Depositional process, sediment provenance, and paleotopography are critical to paleogeographic reconstruction during the coeval Laramide and Sevier orogenies in the Cordillera orogenic system. Here we conduct lithofacies analysis, sediment provenance, and paleoelevation studies in the fluvial lower Paleogene Fort Union and the main body of the Wasatch formations in the center of the greater Green River Basin in order to reconstruct paleogeography. The depositional environment changed from low-energy floodplains and associated meandering river during the Paleocene to braided rivers during the earliest Eocene. The lowermost Eocene strata have more Precambrian basement-derived feldspar grains compared to the Paleocene strata. This change in sediment provenance was associated with the change to dominant northwestward paleoflow direction, suggesting major uplift of the Laramide Uinta Mountains during the earliest Eocene. The δ18O values of authigenic carbonates were stable during the early Paleocene, but decreased gradually from −10 permil during the late Paleocene to −18 permil during the earliest Eocene, suggesting the lack of highland precipitation in the basin catchment during the early Paleocene, and significant surface uplift and arrival of highland precipitation from the Uinta Mountains during the earliest Eocene. The reconstructed paleoelevation of the Uinta Mountains was at least 3 km, possibly greater than 3.5 km, and the paleoelevation of the greater Green River Basin floor was at most 1 km, and the paleorelief between the greater Green River Basin and Uinta Mountains was ∼ 2 km during the earliest Eocene. Our record of the earliest Eocene establishment of high topography of the Uinta Mountains through renewed uplift is 4 to 6 Myr older than previously thought. If the carbonate cements in the Fort Union Formation record the isotope compositions of surface water from the Sevier orogen, their high δ18O values likely suggest that the Sevier orogen had rugged topography during the Paleocene.

中文翻译：

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美国怀俄明州西南部古近纪大格林河流域早期沉积环境、沉积物来源和氧同位素古高度测量

沉积过程、沉积物来源和古地形对于科迪勒拉造山系统中同时代的拉拉米德和塞维尔造山运动期间的古地理重建至关重要。在这里，我们在大格林河流域中心的河流下游古近系堡垒联盟和 Wasatch 地层主体中进行岩相分析、沉积物来源和古海拔研究，以重建古地理。沉积环境从古新世的低能量漫滩和相关的蜿蜒河流转变为最早始新世的辫状河。与古新世地层相比，最下部的始新世地层具有更多的前寒武纪基底衍生的长石颗粒。这种沉积物来源的变化与主导的西北古流向的变化有关，表明在最早的始新世 Laramide Uinta 山脉发生了重大隆起。自生碳酸盐的δ18O值在早古新世稳定，但从晚古新世的-10 permil逐渐下降到最早始新世的-18 permil，表明早古新世盆地流域缺乏高原降水，显着最早的始新世 Uinta 山脉的地表隆起和高原降水的到来。重建的尤因塔山脉古海拔至少为 3 公里，可能大于 3.5 公里，大格林河流域地底古海拔最多为 1 公里，大格林河流域与尤因塔山脉之间的古地形为 ∼ 2公里在最早的始新世。我们记录的最早始新世通过重新隆起建立 Uinta 山脉高地的记录比以前认为的要早 4 到 6 Myr。如果 Fort Union 地层中的碳酸盐胶结物记录了 Sevier 造山带地表水的同位素组成，它们的高 δ18O 值可能表明 Sevier 造山带在古新世具有崎岖的地形。