Abstract More than a dozen hydrocarbon seep‐carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault‐hosted or serpentine diapir‐related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three‐stage development that recorded the evolution of fluids through reducing–oxidizing–reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH 4 , H 2 S) through seafloor sediments, as indicated by Fe‐rich detrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (δ 13 C as low as −35.5‰ PDB; δ 18 O as low as −10.8‰ PDB). Mega‐invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with δ 13 C values as low as −43.7‰ PDB, elevated δ 18 O (up to +2.3‰ PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late‐stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore‐associated Mn‐rich cement phases with bright cathodoluminescent patterns, and negative δ 18 O signatures (as low as −14‰ PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep‐carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono‐sedimentary regimes and time–temperature‐dependent burial diagenesis.

K. A. Campbell

J. D. Farmer

D. Des Marais

Geofluids

GEOFLUIDS 是一份经过同行评审的开放获取期刊，为与流体在地壳的矿物学、化学和结构演化中的作用相关的原创研究和评论提供了一个论坛。其明确目标是在开展地流体研究的各个子学科范围内传播思想。为此，鼓励作者强调其研究的跨学科相关性和国际影响。还鼓励作者尽可能让其他子学科的读者能够访问他们的工作。GEOFLUIDS 强调整个地壳中地下流体的化学、微生物和物理方面。 GEOFLUIDS 涵盖地下水、陆地或海底地热流体、盆地盐水、石油、变质水或岩浆流体的研究。

GEOFLUIDS is a peer-reviewed open-access journal that provides a forum for original research and reviews related to the role of fluids in the mineralogy, chemistry, and structural evolution of the Earth's crust. Its explicit aim is to disseminate ideas across various sub-disciplines involved in geofluid research. Authors are encouraged to highlight the interdisciplinary relevance and international impact of their work, and to present their findings in a manner accessible to readers from other sub-disciplines. GEOFLUIDS emphasizes the chemical, microbial, and physical aspects of subsurface fluids throughout the crust, covering studies on groundwater, terrestrial or submarine geothermal fluids, basin brines, petroleum, metamorphic waters, and magmatic fluids.

GEOFLUIDS 是一本经过同行评审的开放获取期刊，专注于流体在地壳中的矿物学、化学和结构演化方面的原创研究和评论。期刊的目标是传播与地流体研究相关的各个子学科的思想，鼓励作者强调其研究的跨学科相关性和国际影响力。同时，作者也被鼓励以便于其他子学科的读者理解的方式呈现他们的工作。GEOFLUIDS 强调地下流体在整个地壳中的化学、微生物和物理特性，涵盖地下水、陆地或海底地热流体、盆地盐水、石油、变质水和岩浆流体等研究。

Category	Quartile
地球科学	4
地球科学, 地球化学与地球物理	4
地球科学, 地质学	4

Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments

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