The well-exposed outcrops of the Bujan, northern Abadeh, and Varkan stratigraphic sections of the Qom Formation in the Iranian part of the “northeastern margin” of the Tethyan Seaway were characterized by abundant biogenic components dominated by foraminifers, coralline red algae, and corals. The Qom Formation is Rupelian–Chattian in age in the study areas. Based on the field investigations, depositional textures, and dominant biogenic components, fifteen (carbonate and terrigenous) facies were identified. These facies can be grouped into four depositional environments: open marine, open lagoon, restricted lagoon, and continental braided streams. The marine facies were deposited on a ramp-type platform. The euphotic inner ramp was characterized mainly by imperforate foraminifera, with co-occurrence of some perforate taxa. These facies passed basinward into a mesophotic (middle) ramp with Neorotalia packstone (F5), coral, coralline algae, perforate foraminiferal packstone (F4), and coral patch reefs (F7). The deeper, oligophotic ramp facies were marly packstones with planktonic and hyaline benthic foraminifera, including large lepidocyclinids and nummulitids. The abundance of perforate foraminifera and the absence of facies indicating restricted lagoonal or intertidal settings suggest that the Varkan section was deposited mainly in open marine settings with normal salinity. The prevalence of larger benthic foraminiferal and red algal assemblages, together with the coral facies, indicates that carbonate production took place in tropical–subtropical waters.

特提斯海道“东北边缘”伊朗部分库姆组Bujan、Abadeh 北部和Varkan 地层剖面出露良好的露头，其特征是富含以有孔虫、珊瑚红藻和珊瑚为主的生物成因成分. 研究区的库姆组年龄为 Rupelian-Chattian。根据实地调查、沉积结构和主要生物成分，确定了 15 个（碳酸盐岩和陆源）相。这些相可分为四种沉积环境：开阔海相、开阔泻湖、受限泻湖和大陆辫状溪流。海相沉积在斜坡型平台上。光亮的内坡主要以无孔有孔虫为特征，同时存在一些有孔类群。Neorotalia Packstone (F5)、珊瑚、珊瑚藻、穿孔有孔虫 Packstone (F4) 和珊瑚斑礁 (F7)。更深的、寡光的斜坡相是具有浮游和透明底栖有孔虫的泥灰岩，包括大型鳞环类和麻木类。大量的有孔虫和缺乏指示受限泻湖或潮间带环境的相表明 Varkan 剖面主要沉积在具有正常盐度的开阔海洋环境中。较大的底栖有孔虫和红藻组合以及珊瑚相的盛行表明碳酸盐生产发生在热带-亚热带水域。