Carbonate microbialites in lakes can serve as valuable indicators of past environments, so long as the biogenicity and depositional setting of the microbialite can be accurately determined. Late Pleistocene to Early Holocene frondose draping tufa deposits from Winnemucca Dry Lake (Nevada, USA), a subbasin of pluvial Lake Lahontan, were examined in outcrop, petrographically, and geochemically to determine whether microbially induced precipitation is a dominant control on deposition. These observations were compared to modern, actively accumulating microbialites from Fayetteville Green Lake (New York, USA) using similar methods. In addition, preserved microbial DNA was extracted from the Lahontan tufa and sequenced to provide a more complete picture of the microbial communities. Tufas are texturally and geochemically similar to modern thrombolitic microbialites from Fayetteville Green Lake, and the stable isotopic composition of organic C, N, inorganic C, and O supports deposition associated with a lacustrine microbial mat environment dominated by photosynthetic processes. DNA extraction and sequencing indicate that photosynthetic microbial builders were present during tufa deposition, primarily Chloroflexi and Proteobacteria with minor abundances of Cyanobacteria and Acidobacteria. Based on the sequencing results, the depositional environment of the tufas can be constrained to the photic zone of the lake, contrasting with some previous interpretations that put tufa formation in deeper waters. Additionally, the presence of a number of mesothermophilic phyla, including Deinococcus–Thermus, indicates that thermal groundwater may have played a role in tufa deposition at sites not previously associated with groundwater influx. The interpretation of frondose tufas as microbially influenced deposits provides new context to interpretations of lake level and past environments in the Lahontan lake basins.

中文翻译：

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微生物影响的湖相碳酸盐：晚第四纪Lahontan凝灰岩与纽约州费耶特维尔格林湖的现代凝块岩的比较。

湖泊中的碳酸盐微纤长岩可以作为过去环境的重要指标，只要可以准确确定微纤长岩的生物成因和沉积环境即可。从露头湖Lahontan的一个子盆地Winnemucca Dry Lake（美国内华达州）更新世晚期至全新世早期氟垂悬的石灰岩沉积物，在露头，岩相和地球化学方面进行了研究，以确定微生物引起的降水是否是沉积的主要控制因素。使用相似的方法，将这些观察结果与来自费耶特维尔绿湖（美国纽约）的现代，积极积累的微辉石进行了比较。此外，从Lahontan凝灰岩中提取了保存的微生物DNA并进行了测序，以提供微生物群落的更完整图片。凝灰岩在质地和地球化学上类似于费耶特维尔绿湖地区的现代血栓形成的微辉石，有机碳，氮，无机碳和氧的稳定同位素组成支持了与以光合作用为主的湖泊微生物垫环境相关的沉积。DNA提取和测序表明，在石灰沉积过程中存在光合微生物增效剂，主要是绿弯菌门和变形菌有轻微的丰度蓝藻和酸杆菌门。根据测序结果，可以将石灰石的沉积环境限制在湖泊的光合带，这与先前将石灰石形成在更深水域中的一些解释形成了对比。此外，包括嗜热菌-嗜热菌在内的许多中等嗜温菌门的存在表明，热地下水可能在以前与地下水流入无关的地点的石灰石沉积中发挥了作用。将弗朗西斯的石灰石解释为受微生物影响的沉积物，为解释拉洪坦湖盆地的湖面水平和过去的环境提供了新的背景。