Carbonate archives record a brief snapshot of the ambient Earth’s surface conditions at their deposition. However, the geologically reasonable extraction and interpretation of geochemical proxy data from ancient, diagenetically altered rock archives is fraught with problems. Three issues stand out: the dichotomy between petrographic and geochemical alteration; the lack of quantitative age constraints for specific diagenetic phases resulting in a poorly constrained admixture of local, basin-wide and over-regional (far-field) features; and an often insufficient understanding of the temperatures and compositions of diagenetic fluids. Here, the archive of Devonian marine limestones exposed to multiple far-field diagenetic events is used as an example to explore the above-listed issues. Methods applied include petrography, micro XRF, fluid inclusion data, clumped isotopes, δC and δO isotopes, Sr/Sr ratios and quartz trace element data. Devonian limestones studied here were overprinted by two cross-cutting regional fault zones (T ≈ 230 °C) by multiple events between the Variscan Orogeny and the late Paleogene. The following processes are recorded: (i) protolith deposition and partial dolomitisation during rapid burial in the Middle/Late Devonian (T ≈ 180 °C); (ii) deep burial to 6.5 km and tectonic/hydrothermal overprint during the Variscan Orogeny in the Carboniferous (T ≈ 90–230 °C); (iii) rapid uplift to 1–2 km burial depth at the end of the Variscan Orogeny and hypogene karstification (T ≈ 50 to 100 °C) initiated by regional geology in the Permian/Triassic; (iv) tectonic/hydrothermal overprint during the opening of the Proto-Atlantic Ocean between the Early Jurassic and the Early Cretaceous (T ≈ 50 to 130 °C); (v) tectonic/hydrothermal overprint including renewed hypogene karstification and hydrothermal calcite cement precipitation (T ≈ 50 to 180 °C) during Alpine Orogeny between the Late Cretaceous and late Paleogene. Despite this complex series of diagenetic events, the protolith limestones largely preserved their respective Middle/Late Devonian dissolved inorganic carbon (DIC) and Sr/Sr signatures. This study documents that geochemical proxy data, placed into their petrographic, paleotemperature, and local to over-regional context, significantly increases the ability to extract quantitative information from ancient carbonate rock archives. Research shown here has wider relevance for carbonate archive research in general.

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更好地理解复杂碳酸盐档案的地球化学代理记录

碳酸盐档案记录了沉积时地球表面环境的简要快照。然而，从古代成岩蚀变岩石档案中对地球化学代理数据进行地质上合理的提取和解释充满了问题。三个问题很突出：岩石学和地球化学蚀变之间的二分法；缺乏对特定成岩阶段的定量年龄限制，导致局部、盆地范围和超区域（远场）特征的混合约束不良；对成岩流体的温度和成分的了解往往不足。这里，以经历过多次远场成岩事件的泥盆纪海相灰岩档案为例来探讨上述问题。应用的方法包括岩相学、显微 XRF、流体包裹体数据、簇同位素、δ13C 和 δ18O 同位素、Sr/Sr 比率和石英微量元素数据。这里研究的泥盆纪石灰岩被瓦里斯造山运动和古近纪晚期之间的多次事件所覆盖的两个交叉区域断层带（T ≈ 230 °C）所覆盖。记录了以下过程：（i）中/晚泥盆世（T ≈ 180 °C）快速埋藏过程中的原岩沉积和部分白云石化； (ii) 石炭纪瓦里斯造山运动期间深埋至 6.5 公里的构造/热液叠印（T ≈ 90–230 °C）； (iii) 在瓦里斯造山运动末期，二叠纪/三叠纪区域地质引发的深生岩溶作用（T ≈ 50 至 100 °C）迅速抬升至 1-2 公里埋藏深度； (iv) 早侏罗世和早白垩世之间原大西洋开放期间的构造/热液叠印（T ≈ 50 至 130 °C）； (v) 构造/热液叠加，包括晚白垩世和晚古近纪之间高山造山运动期间重新发生的深生岩溶作用和热液方解石胶结物沉淀（T ≈ 50 至 180 °C）。尽管发生了这一系列复杂的成岩事件，原岩石灰岩在很大程度上保留了各自的中/晚泥盆世溶解无机碳（DIC）和Sr/Sr特征。这项研究记录了将地球化学代理数据放入岩相学、古温度和局部到跨区域背景中，显着提高了从古代碳酸盐岩档案中提取定量信息的能力。这里展示的研究总体上与碳酸盐档案研究具有更广泛的相关性。