Detrital record of Indosinian mountain building in SW China: Provenance of the Middle Triassic turbidites in the Youjiang Basin

2012 ◽  
Vol 574-575 ◽  
pp. 105-117 ◽  
Author(s):  
Jianghai Yang ◽  
Peter A. Cawood ◽  
Yuansheng Du ◽  
Hu Huang ◽  
Lisha Hu
Keyword(s):  
Middle Triassic ◽  
Mountain Building ◽  
Sw China ◽  
Youjiang Basin

scholarly journals Exceptional appendage and soft-tissue preservation in a Middle Triassic horseshoe crab from SW China

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Shixue Hu ◽  
Qiyue Zhang ◽  
Rodney M. Feldmann ◽  
Michael J. Benton ◽  
Carrie E. Schweitzer ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Horseshoe Crab ◽  
Middle Triassic ◽  
Tissue Preservation ◽  
Sw China ◽  
Soft Tissue Preservation

New mixosaurid ichthyosaur specimen from the Middle Triassic of SW China: further evidence for the diapsid origin of ichthyosaurs

2011 ◽  
Vol 85 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Jun Liu ◽  
Jonathan C. Aitchison ◽  
Yuan-Yuan Sun ◽  
Qi-Yue Zhang ◽  
Chang-Yong Zhou ◽  
...  
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Middle Triassic ◽  
Evolutionary Stage ◽  
Temporal Region ◽  
Sw China ◽  
Anterior Process ◽  
Cladistic Analyses

Recent cladistic analyses have all suggested a diapsid origin of ichthyosaurs. However, an intermediate evolutionary stage of the lower temporal region of ichthyosaurian skull between basal diapsids and derived ichthyosaurs has been absent from the fossil record. Here we describe the cranial skeleton of a new mixosaurid ichthyosaur specimen with a well-preserved lower temporal region from the Anisian Guanling Formation of eastern Yunnan. It is characterized by the most primitive lower temporal region within known ichthyosaurs. The primitive characters of the lower temporal region include both external and internal separation between the jugal and the quadratojugal, an anterior process of the quadratojugal, an apparent posteroventral process of the jugal, and a large lower temporal opening surrounded by the jugal, the postorbital, the squamosal, and the quadratojugal. The lower temporal region of this specimen provides the most direct evidence to the diapsid origin of ichthyosaurs. It also suggests that the disappearance of the lower temporal fenestra is caused initially by the reduction of the lower temporal arcade rather than the enlargement of the surrounding bones.

scholarly journals A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Jun Liu ◽  
Shi-xue Hu ◽  
Olivier Rieppel ◽  
Da-yong Jiang ◽  
Michael J. Benton ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Sw China ◽  
Biotic Recovery

scholarly journals Tennantite–Tetrahedrite-Series Minerals and Related Pyrite in the Nibao Carlin-Type Gold Deposit, Guizhou, SW China

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 2
Author(s):  
Dongtian Wei ◽  
Yong Xia ◽  
Jeffrey A. Steadman ◽  
Zhuojun Xie ◽  
Xijun Liu ◽  
...  
Keyword(s):  
Mineral Assemblage ◽  
Gold Deposits ◽  
Appreciable Amount ◽  
Gold Ores ◽  
Sw China ◽  
Sem Image ◽  
Clastic Rocks ◽  
The Core ◽  
Metal Contents ◽  
Youjiang Basin

A number of sediment-hosted, Carlin-type/-like gold deposits are distributed in the Youjiang basin of SW China. The gold ores are characterized by high As, Hg, and Sb contents but with low base metal contents (Cu+Pb+Zn < 500–1000 ppm). The Nibao deposit is unique among these gold deposits by having tennantite–tetrahedrite-series minerals in its ores. The deposit is also unique in being primarily hosted in the relatively unreactive siliceous pyroclastic rocks, unlike classic Carlin-type gold deposits that are hosted in carbonates or calcareous clastic rocks. In this study, we have identified tennantite-(Zn), tennantite-(Hg), and tetrahedrite-(Zn) from the tennantite–tetrahedrite-series mineral assemblage. The tennantite-(Zn) can be further divided into two sub-types of Tn-(Zn)-I; and Tn-(Zn)-II;. Tn-(Zn)-I; usually occurs in the core of a Tennantite–tetrahedrite composite and appears the darkest under the SEM image, whereas Tn-(Zn)-II overgrows on Tn-(Zn)-I and is overgrown by tetrahedrite-(Zn). Tennantite-(Hg) occasionally occurs as inclusions near the uneven boundary between Tn-(Zn)-I and Tn-(Zn)-II. An appreciable amount of Au (up to 3540 ppm) resides in the tennantite–tetrahedrite-series minerals, indicating that the latter is a major Au host at Nibao. The coexistence of tennantite–tetrahedrite-series minerals and Au-bearing pyrite indicates the Nibao ore fluids were more oxidized than the Carlin-type ore fluids. The tennantite–tetrahedrite series at Nibao evolved from Tn-(Zn)-I through Tn-(Zn)-II to tetrahedrite-(Zn), which is likely caused by Sb accumulation in the ore fluids. This indicates that the Nibao ore fluids may have become more reduced and less acidic during Au precipitation.

scholarly journals Supplemental Material: The assembly of the South China and Indochina blocks: Constraints from the Triassic felsic volcanics in the Youjiang Basin

2020 ◽  
Author(s):  
Chengshi Gan ◽  
Yuzhi Zhang ◽  
et al.
Keyword(s):  
South China ◽  
Middle Triassic ◽  
Volcanic Rocks ◽  
Icp Ms ◽  
O Isotopes ◽  
Youjiang Basin ◽  
Felsic Volcanic ◽  
Early Middle Triassic ◽  
Felsic Volcanic Rocks

Table S1: LA-ICP-MS zircon U-Pb dating results for Early-Middle Triassic felsic volcanic rocks in the Youjiang Basin; Table S2: In-situ zircon Hf-O isotopes results for Early-Middle Triassic felsic volcanic rocks in the Youjiang Basin; Table S3: Geochemical compositions for Early-Middle Triassic felsic volcanic rocks in the Youjiang Basin.

scholarly journals Early Jurassic Mafic Intrusions in the Southern Youjiang Basin, SW China: Petrogenesis, Tectonic and Metallogenic Implications

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 771 ◽  
Author(s):  
Wen Jiang ◽  
Quanren Yan ◽  
Li Deng ◽  
Bin Zhou ◽  
Zhongjin Xiang ◽  
...  
Keyword(s):  
Gold Mineralization ◽  
Tectonic Setting ◽  
Element Distribution ◽  
Early Jurassic ◽  
Trace Element Distribution ◽  
Sw China ◽  
Mafic Intrusions ◽  
Isotopic Analyses ◽  
Youjiang Basin ◽  
Back Arc

A suite of mafic intrusions, composed of diabase and micro-gabbro outcrops in the Jingxi area of southern Youjiang Basin, SW China. This study conducts geochronological, geochemical, and Sr–Nd isotopic analyses on the mafic intrusions in Jingxi with the aim of determining their petrogenesis, tectonic setting, and metallogenic implications. Zircon U–Pb dating for the mafic intrusions yielded an age of 183 ± 3 Ma (MSWD = 2.3), which is coeval with the Carlin-like gold mineralization in the Youjiang Basin. The mafic intrusions are alkaline in composition and characterized by low TiO2 (1.25–1.87 wt %) contents and low Ti/Y ratios (410–550). They exhibit OIB-like patterns of trace element distribution and they have low (87Sr/86Sr)i ratios of 0.704341 to 0.705677, slightly negative εNd(t) values of −0.30 to −2.16, low La/Ta (11.57–15.66) and La/Nb (0.77–1.06) ratios, with [La/Yb]N = 6.52–10.63. The geochemical characteristics, combined with regional considerations, suggest that the mafic intrusions originated from partial melting of upwelling asthenosphere within the garnet-spinel transition zone, as a result of intracontinental back-arc extension triggered by the steep subduction of the Paleo-Pacific plate beneath the South China Block. Moreover, the new data not only suggest Early Jurassic magma was a possible heat source, but also support a magmatism-related model for the Carlin-like gold mineralization in the Youjiang Basin.

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