نویسندگان
1 استادیار گروه زمینشناسی، دانشکده علومپایه، دانشگاه لرستان، خرمآباد، ایران
2 دانشآموخته دکترا، گروه زمینشناسی، دانشکده علومپایه، دانشگاه لرستان، خرمآباد، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
One of the most complete sedimentary successions of the Upper Permian-Lower Triassic is located at Zal section, in NW Iran. This section was examined in order to determine the microfacies changes and depositional environment in uppermost Permian and through the entire Lower Triassic. The microfacies change from deep deposits of the uppermost portion of the Paratirolites Limestone to the upper Changhsingian Boundary Clay post-extinction facies is sharp lithologically and in terms of faunal content. This change appears to be associated with shallowing but there is no evidence of erosion or subaerial exposure. Despite of the presence of microgastropod packstone and bioclastic wackestone with clotted appearance in their micritic matrix, which is indicative of microbial origin, at the beginning of Triassic at the Zal section, but no microbial buildups such as thrombolite are observable in the lowermost beds of the Elika Formation. Keratos sponge fabric, which has been previously reported only from the uppermost beds of the upper Changhsingian Paratirolites Limestone at Zal section, has been found both in uppermost Changhsingian Boundary Clay and in lowermost beds of the Lower Triassic Elika Formation as post-extinction facies. Upper Permian to Lower Triassic transition at Zal section is associated with considerable microfacies change from deep water setting to shallow water inner shelf setting. Microbial carbonates appear in the upper beds of the lower part and in the middle and upper parts of the Lower Triassic Elika Formation at Zal section and in a more limited way includes thrombolite, clotted micrite and cortoids.
کلیدواژهها [English]
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