形与水文和地表地貌过程（包括侵蚀和沉积）完全耦合。水文系统的扩展破碎化将被研究，地下水流动将成为区域构造-地貌-水文模型的一个组成部分，地下水流动是模拟泉水形成的必要条件。模拟的古水文历史将根据生物数据（水生生物群清单、微生物和大型动物DNA以及遗传分化时间）与岛屿生物地理学理论进行检验。pi将测试水文破碎年代学与特有物种的关系，以及根据地下水年龄和气候驱动模型推断的生态系统多样性与春季恢复力的关系。他们将利用这些结果来评估和改进他们的构造/古水文模型。

The southern Great Basin is among the most arid regions in North America. It has almost noperennial streams, but does have 1,000 springs. These springs are islands of aquatic habitatin an ocean of desert. Remarkably, many of these isolated springs contain diverse aquaticecosystems and even endemic species of fish, spring snails, and other aquatic organisms. Thepresence of many aquatic species that can only survive in water is evidence that the springsare remnants of a perennial drainage system, and the presence of endemic species requiringintervals in the million-year range for genetic divergence are evidence that at least someof these springs have never desiccated over the geological time scale. Aquatic biogeographicalpatterns thus inform the geological and hydrological history of the region.This is a project to expand the already-large regional biogeographical database and to use the combinednew and preexisting data to test models of tectonic and paleohydrological evolution of thesouthern Great Basin. The PIs will focus on two timescales: that of the extensional breakup ofthe region from the late Miocene to the present and that of glacial/interglacial climate cycles.Extensive work has been done to understand the extensional history of the region, which startedin the eastern portion of the study area at ~14 Ma and migrated westward to the Sierra Nevadafront, driven by plate-boundary dynamics. They will simulate this evolution using a regionalquasi-3D kinematic/tectonic-geomorphic-hydrologic coupled model that fully couples movementalong faults, mass distribution, magmatism, isostatic compensation and flexural deformationwith hydrology and surface geomorphic processes, including erosion and deposition. The extensionalfragmentation of the hydrological system will be studied and groundwater flow, necessary tosimulate the resulting development of springs, will be an integral part of the regional tectonic-geomorphic-hydrologic model..Modeled paleohydrologic histories will be tested against biotic data (aquatic biota inventories,microbial and macrofaunal DNA, and genetic divergence times) with island biogeography theory.The PIs will test for relations of hydrologic fragmentation chronology with endemic species andfor ecosystem diversity with spring resilience, as inferred from groundwater ages and climaticallydriven modeling. They will use these results to assess and improve their tectonic/paleohydrologic models.