کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4466060 | 1622170 | 2015 | 12 صفحه PDF | دانلود رایگان |
• Oncoids/microbialites were abundant on a Panthalassan atoll in the Artinskian.
• The microbial community flourished exclusively in a subtidal environment.
• The microbial community represents transitional members during a biotic shift.
• The biotic shift resulted from climate change related to Gondwanan deglaciation.
Large oncoids (up to 14 cm) and microbialites are abundant in the Artinskian (Lower Permian) section of mid-Panthalassan Akiyoshi atoll carbonates. The oncoids and microbialites consist mainly of a tubular microproblematicum, girvanellid cyanobacterial filaments, microbial micrite crusts, and pore-filling sparry calcite cements. They are surrounded by intraclastic–bioclastic grainstone/rudstone, indicative of moderate- to slightly high-energy subtidal conditions. The microbial community was the primary boundstone-forming organisms on the Akiyoshi atoll during this time. It represents a transitional stage in a mid-Panthalassan reef succession between a cooler-water autotrophic Palaeoaplysina–microencruster community in the Gzhelian–Asselian and a warmer-water heterotrophic calcareous sponge–microencruster community in the Middle Permian. The flourishing mid-Panthalassan microbial community during the late Early Permian is related to enhanced alkalinity, increasing nutrient levels, elevated sea-surface temperatures, and the absence of major reef-building metazoans, which resulted from Gondwanan deglaciation, climatic changes, and a pulse of active volcanism.
Journal: Palaeogeography, Palaeoclimatology, Palaeoecology - Volume 420, 15 February 2015, Pages 116–127