Recent studies of continental carbonates revealed that carbonates with similar fabrics can be formed either by biotic, biologically‐induced, biologically‐influenced or purely abiotic processes, or a combination of all. The aim of this research is to advance knowledge on the formation of carbonates precipitated (or diagenetically altered) in extreme, continental environments by studying biotic versus abiotic mechanisms of crystallization, and to contribute to the astrobiology debate around terrestrial analogues of Martian extreme environments. Both fossil (upper Pleistocene to Holocene) and active carbonate spring mounds from the Great Artesian Basin (South Australia) have been investigated. These carbonates consist of low‐Mg to high‐Mg calcite tufa. Four facies have been described: (i) carbonate mudstone/wackestone; (ii) phytohermal framestone/boundstone; (iii) micrite boundstone; and (iv) coarsely crystalline boundstone. The presence of filaments encrusted by micrite, rich in organic compounds, including ultraviolet‐protectants, in phytohermal framestone/boundstone and micrite boundstone is clear evidence of the existence of microbial mats at the time of deposition. In contrast, peloidal micrite, despite commonly being considered a microbial precipitate, is not directly associated with filaments in the Great Artesian Basin mounds. It has probably formed from nanocrystal aggregation on colloid particulate. Thus, where biofilms have been documented, it is likely that bacteria catalyzed the development of fabrics. It is less certain that microbes induced calcium carbonate precipitation elsewhere. Trace elements, including rare earth element distribution from laminated facies, highlight strongly evaporative settings (for example, high Li contents). Carbon dioxide degassing and evaporation are two of the main drivers for an increase in fluid alkalinity, resulting in precipitation of carbonates. Hence, although the growth of certain fabrics is fostered by the presence of microbial mats, the formation of carbonate crystals might be independent from it and mainly driven by extrinsic factors. More generally, biological processes may be responsible for fabric and facies development in micritic boundstone whilst micrite nucleation and growth are driven by abiotic factors. Non‐classical crystallization pathways (aggregation and fusion of nanoparticles from nucleation clusters) may be more common than previously thought in spring carbonate and this should be carefully considered to avoid misinterpretation of certain fabrics as by‐products of life. It is proposed here that the term ‘organic‐compound catalyzed mineralization’ should be used for crystal growth in the presence of organic compounds when dealing with astrobiological problems. This term would account for the possibility of multiple crystallization pathways (including non‐classical crystallization) that occurred directly from an aqueous solution without the direct influence of microbial mats.

中文翻译：

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大自流盆地（澳大利亚）春季丘陵碳酸盐岩中的结晶途径：对地球及其他地区生命特征的影响

近期对大陆碳酸盐的研究表明，具有相似结构的碳酸盐可以通过生物，生物诱导，生物影响或纯非生物过程或全部过程形成。这项研究的目的是通过研究生物与非生物的结晶机制，来增进对极端大陆环境中沉淀（或非定理地改变）碳酸盐形成的认识，并为围绕火星极端环境的陆地类似物的天文生物学辩论做出贡献。来自大自流盆地（南澳大利亚）的化石（上更新世至全新世）和活性碳酸盐春季土丘都得到了研究。这些碳酸盐由低镁到高镁方解石石灰石组成。已经描述了四个相：（i）碳酸盐泥岩/粗砂岩；（ii）植物热框架石/界石；（iii）微晶界石；（iv）粗晶界石。在植皮框架石/胶结石和微晶石胶结石中存在由微晶包裹的细丝，富含有机化合物，包括紫外线防护剂，这清楚地证明了沉积时微生物垫的存在。相反，尽管通常被认为是微生物沉淀物，但倍体微晶石与大自流盆地土丘中的细丝并不直接相关。它可能是由胶体微粒上的纳米晶体聚集形成的。因此，在已记录生物膜的地方，细菌很可能催化了织物的发展。微生物在其他地方引起碳酸钙沉淀的可能性还不太确定。微量元素，包括层状相中稀土元素的分布，突出了强烈的蒸发环境（例如，高Li含量）。二氧化碳的脱气和蒸发是增加流体碱度，导致碳酸盐沉淀的两个主要驱动力。因此，尽管某些织物的生长是由于微生物垫的存在而促进的，但碳酸盐晶体的形成可能与其无关，并且主要是由外部因素驱动的。更一般而言，生物过程可能是造成微晶胶结岩中织物和相发育的原因，而微晶核的形成和生长是由非生物因素驱动的。非经典的结晶途径（来自成核簇的纳米颗粒的聚集和融合）可能比以前在春季碳酸盐中所认为的更为普遍，因此应谨慎考虑这一点，以免将某些织物误解为生命的副产品。在此建议，在处理天体生物学问题时，术语“有机化合物催化的矿化”应用于存在有机化合物的晶体生长。该术语将解释由水溶液直接发生而没有微生物垫直接影响的多种结晶途径（包括非经典结晶）的可能性。在此建议，在处理天体生物学问题时，术语“有机化合物催化的矿化”应用于存在有机化合物的晶体生长。该术语将解释由水溶液直接发生而没有微生物垫直接影响的多种结晶途径（包括非经典结晶）的可能性。在此建议，在处理天体生物学问题时，术语“有机化合物催化的矿化”应用于存在有机化合物的晶体生长。该术语将解释直接从水溶液中发生多种结晶途径（包括非经典结晶）的可能性，而没有微生物垫的直接影响。