Abstract Owing to their isolated oceanic setting, atoll-type carbonates are well suited for documenting carbonate deposition and diagenesis in oceanic environments away from continental influence. The atoll-type Dalnegorsk limestone (Taukha Terrane, Russian Far East), deposited in the gigantic but poorly-documented Panthalassa Ocean, preserves a complete record of the diagenetic evolution of an Upper Triassic system, out of the Tethyan domain. To study the diagenesis of this carbonate system, we developed a novel analytical workflow, combining cathodoluminescence petrography with high-resolution analyses of environmental proxies in calcitic cements (δ18O, δ13C, REEY, trace and minor/major elements) and in situ U–Pb dating of calcite cements to precisely reconstruct the chronology of the diagenetic events. We combined these lines of evidence to establish a model of atoll evolution, from deposition to dismantling, based on 10 identified diagenetic episodes. The Dalnegorsk limestone records emergence at the Norian-Rhaetian transition, marked by meteoric and evaporitic cements, followed by dismantling of the atoll edges after drawning in the Early Jurassic. Neomorphism of calcitic shells occurred at the onset of calcitic sea conditions during the Toarcian-Bajocian. The limestone was thoroughly cemented during the Middle/Late Jurassic, and accreted within the Taukha Terrane during the Late Jurassic/Early Cretaceous. Accretion resulted in fracturing, brecciation, and recrystallisation of the Dalnegorsk limestone. This model is potentially applicable to any similar atoll system, irrespective of age. The evidence presented here extends our knowledge of Late Triassic environments in the Panthalassa Ocean, and more generally, our understandingg of mid-oceanic limestone formation and evolution.

中文翻译：

---

δ18O、δ13C、微量元素和 REE 原位测量与 U-Pb 年龄相结合，重建 Panthalassa 洋上三叠统环礁型碳酸盐岩的成岩作用

摘要 由于其孤立的海洋环境，环礁型碳酸盐非常适合记录远离大陆影响的海洋环境中的碳酸盐沉积和成岩作用。环礁型达尔内戈尔斯克石灰岩（Taukha Terrane，俄罗斯远东地区）沉积在巨大但记录不足的 Panthalassa 洋中，保留了特提斯域外上三叠统成岩演化的完整记录。为了研究这个碳酸盐系统的成岩作用，我们开发了一种新的分析工作流程，将阴极发光岩相学与方解石胶结物（δ18O、δ13C、REEY、痕量和微量/主要元素）和原位 U-Pb 中环境代理的高分辨率分析相结合方解石胶结物的年代测定以精确重建成岩事件的年代。我们结合这些证据，基于 10 个已确定的成岩事件，建立了一个环礁演化模型，从沉积到拆除。Dalnegorsk 石灰岩记录了 Norian-Rhaetian 过渡时期的出现，以流星和蒸发胶结物为标志，随后在早侏罗世绘制后环礁边缘被拆除。Toarcian-Bajocian 方解石海条件开始时方解石壳的新形貌发生。石灰岩在中/晚侏罗世被彻底胶结，并在晚侏罗世/早白垩世在 Taukha 地体内增生。增生导致 Dalnegorsk 石灰岩破裂、角砾化和再结晶。无论年龄如何，该模型都可能适用于任何类似的环礁系统。