Oxygen isotope analyses of diagenetic cements can provide detailed evidence of sedimentary burial processes and conditions, as the δ18O values of precipitating minerals reflect contemporaneous local δ18Owater and temperature conditions. Uncertainties in the timing and rates of pore water δ18O evolution in sedimentary basins can complicate interpretation of these records. Fracture-bridging (0.5–1 mm) quartz cements observed in sandstones of the Cretaceous Travis Peak Formation in the East Texas basin show clear growth-zoning by cathodoluminescence and contain detailed fluid inclusion records of temperature that make them excellent candidates for interrogating prolonged histories of basin temperature and the evolution of δ18O in basin pore water. New secondary ion mass spectrometer (SIMS) δ18Oquartz isotopic data from fluid inclusion-rich quartz bridges in Travis Peak sandstones record a steady increase of pore water δ18O values from ∼5 to 7‰ (VSMOW; Vienna Standard Mean Ocean Water) as the sandstone warms from ∼130 to 150 °C. To help evaluate whether this trend could be generated solely from local water-rock interactions in response to burial compaction, a one-dimensional closed system isotopic burial model was created to simulate how δ18Owater values change in a quartz-dominated sandstone during diagenesis. Using both directly measured and inferred rates of Travis Peak compaction, the magnitude of change in δ18Owater that we calculate from quartz bridge geochemistry cannot be reasonably modeled solely by local quartz mechanical compaction, pressure solution, and cementation processes, necessitating significant fluxes of silica and high-δ18O water from outside of the sandstones prior to maximum burial. This indicates that even units which appear surrounded by significant barriers to fluid flow (i.e., mudrock-bounded channel sandstones) may have been infiltrated and diagenetically modified by large fluxes of fluid on geologic time scales.

中文翻译：

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东德克萨斯州白垩纪特拉维斯峰组孔隙水氧同位素演化的历史

成岩水泥的氧同位素分析可以提供沉积埋藏过程和条件的详细证据，因为沉淀矿物的δ18O值反映了同期的局部δ18O水和温度条件。沉积盆地中孔隙水δ18O释放的时间和速率的不确定性可能会使这些记录的解释复杂化。在东得克萨斯盆地白垩纪特拉维斯峰组砂岩中观察到的裂缝桥接（0.5-1 mm）石英胶结物通过阴极发光显示清晰的生长带，并包含详细的温度流体包裹体记录，使其成为询问长期历史的极佳候选者。盆地温度与盆地孔隙水中δ18O的演化 新的二次离子质谱仪（SIMS）来自特拉维斯峰砂岩中富含流体包裹体的石英桥的δ18O同位素数据记录了随着砂岩变暖，孔隙水δ18O值从约5稳定增加到7‰（VSMOW；维也纳标准平均海洋水）从〜130至150°C。为了帮助评估这种趋势是否可以仅由局部水-岩相互作用响应于埋藏压实而产生，创建了一个一维封闭系统同位素埋藏模型，以模拟成岩过程中石英为主的砂岩中δ18 O水值如何变化。使用直接测量和推定的特拉维斯峰压实速率，我们仅通过局部石英机械压实，压力固溶和固结过程无法合理地模拟我们根据石英桥地球化学计算出的δ18Owater的变化幅度，在最大限度地埋葬之前，需要从砂岩外部产生大量的二氧化硅和高δ18O水通量。这表明，即使是看起来被流体流动的重大障碍所包围的单元（即，与泥岩结合的河道砂岩）也可能已被地质时间尺度上的大流量流体渗透并进行了渗流改正。