Petrography, Mineralogy and Geochemistry of Cretaceous

Journal of Asian Earth Sciences 83 (2014) 13–34

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Journal of Asian Earth Sciences

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Petrography, mineralogy and geochemistry of Cretaceous sediment samples from western Khorat Plateau, Thailand, and considerations on their provenance ⇑ Seriwat Saminpanya a, , Jaroon Duangkrayom b, Pratueng Jintasakul b, Rattanaphorn Hanta b a Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand b Northeastern Research Institute of Petriﬁed Wood & Mineral Resources (In Honour of His Majesty the King) Nakhon Ratchasima Rajabhat University, Nakhon Ratchasima, Thailand article info abstract

Article history: At Mo Hin Khao on the western flank of Khorat Plateau, Thailand, the Phra Wihan Formation reveals Received 30 June 2013 litharenite and sublitharenite with some subarkose and arkose. A cuesta in the eroded sedimentary Received in revised form 19 December 2013 sequence exhibits spectacular rock pillars of considerable geotourist potential. The rock sequence is high Accepted 5 January 2014 in silica (SiO 67–98 wt%) and contains quartz, mica, magnetite, chert fragments and accessory minerals Available online 17 January 2014 2 such as zircon and tourmaline and amphibole species. These accessory minerals suggest felsic rocks, such as granite, granodiorite and pegmatite, were sources for the sandstones. Geochemical analyses of the sed- Keywords: imentary sequence suggest that source rocks may lie in the passive continental margin, before sediment Mineralogy transport and deposition in the Khorat Basin by rivers flowing across a large flood plain. Many deposi- Geochemistry Provenance tional sequences/episodes formed thick beds of cross bedded clastic rocks. A high average maturity index Khorat Group (>5) indicates sedimentary reworking/recycling. Chemical Index of Alteration (CIA) values range from 47 Phra Wihan Formation to 98, suggesting variable chemical weathering within the source area rocks, largely representing mod- Chemical Index of Alteration erate to high degrees of weathering. The average CIA value of these sediments (78) suggests that rela- Mo Hin Khao tively extreme alteration factors were involved. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction of an anastomosing river system within a semi-arid to sub-humid paleoclimate with wet-dry cycles (Horiuchi et al., 2012). The con- The Mo Hin Khao cuesta on the western edge of the Khorat tacts between the Phu Kradung and overlying Phra Wihan and Plateau, formed by erosion of clastic rocks of the Phra Wihan Sao Khua Formations are all gradational and conformable. The Formation, within the Mesozoic Khorat Group (Fig. 1). The site is high-frequency occurrence of Corollina (Classopollis) indicates an located within the Phulaenkha national forest in the Chaiyaphum Early Cretaceous age for the Phra Wihan Formation with a warm province, Thailand and covers an area of 0.32 km2 at an elevation climate, seasonally dry, and subtropical palaeoclimate for the of 800 m a.s.l. The dipslope (strike N–S with low-angle dip, area. The thickness is 100–250 m (Racey and Goodall, 2009; <15°E) has a steep escarpment to the west. The Phra Wihan Meesook, 2011). Although the Phu Kradung Formation is also early Formation was deposited in the early Cretaceous (Barriasian to Cretaceous, the lowest part could be Late Jurassic (Racey and Barremian, 125–145 Ma), on the basis of palynological data from Goodall, 2009); its thickness ranges from 800 m to 1200 m. The near the base of the formation (Racey et al., 1996; Racey and rocks are generally composed of maroon siltstone and claystone Goodall, 2009). These light buff to gray, fine-grained to coarse- but sandstone and conglomerate are also found (Meesook and grained quartzitic sandstones and rarer siltstone and mudstone Saengsrichan, 2011). According to Racey (2009), the Phu Kradung with occasional conglomerate were reported as deposits of braided Formation sits conformably on the Nam Phong Formation, which and meandering streams in a tropical palaeoclimate (Meesook, includes an upper member of Late Jurassic age, and a lower mem- 2000). Racey and Goodall (2009) interpreted them as deposits ber of Late Triassic age, separated by a hiatus (Racey, 2009). That within a fluvial environment dominated by high-energy, shallow hiatus is adopted by some authors as the base of the Khorat Group braided rivers with subordinate low energy meandering river sys- (e.g. Racey, 2009; Booth and Sattayarak, 2011), whereas others (e.g. tems and associated floodplains. Both the Phra Wihan and under- Meesook and Saengsrichan, 2011) place the base of the Khorat lying Phu Kradang Formations have been interpreted as deposits Group at the base of the lower Nam Phong Formation. The Phu Kradung Formation comprises red-brown micaceous sandstone, conglomerate, siltstone and mudstone of mainly fluviatile origin. ⇑ Corresponding author. Tel.: +66 26495000x18668; fax: +66 26495628. E-mail address: [email protected] (S. Saminpanya).

101o15’0’’E750000 800000 850000 102o30’0’’E 1850000 1850000 Khon San Phu Wiang Ksk PTRv JKpk TrJnp Trhl Ps TrJnp Trhl Trhl Nong Ruea

JKpk Kpw Phrom river TrJnp Qa Phu Khiao Ps Kpw JKpk PTRv 15’0’’N o

15’0’’N Kaset Sombun TrJnp o 16 1800000 1800000 16

Trhl JKpk Kaeng Khro Nong Bua Daeng Ban Non Toom Mo Hin Khao TrJnp Trhl Pha Hua Nak JKpk Chi river Kpw

Chaiyaphum Phon 1750000 Ksk 1750000 Ban Khwao Qa Wichian Buri 100o 105o CHINA 110 o Kkk MYANMAR LAOS GULF 20o Kpp Bua Yai OF Chatturat TONKING

THAILAND SOUTH CHINA Bamnet Narong SEA Kms STUDY AREA 15o Bangkok

Khong M CAMBODIA A N T -10 0 10 E I V Thep Sathit GULF Km. OF 10o THAILAND N 1700000 1700000 0 200 km 5o

o o 101 15’0’’E750000 800000 850000 102 30’0’’E AGE Qa Alluvial sediments of gravel, sand, silt and clay deposited along river banks and flood basins Quaternary AGE Purple and maroon siltstone with calcareous texture Jurassic-Cretaceous Reddish brown, red siltstones; Claystone and JKpk and micas, Green and yellow brown sandstones, Kms sandstone with rocksalt, gypsum and andydrite Conglomerate with calcrete Reddish brown sandstone with bivalves, Conglomerate Calcareous reddish brown and red siltstone and TrJnp with particlas of quartz, quartzite, chert, igneous rocks; Triassic-Jurassic Kkk sandstone; Claystone and Conglomerate with calcrete Siltstone, Mudstone, and Limestone lens

Grey and greenish grey and brown sandstones with Basal conglomerate, Volcanic aggromerate, Shale, Kpp granules, thick cross bedding; Siltstone and Sandstone Cretaceous Trhl Mudstone, Siltstone colored gray, yellow brown; Triassic with gravels of quartz, chert, jasper and igneous rocks Greywacke, Argillaceous limestone and Marl with leaf Rhyolite, Andesite, Tuff, Volcanic breccia, Rhyolitic tuff Siltstone and Sandstone of reddish brown, maroon and PTR Permo-Triassic Ksk red colours with calcrete and silcrete v and andesitic tuff White pink or grey quartz-sandstone with large scale Fossiliferous limestone, Chert, Pillow lava basalt, cross bedding and thick beds, interbedded with Kpw Ps Ultrabasic and Serpentinite Permian conglomeratic sandstone, some areas interbedded with thin layers of mudstone or red siltstone NW Sketch of cross section SE (not to scale) Nong Bua Daeng Ban Non Toom Mo Hin Khao Lam Pa Thao Dam Kaeng Khro Phu Khiao Phu Pha Kham

Kpw Kpw JKpk Kpp JKpk Kpw JKpk Ksk TrJnpTrJnp

(Lertsirivorakul, et al. 2006)

Fig. 1. Location and geological maps of Chaiyaphum province. (Rock boundaries are from Department of Mineral Resources (2007).) (See above-mentioned reference for further information.) Download English Version: https://daneshyari.com/en/article/4730785

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