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Abstract

ABSTRACT:The Permain Nam Duk Basin is a part of the Phetchabun Fold Belt of central mainland Thailand. This basin is considered to be a geological backbone of tectonic evolution during the Late Paleozoic in Thailand. In this study, provenance analysis of the siliciclastic sediments of the Nam Duk Formation has been carried out based on geochemical and cathodoluminescence techniques. The geochemical result indicates that the siliciclastic sediment of Lower-Middle Permian "pelagic sequence" is a transitional deposit between an oceanic island arc and a continental island arc environments and is derived mainly from metabasic sources. During middle Middle to late Middle Permian, the provenance signatures of sandstones and shales from the "flysch" and the "molasse" sequences show indications of ultramafic-mafic igneous provenance and they were deposited in a continental island arc environment. The result supports the interpretation of NanUttaradit ophiolitic belt north-west of the Nam Duk Basin as a major terrane which supplied siliciclastic sediments to the Nam Duk Basin during Middle-Late Permian.

Geology and petrochemistry of volcanic rocks in the Lam Sonthi area, Lop Buri province

“…The Khao Luak Formation age is recently reported as 276±7 Ma (Early Permian) from the detrital zircons using the U-Pb zircon age dating technique of sandstones, which was collected from Nong Phai district, Phetchabun province (Hara et al, 2020) far north from the Lam Sonthi area. The Khao Luak Formation was interpreted as formed as the southern continuation of Nam Duk Formation (Ueno and Charoentitirat, 2011) which was a part of back arc basin that has been closed in the end of Permian (Malila et al, 2008;Sone and Metcalfe, 2008). This closure of the Nam Duk basin is believed to have taken place during the Indonesian orogeny I, which caused the hiatus in the Late Permian and Middle Early Triassic (Booth and Sattayarak, 2011).…”