Lake-margin lacustrine carbonates of the Green River Formation, in the eastern Uinta basin of Colorado and Utah, occur interbedded with fluvial and shoreline-parallel sandstone and shale. Microbial bindstones were deposited in a saline-alkaline lake during and after the Early Eocene Climate Optimum (EECO) (52–50 million years ago) that is characterized by global hot-house conditions, elevated atmospheric CO2, and highly fluctuating climate conditions. The stratigraphic architecture, chemostratigraphy, and morphology of the microbialites and other associated carbonate beds can be related to these climatic conditions. Three facies associations are recognized in the carbonate units across the lake margin from upper littoral to lower sublittoral environments: facies association 1, delta proximal non-microbial carbonates, characterized by quartzose bioclastic, peloidal, intraclastic packstones and grainstones–rudstones, quartose peloid wackestones and sandy oil shale; facies association 2, microbialite associated non-microbial carbonates, composed of ostracod, ooilitic, peloidal packstones–grainstones and intraclastic packstones, grainstones and rudstones; and facies association 3, microbial carbonates, consisting of diverse forms of stromatolitic and thrombolitic lithofacies.Multiple scales of carbonate cyclicity are suggested by shifts of δ18O and δ13C stable isotopes and deepening-upward microbialite facies. High-frequency cycles, on the order of 1 to 5 m thickness, are characterized by positive shifts in stable isotopes and interpreted deepening trends from littoral to lower sublittoral conditions. Large-scale trends, on the order of tens to hundreds of meters thickness record long-term lake changes, including: 1) sparse microbialite deposition during initial fresh conditions in lake stage 1, with low macro-structure diversity and light δ18O and δ13C isotope values; 2) transitional lake stage 2 corresponding to moderate macro-structural diversity, large meter-scale biostromal and biohermal buildups, and a positive shift in δ18O and δ13C isotope values that suggest increasing saline and alkaline conditions; 3) a highly fluctuating lake stage 3 that contains the highest microbialite macro-structural diversity and marks the interval of heaviest δ18O and δ13C isotope values, suggesting the greatest lake restriction, and the highest salinity and alkalinity conditions; and 4) a rising lake stage 4 that marks the lowest microbialite macro-structure diversity and a reversal in trend of δ18O and δ13C isotope values, that indicate deepening and freshening conditions.

中文翻译：

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美国科罗拉多州和犹他州尤因塔盆地东部绿河组微生物岩形态的沉积系统和湖泊阶段控制

位于科罗拉多州和犹他州的 Uinta 盆地东部的格林河组湖缘湖相碳酸盐岩与河流和与海岸线平行的砂岩和页岩互层。在始新世早期气候最佳时期 (EECO)（52-5000 万年前）期间和之后，微生物结合岩沉积在盐碱湖中，其特征是全球温室条件、大气 CO2 升高和气候条件高度波动。微生物岩和其他相关碳酸盐岩床的地层结构、化学地层和形态可能与这些气候条件有关。在从上沿海环境到下沿海环境的整个湖边缘的碳酸盐单元中识别出三种相组合：相组合 1，三角洲近端非微生物碳酸盐岩，以石英质生物碎屑、球状、碎屑内碎屑岩和粒状砂岩为特征——砂岩、石英质球状泥岩和砂质油页岩；相组合 2，微生物岩伴生的非微生物碳酸盐岩，由介形体、鲕粒、球状粒状灰岩—粒状粒岩和碎屑粒状粒状灰岩、粒状粒状岩和粉状砂岩组成；和相组合 3，微生物碳酸盐，由多种形式的叠层石和凝块石岩相组成。δ18O 和 δ13C 稳定同位素的移动和向上加深的微生物岩相表明碳酸盐循环具有多种尺度。厚度为 1 至 5 m 的高频循环的特征是稳定同位素的正变化和解释的从沿海到低沿海条件的加深趋势。大趋势，几十到几百米的厚度记录了长期的湖泊变化，包括：1) 湖泊第一阶段初始新鲜条件下微生物岩沉积稀疏，宏观结构多样性低，δ18O 和 δ13C 同位素值较轻；2) 过渡湖泊阶段 2 对应于适度的宏观结构多样性，大米尺度的生物基质和生物群落，以及 δ18O 和 δ13C 同位素值的正变化，表明盐碱条件增加；3) 高度波动的湖泊阶段 3，微生物岩宏观结构多样性最高，标志着最重的 δ18O 和 δ13C 同位素值区间，表明湖泊限制最大，盐度和碱度条件最高；