The shallow marine and subaerial sedimentary and hydrothermal rocks of the ~3.48 billion‐year‐old Dresser Formation are host to some of Earth's oldest stromatolites and microbial remains. This study reports on texturally distinctive, spherulitic barite micro‐mineralization that occur in association with primary, autochthonous organic matter within exceptionally preserved, strongly sulfidized stromatolite samples obtained from drill cores. Spherulitic barite micro‐mineralization within the sulfidized stromatolites generally forms submicron‐scale aggregates that show gradations from hollow to densely crystallized, irregular to partially radiating crystalline interiors. Several barite micro‐spherulites show thin outer shells. Within stromatolites, barite micro‐spherulites are intimately associated with petrographically earliest dolomite and nano‐porous pyrite enriched in organic matter, the latter of which is a possible biosignature assemblage that hosts microbial remains. Barite spherulites are also observed within layered barite in proximity to stromatolite layers, where they are overgrown by compositionally distinct (Sr‐rich), coarsely crystalline barite that may have been sourced from hydrothermal veins at depth. Micro‐spherulitic barite, such as reported here, is not known from hydrothermal systems that exceed the upper temperature limit for life. Rather, barite with near‐identical morphology and micro‐texture is known from zones of high bio‐productivity under low‐temperature conditions in the modern oceans, where microbial activity and/or organic matter of degrading biomass controls the formation of spherulitic aggregates. Hence, the presence of micro‐spherulitic barite in the organic matter‐bearing Dresser Formation sulfidized stromatolites lend further support for a biogenic origin of these unusual, exceptionally well‐preserved, and very ancient microbialites.

中文翻译：

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微球状重晶石与有机物质结合形成的34.8亿年前的德莱赛地层，皮尔巴拉·克拉顿的硫化层云母中。

拥有约34.8亿年历史的德莱瑟组的浅层海洋和陆上沉积和热液岩石是一些地球上最古老的叠层石和微生物残留物的宿主。这项研究报告了从钻芯中获得的特殊保存的，强烈硫化的叠层石样品中，质地独特，球状的重晶石微矿化与初级原生质有机物相关的现象。硫化的叠层石中的球状重晶石微矿化通常形成亚微米级的聚集体，这些聚集体表现出从中空到致密结晶，不规则到部分辐射的晶体内部的渐变。一些重晶石微球体显示出薄的外壳。在叠层石中，重晶石微球石与岩石学上最早的白云石和富含有机物的纳米多孔黄铁矿有密切的联系，后者是一种可能的生物特征集合体，具有微生物残留。在叠层石层附近的层状重晶石中也观察到重晶石球晶，在重晶石球晶中，它们是由成分独特的（富含锶），粗晶的重晶石长满的，这些重晶石可能来自深部的热液脉。超过寿命上限的水热系统无法得知如此处报道的微球状重晶石。相反，在现代海洋中，在低温条件下，具有高生物生产力的区域已知形态和微观结构相近的重晶石，微生物活性和/或降解生物质的有机物控制着球状聚集体的形成。因此，含有机物的德莱斯特地层硫化的叠层石中存在微球状重晶石，为这些异常，保存得很好且非常古老的微菱沸石的生物成因提供了进一步的支持。