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

大盆地南部是北美最干旱的地区之一。它几乎没有常年溪流，但却有1,000处泉水。这些泉水是沙漠海洋中的水生生物岛屿.值得注意的是，这些孤立的泉水中有许多包含了多样化的水生生态系统，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泉水是常年排水系统的残留物，而存在的地方性物种需要百万年的遗传差异，这证明了至少有一些泉水在地质时间尺度上从未干涸过。这是一个扩大已经很大的区域水文地理数据库的项目，并利用新的和先前存在的数据来测试东南大盆地的构造和古水文演变模型。PI将集中在两个时间尺度上：从晚中新世到现在的区域的伸展断裂和冰川/间冰期气候循环。广泛的工作已经完成，以了解该地区的伸展历史，它开始于研究区的东部，在14 Ma左右，并向西迁移到内华达山脉前沿，由板块边界动力学驱动。他们将使用一个区域准三维运动学/构造-地貌-水文耦合模型来模拟这种演变，该模型将沿断层的运动、质量分布、岩浆作用、均衡补偿和挠曲变形与水文和地表地貌过程（包括侵蚀和沉积）完全耦合。将研究水文系统的扩展破碎情况，模拟由此产生的泉水发展所必需的地下水流将成为区域构造-地貌-水文模型的一个组成部分。模拟的古水文历史将根据生物数据（水生生物区系清单、微生物和大型动物DNA以及遗传分化时间）与岛屿地理学理论进行测试。PI将测试水文破碎年表与地方性物种的关系，以及生态系统多样性与春季恢复力的关系，如从地下水年龄和气候驱动的建模中推断的那样。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.