Abstract The predominantly warm greenhouse climate and high global sea level during the Middle–Late Devonian resulted in fully marine conditions along the northern Gondwana margin, including the Iranian Plate. Over three-hundred meter-thick fossiliferous Middle-to Late Devonian carbonate deposits of the Bahram Formation in the Anarak region (western Central Iran) are composed of dark grey limestone, dolostone, and interbedded shale. Seventeen microfacies have been distinguished, which correspond to four depositional sub-environments, i.e., tidal flat, lagoon, shoal, and open marine. The Middle–Late Devonian carbonate deposits were deposited on a homoclinal carbonate ramp. Seven third-order depositional sequences are identified, apparently controlled by relative sea level change. Carbon and oxygen stable isotopes, and major and trace elements of micritic carbonate samples document details about the geochemical, palaeoenvironmental, and diagenetic processes; they also indicate that the carbonates underwent meteoric diagenesis within a semi-closed diagenetic system. The low concentrations of trace elements indicative of euxinic conditions, including Mo, Cr, V, and As, suggest well-oxygenated depositional environment. Carbon isotope values show a meaningful relationship to major sequence-stratigraphic key surfaces, with more negative values occurring at the sequence boundaries and positive values corresponding to maximum flooding surfaces.

中文翻译：

---

伊朗中西部阿纳拉克中-晚泥盆世碳酸盐岩（Bahram组）的古环境和层序地层分析

摘要 中-晚泥盆世主要是温暖的温室气候和高全球海平面，导致冈瓦纳大陆北部边缘包括伊朗板块的完全海洋条件。位于阿纳拉克地区（伊朗中西部）的巴赫拉姆组的中、晚泥盆世碳酸盐岩沉积层厚度超过 300 米，由深灰色石灰岩、白云岩和互层页岩组成。已区分出 17 个微相，对应于四个沉积亚环境，即潮坪、泻湖、浅滩和开阔海。中-晚泥盆世碳酸盐矿床沉积在同斜碳酸盐斜坡上。确定了七个三级沉积序列，显然受相对海平面变化的控制。碳氧稳定同位素，泥晶碳酸盐样品的主要和微量元素记录了地球化学、古环境和成岩过程的详细信息；它们还表明，碳酸盐岩在一个半封闭的成岩系统中经历了大气成岩作用。低浓度的微量元素（包括 Mo、Cr、V 和 As）表明了富氧条件，表明沉积环境充氧良好。碳同位素值显示出与主要层序地层关键表面的有意义的关系，更多的负值出现在层序边界处，而正值对应于最大洪水表面。低浓度的微量元素（包括 Mo、Cr、V 和 As）表明了富氧条件，表明沉积环境充氧良好。碳同位素值显示出与主要层序地层关键表面的有意义的关系，更多的负值出现在层序边界处，而正值对应于最大洪水表面。低浓度的微量元素（包括 Mo、Cr、V 和 As）表明了富氧条件，表明沉积环境充氧良好。碳同位素值显示出与主要层序地层关键表面的有意义的关系，更多的负值出现在层序边界处，而正值对应于最大洪水表面。