Lithostratigraphy and carbonate microfacies across the Permian–Triassic boundary near Julfa (NW Iran) and in the Baghuk Mountains (Central Iran)
Lithostratigraphy and carbonate microfacies across the Permian–Triassic boundary near Julfa (NW Iran) and in the Baghuk Mountains (Central Iran)
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DOI：
10.1007/s10347-013-0366-0
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发表时间：
2014-01
期刊：
影响因子：
1.8
通讯作者：
L. Leda;D. Korn;A. Ghaderi;V. Hairapetian;U. Struck;W. Reimold
中科院分区：
文献类型：
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作者：
L. Leda;D. Korn;A. Ghaderi;V. Hairapetian;U. Struck;W. Reimold
Julfa（伊朗西北部）和Abadeh（伊朗中部）地区的二叠纪-三叠纪边界剖面显示出一系列三个特征岩石单元：(1) 顶部有大灭绝层的Paratirolites石灰岩，(2)“边界粘土”，以及(3)最早的三叠纪Elikah组，其底部有牙形刺P-Tr边界。碳酸盐微相揭示了在Julfa附近的部分，在Paratirolites灰岩内发生了相变，内碎屑、铁锰结壳和生物结壳的数量不断增加。碳酸盐累积量下降发生在装置顶部，部分区域有海绵堆积石，最终导致碳酸盐工厂完全消亡。两个地区的“界土”的演替有所不同； Julfa 地区存在薄薄的一层海绵堆积岩，Abadeh 地区则存在可能是无机来源的“方解石扇”。随着微生物碳酸盐在 Elikah 组底部的沉积，二叠纪晚期的骨架碳酸盐工厂得到了恢复，其中以密层状粘结岩、带有亮晶方解石球的浮石和类长粒砂岩/浮石为主。
Permian–Triassic boundary sections in the Julfa (NW Iran) and Abadeh (Central Iran) regions display a succession of three characteristic rock units, (1) theParatirolitesLimestone with the mass extinction horizon at its top, (2) the ‘Boundary Clay’, and (3) the earliest Triassic Elikah Formation with the conodont P–Tr boundary at its base. The carbonate microfacies reveals a facies change, in the sections near Julfa, within theParatirolitesLimestone with an increasing number of intraclasts, Fe–Mn crusts, and biogenic encrustation. A decline in carbonate accumulation occurs towards the top of the unit with a sponge packstone in the sections, and finally resulting in a complete demise of the carbonate factory. The succession of the ‘Boundary Clay’ differs in the two regions; thin horizons of sponge packstone are present in the Julfa region and ‘calcite fans’ of probably inorganic origin in the Abadeh Region. The skeletal carbonate factory of the Late Permian was restored with the deposition of microbial carbonates at the base of the Elikah Formation, where densely laminated bindstone, floatstone with sparry calcite spheres, and oncoid wackestone/floatstone predominate.