The end-Permian mass extinction (EPME) is marked by a major crisis in Phanerozoic carbonate systems that likely reflected a large-scale change in ocean chemistry and have repercussions during its aftermath. At the basal Triassic distal carbonate ramp of Central Iran, unusual non-skeletal carbonates have been deposited, so-called "crystal layers" or "carbonate crusts". We show here that those carbonates are sponge microbial buildups (SMB) built by digitate stromatolite columns, small aragonitic overgrowth and sponges. They are very similar to the SMBs recently described in South Armenia. All the SMB cropping out along the Cimmerian margin of the Neotethys are interpreted as (a) short bio-event(s) and belong to a Time Specific Facies (TSF). In this study, we mainly focus on two well-known Permian-Triassic boundary and post extinction localities: the Kuh e Hambast section east of Abadeh city and the more distal Shahreza section near Isfahan. In both sections, the extinction horizon belongs to the top of the latest Permian Paratirolites limestone. At Kuh e Hambast, the overlying so-called “boundary clay” is conformably overlain by basal Triassic dark lime mudstone containing four successive levels of decimeter to meter scale elongated to cup- shaped mounds made of branching columnar stromatolites. Sponge fibers, possible keratose demosponge, are widely present in the lime mudstone matrix. At the Shahreza section, above the extinction level, five SMB levels are present overlying each other in the lower 20 m of the basal Triassic platy limestone. The first, latest Permian in age, is made of micro-laminated calcite crystal bundles interpreted as digitate stromatolite, with calcite-cemented fibrous interspaces in a micritic clump. The fibers and spicules in micritic matrix are considered as sponge fossils. Some overlying SMB consist of thrombolite domes, and other buildups of more complex structure, show again micro-laminated calcite crystal bundles. A mound at the top is characterized by coalescent spheroids possibly made of a keratose sponge fibers mesh.

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从灭绝到基础三叠纪的海绵收购：伊朗中部微生物堆积的记录

二叠纪末期生物大灭绝（EPME）的特征是生代碳酸盐体系发生重大危机，这很可能反映了海洋化学的大规模变化，并在其后果中产生了影响。在伊朗中部的基底三叠纪末段碳酸盐斜坡上，沉积了异常的非骨架碳酸盐，即所谓的“晶体层”或“碳酸盐结壳”。我们在这里表明，这些碳酸盐是指由数字化层状叠层石柱，少量文石长成和海绵构成的海绵微生物堆积物（SMB）。它们与南亚美尼亚最近描述的中小型企业非常相似。沿新特提斯的西密尔边缘切出的所有SMB都被解释为（a）短生物事件，并且属于特定时间相（TSF）。在这项研究中，我们主要关注两个著名的二叠纪-三叠纪边界和灭绝后的地点：阿巴德市以东的Kuh e Hambast段和伊斯法罕附近的Shahreza较远段。在这两个区域中，灭绝层都属于最新的二叠纪副滑石石灰岩的顶部。在Kuh e Hambast，上覆的所谓的“边界黏土”被三叠纪的深色深色石灰岩泥岩覆盖，该泥岩包含四个连续水平的分米至米级，延伸至由分支的柱状叠层石制成的杯状土堆。海绵纤维，可能的角蛋白脱脂，广泛存在于石灰泥岩基质中。在灭绝高度以上的Shahreza断面中，基底三叠纪板状灰岩的下部20 m中存在五个SMB高度，彼此重叠。第一个，最新的二叠纪，由微层压方解石晶体束制成，被解释为指状叠层石，方解石胶结的纤维状空隙形成在微晶团块中。微晶基质中的纤维和针状体被认为是海绵化石。一些上覆的SMB由血栓石穹顶组成，其他结构更复杂的堆积物再次显示出微层压的方解石晶体束。顶部的土墩的特征是聚结的球状体，可能是由角蛋白海绵纤维网制成的。