Geochemical characteristics of the oceanic island-type volcanic rocks in the Chiang Mai zone,northern Thailand

The oceanic island volcanic rocks in the Chiang Mai zone, northern Thailand, are usually covered by Lower Carboniferous and Upper Permian shallow-water carbonate rocks, with the Hawaii rocks and potash trachybasalt being the main rock types. The alkaline series is dominant with sub-alkaline series occurring in few cases. The geochemical characteristics are described as follows: the major chemical compositions are characterized by high TiO₂, high P₂O₅ and medium K₂O; the rare-earth elements are characterized by right-inclined strong LREE-enrichment patterns; the trace element patterns are of the upward-bulging K-Ti enrichment type; multi-component plots falling within the fields of oceanic island basalts and alkali basalts, belonging to the oceanic island-type volcanic rocks, which are similar to the equivalents in Deqin and Gengma (the Changning-Menglian zone) of Yunnan Province, China.     

Zircon U–Pb geochronology,and elemental and Sr–Nd–Hf–O isotopic geochemistry of post-collisional rhyolite in the Chiang Khong area,NW Thailand and implications for the melting of juvenile crust

International Journal of Earth Sciences - Volcanic rocks are widely exposed within the Chiang Khong–Lampang–Tak igneous zone in NW Thailand. A representative rhyolite sample from the...     

Correlation of Triassic stratigraphy between the Simao and Lampang-Phrae Basins: implications for the tectonopaleogeography of Southeast Asia

Based on our extensive fieldwork in southwestern Yunnan and northern Thailand, followed by detailed stratigraphic and paleontological studies, we propose that the Triassic Simao Basin in Yunnan can be correlated with the Triassic Lampang–Phrae Basin in Thailand. Strata equivalent to those in the southern Lancangjiang sub-basin have not been identified in northern Thailand. We consider that during the Triassic the Simao and the Lampang–Phrae Basins belonged to the same tectonopaleogeographic unit. The orogenic belt to the east of this unit includes the Nan–Uttaradit and Ailaoshan sutures. The ‘Shan–Thai Block’ in northern Thailand, can be divided from east to west into the Sukhothai, the Inthanon, and the Shan terranes. According to tectonopaleogeographic correlation, our results support the idea that the Sukhothai Terrane, including the Lampang–Phrae Basin, belongs to the Cathaysian domain and not to Gondwana domain, and that the geosuture corresponding to the Changning–Menglian Suture in Yunnan must lie to the west of the Sukhothai Terrane in Thailand.     

泰国清莱地区三叠纪南邦群碎屑锆石LA-ICP-MS U-Pb年龄及其地质意义

对于中国滇西和东南亚地区古特提斯缝合带对比一直存在诸多争议。在泰国清莱地区三叠纪南邦群中采集4件碎屑岩样品,进行岩石学、地球化学和锆石U-Pb测年研究。岩石学和地球化学研究表明,该套碎屑岩的源岩主要为基性—中基性岩石,卷入少量长英质岩石,物源区大地构造背景为岛弧带。所测得最古老锆石U-Pb同位素年龄为3269Ma±29Ma,绝大多数年龄集中形成3个峰值：280~250Ma、500~440Ma和1200~1100Ma,指示清莱地区三叠纪南邦群碎屑物源区主要为清莱岛弧火山岩带西部条带和前泥盆纪变质岩系。碎屑锆石年龄图谱的对比结果表明,原特提斯构造阶段之前,南邦地体与西澳大利亚发育类似构造—热事件;在原特提斯构造阶段之后,其构造—热事件特征与扬子构造域相类似,指示古特提斯洋的主洋盆应该在南邦地体以西,支持清迈构造带代表古特提斯主洋盆的观点。     

Long-lived Paleotethyan pelagic remnant inside Shan-Thai Block: Evidence from radiolarian biostratigraphy

The Shan-Thai Block, regarded traditionally as awhole geotectonic unit by the geologists engaged inthe study of geotectonic evolution of Southeast Asia, issituated to the west of the Ailaoshan and Nan-UttaraditSutures and to the east of the Shan Boundary Faults,and covers southwestern Yunnan, eastern Myanmar,most of Thailand, northwestern Laos, western Malay-sia, and Sumatra[1,2] (fig. 1). However, recent researchshows that it consists of two continental terranes fromGondwana and Cathay…     

泰国北部难河构造带二叠纪放射虫、硅质岩和玄武岩

在泰国北部难河构造带Pha Som变质杂岩中发现保存很好的放射虫硅质岩、玄武岩地层层序.层状硅质岩含放射虫化石Follicucullus porrectus, 地质时代为中二叠世晚期至晚二叠世早期.其硅质岩SiO₂含量均在92.5%以上, Al/ (Al+Fe+Mn) 平均比值为0.51, Ce/Ce*比值为1.14, 为大陆边缘型硅质岩.玄武岩具有富集大离子亲石元素与高场强元素以及轻稀土富集等洋岛玄武岩的特点.说明难河构造带中-晚二叠世之交存在洋岛型火山岩和靠近大陆边缘的深海盆地硅质岩, 代表了小洋盆的沉积组合.该构造带闭合时间应在晚二叠世与晚三叠世之间.