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A remarkable end-Permian boulder bed of conglomeratic at Nam Nao in NE Thailand: its biostratigraphical and environmental significance limestone |
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| รหัสดีโอไอ | |
| Creator | Shigeki Hada |
| Title | A remarkable end-Permian boulder bed of conglomeratic at Nam Nao in NE Thailand: its biostratigraphical and environmental significance limestone |
| Contributor | Somboon Khosithanont, Hiroya Goto |
| Publisher | Department of Mineral Resources of Thailand |
| Publication Year | 2563 |
| Journal Title | Thai Geoscience Journal |
| Journal Vol. | 1 |
| Journal No. | 1 |
| Page no. | 1-17 |
| Keyword | foraminifer species, boulder bed of limestone, sea level drop, Upper Permian, Indochina Block |
| URL Website | http://www.dmr.go.th/index_.php, https://tgjdmr2019.wixsite.com/mysite, https://tgjdmr2019.wixsite.com/mysite/download-article |
| Website title | กรมทรัพยากรธรณี, THAI GEOSCIENCE JOURNAL |
| Abstract | Litho- and bio-stratigraphic analyses on the Lower Permian Khao Pa Khi and Middle-Upper Permian Khao Tham Yai limestones, and the siliciclastic Hua Na Kham Formation on clastic-dominant continental shelves in the western margin of the Indochina Block record important aspects of the extinction-related Guadalupian-Lopingian (G-LB) interval, and a large-scale sea-level drop of a global environmental change in the low-latitudes of the East Paleo-Tethys. Fusulinid and foraminifer species within the Khao Tham Yai Limestone record the abrupt disappearance of large-tested fusulines. The Khao Tham Yai Limestone above the G-LB is characterized by the sudden flourishing of a diverse range of smaller fusulinid and foraminifer species, together with the occurrence of a large number of broken fragments of diverse large-tested fusulinids. The second disappearance of smaller foraminifers occurred during the Wuchiapingian in the upper part of the Khao Tham Yai Limestone. These two phases of disappearance of fusulinid and foraminifer species on the continental margin of the Indochina Block likely appeared a little late compared to similar phases in the paleo-atolls of the mid-Panthalassa. The Wuchiapingian Hua Na Kham Formation unconformably onlaps the Khao Tham Yai Limestone replacing previous carbonate formation. These carbonate and siliciclastic formations are largely heteropic facies and possibly interfinger with each other. A remarkable boulder bed of fusulinids and conglomeratic limestones occurs on the top of the Hua Na Kham Formation. Fusulinid and foraminifer species in boulders indicate that they were eroded off the Khao Tham Yai barrier reef and transported by submarine debris flows that brought them to sites on the continental shelf where the Hua Na Kham Formation deposited. Such catastrophic events may have been caused by large-scale eustatic sea-level drop. The effects of this global environmental change on the continental margin of the Indochina Block may have occurred a little later in the Wuchiapingian compared with subaerial exposure and erosion reported from the G-LB interval in mid-oceanic seamounts that occur in mid-Panthalassa. |
