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We discuss traces from the ichnospecies Undichna unisulca recorded from the Triassic that are reported for the first time in this paper. These fossils are also some of the oldest vertebrate ichnites discovered in China to date. The fish swimming traces ( Undichna unisulca) described originate from the Lower Triassic. These traces were found in the Jialingjiang Formation and are located at a gorge ∼7.5 km from Emei, Sichuan Province, China. The ichnospecies Undichna unisulca consists of a regular sinusoidal wave. The wavelengths and amplitudes are quite constant between each specimen ranging between 28-32 mm and 9-12 mm, respectively. The fish swimming traces and distribution within the same bed are preserved as hypichnial ridges at the undersurface. [ABSTRACT FROM AUTHOR]

The Ginglymodi are a group of ray-finned fishes that make up one of three major subdivisions of the infraclass Neopterygii. Extant ginglymodians are represented by gars, which inhabit freshwater environments of North and Central America and Cuba. Here, we report the discovery of well-preserved fossils of a new ginglymodian, Kyphosichthys grandei gen. et sp. nov., from the Middle Triassic (Anisian) marine deposits (Guanling Formation) in Luoping, eastern Yunnan Province, China. The discovery documents the first known fossil record of highly deep-bodied ginglymodians, adding new information on the early morphological diversity of this group. The studies of functional morphology of extant deep-bodied fishes indicate that Kyphosichthys is not a fast swimmer but has a good performance in precise maneuvering, representing a morphological adaptation to structurally complex habitats (e.g. thick macrophyte beds, rocky areas, or coral reefs), which differs from the other members of this group. A cladistic analysis with the new fish taxon included supports the hypothesis that the Ginglymodi are more closely related to the Halecomorphi than to the Teleostei. Represented by Felberia, Kyphosichthys, and Dapedium, a highly deep and short fish body type has independently evolved at least three times in the stem-group neopterygians, ginglymodians, and basal teleosts within the lower neopterygians of the Triassic. [ABSTRACT FROM AUTHOR]

The seismic profiles processed by high-resolution display that a blind growth fault-bend fold emerges in depth of seismic exploration area in Dayi in the southern section of the frontier Longmen Mt. This paper presents a detailed structural interpretation to seismic section, then describes the deformed geometry related to the pre-growth strata, the growth strata and the post-growth strata on both limbs of the fold. The computer geometric simulation, based on the model of fault-bend fold, is utilized to stimulate the geometry of the blind growth fold at different sedimentation rates in Dayi. These structural features are subsequently extracted and compared with the actual seismic reflection section. Our research suggests that a low angle overthrust formed during Late Triassic also appears in the southern section of the frontier Longmen Mt. The event of structure took place at the depositional stage of a portion of the middle and upper fourth member of Xujiahe Formation (T3x4), which corresponds to thrusting in the northern section of the frontier Longmen Mt. However, the thrusting displacement here is smaller than one of the northern section. [ABSTRACT FROM AUTHOR]

A Triassic oil sample from LN14 of Tarim Basin was pyrolyzed using the sealed gold tubes at 200–620°C under a constant pressure of 50 MPa. The gaseous and residual soluble hydrocarbons were analyzed. The results show that the cracking of oil to gas can be divided into two distinct stages: the primary generation of total C1–5 gases from liquid oil characterized by the dominance of C2–5 hydrocarbons and the secondary or further cracking of C2–5 gases to methane and carbon-rich matters leading to the progressive dryness of gases. Based on the experimental data, the kinetic parameters were determined for the primary generation and secondary cracking of oil cracking gases and extrapolated to geological conditions to predict the thermal stability and cracking extent of crude oil. Finally, an evolution model for the thermal destruction of crude oil was proposed and its implications to the migration and accumulation of oil cracking gases were discussed. [ABSTRACT FROM AUTHOR]

Changes in the distribution of isoprenoid hydrocarbons and in δ13Ckero or δ13CPr across the section from the Changxing Formation to the lower Yinkeng Formation at Meishan (the GSSP of PTB) are studied, in which a relative enrichment of pristane and a sharp shift in both δ13Ckero and δ13Cmole near the boundary are revealed. A possible mechanism for the abnormal accumulation of pristane near PTB is suggested: Lipids in some marine animals and their metabolites, rich in pristane, can be preserved and accumulate in some suitable depositing facies under certain special conditions, such as the catastrophic death of animals and/or developing of an anoxic water column, and thus the pristane enrichment occurs in the sediment. The occurrences of isoprenoid enrichment and high Pr/Ph ratios have been found in other typical marine anoxic sediments accompanied by mass extinction in various extent during the most important geological periods, such as Late Ordovician, end of Devonian, Early Jurassic and Late Cretaceous. These occurrences support to a certain extent the above mechanism that interprets the genesis of a high Pr/Ph ratio in some typical marine anoxic sediments. The synchronous sharp negative shifts in δ13Cmole, δ13Ckero and δ13Ccarb from Beds 24 to 26 of the Meishan profile indicate that a sudden and strong variation of carbon source in the atmosphere-ocean system occurred during the quick but equable evolution from the end-Permian to Early Triassic, and the coupling between the pristane enrichment and negative shift in δ13Ckero and δ13CPr may well indicate the importance of the release of methane hydrates and marine anoxia in the end-Permian mass extinction. [ABSTRACT FROM AUTHOR]

A new method for the quantitative assessment of hydrocarbon generation potential from coals by means of the chemical reaction kinetics has been developed gradually over the recent years. In this paper, the kinetic parameters of hydrocarbon gas generation are determined by high temperature and pressure, and closed- system thermal simulation for Late Paleozoic coals in the Qinshui Basin and the kinetic characteristics and the histories of hydrocarbon gas generation were studied using the parameters obtained. Results show that during the longer period from the Triassic (T) to the Middle Jurassic (J2), the coal-derived methane yield increased more slowly under lower palaeogeotemperature in the Qinshui Basin; however, the shorter period from Late Jurassic to Early Cretaceous, the coal-derived methane yield increased more rapidly under higher palaeogeotemperature. The correlation between the thermal simulation and the factual data shows that C1/(C1+C2-4) coefficients computed by the histories of methane and C2-C4 hydrocarbon generation can provide evidence for the identification of the genesis of coal bed gas in the different areas of the Qinshui Basin. The kinetic simulating experiment of hydrocarbon generation for the peat considered as the original matter of coal formation was performed for the first time and the simulated results were compared with the characteristics of hydrocarbon generation from coals undergoing various palaeogeotemperature in the Qinshui Basin. The result indicates that the peat has a higher potential of hydrocarbon generation than that of coals. Therefore, the hydrocarbon generation results obtained from kinetic simulation for coal with higher maturation rank could not stand for their original hydrocarbon generation potential and thus would lead to an underestimation for coal-bed gas resource. The generative amount of coal-derived gas in the Qinshui Basin was predicted using kinetic simulation results for the peat and their maximum was estimated. The calculation shows that the generative amount of coal-derived gas from Taiyuan Formation and Shanxi Formation coal-beds in the Qinshui Basin is the highest in Yangcheng area, higher in Qinyuan area and the lowest in Huoshan area. Therefore, the conditions of coal-bed gas generation are the best in Yangcheng area, the second in Qinyuan area and not very good in Huoshan area. [ABSTRACT FROM AUTHOR]

Various shaped mafic microgranular enclaves (MMEs) together with several mafic massifs are developed within the Yuegelu granitoid pluton in the eastern part of the Eastern Kunlun. On the basis of detailed field geological surveying and of the results of the petrological and geochemical studies it is suggested that there must be some genetic relationship among the granodiorite host, the MMEs and the hornblende (Hb)-gabbro massifs. Magmatic zircon grains are extracted from samples of granodiorite host rock, Hb-gabbro and the MMEs for U-Pb dating. The U-Pb ages are determined by using SHRIMP II technique, which yields the ages of 242±6 Ma, 239±6 Ma and 241±5 Ma, respectively. The overall correspondence in the U-Pb dating results of them excludes the possibility that the MMEs in the granitoids are solid refractory relics from the source region or that they are xenoliths from the wall rocks. It can also rule out the possibility of a later emplacement of basic magma after the solidification of the granitoids. This dating result indicates that they are the products of magma mixing in early-mid Triassic epoch. Among them the granitoid host is chemically akin to the acidic end member during the magma mixing process, the Hb-gabbro is akin to the basic ones while the MMEs are the incompletely mixed basic magma clots trapped in the acidic magma. Combined with the results from other researches on this pluton it is reasonable to consider that in the mid-Triassic the Eastern Kunlun granitoid belt had undergone a process of magma mixing between the mantle-derived basic magma and the crustal acidic magma which indicates that the injection of mantle materials and energy into the crust and the reactions between them played an important role in the formation of the granitoid rocks. [ABSTRACT FROM AUTHOR]

Discusses the emplacement timing of granitic plutons at Chaxinzi, Xiaoweishahe and Longfou in the Tonghua area, south of Jilin Province. The results of single-grain zircon U-Pb dating, which show these plutons formed in the Triassic period with ages of 203–217 Ma; Geological and geochemical characteristics of the plutons, which consist of quartz diorite and granite; Evidence of partial melting in the mafic lower crust and thickened crust with garnet as the residue in the source; How the protoliths are different despite having the same emplacement age; Indication that these plutons are petrologically different from the coeval granites in the Xingmeng (Xing’an–Mongolian) to Jihei (Jilin–Heilongjiang) orogenic belt in the north; Suggestion that their formation was related to theDabie–Sule ultrahigh-pressure collisional orogenesis; Association with the first rapid exhumation of the ultrahigh-pressure metamorphic rocks and emplacement of the post-collisional granites.

Deals with a study which provided a geochronological evidence that there are Triassic granites in the Dabie mountains. Samples and analytical methods; Results; Geological implication.

Presents information on study which examined the paleomagnetism of early Triassic Daye formation from Hubei Province and its tectonic implications. Methodology; Results; Discussion.

Discusses the advances in the study of the Lower Triassic conodonts at Meishan Section, Changxing, Zhejiang Province in China. Meishan as the best selection of global stratotype section and point (GSSP) of the Permian and Triassic boundary (PTB); Advantage of Zhejiang Province in competing for the GSSP of PTB.

Studies the Upper Triassic coal-bearing strata in the Liupanshan Basin, Ningxia Hui Autonomous Region in China. Stratigraphy; Geological age; Significance to the oil-gas exploration of the basin and the interpretation of the sedimentary and tectonic history of the area during the early Mesozoic era.

Investigates the Permian and Triassic strata by the working group for continental Permian and Triassic sequences from the Institute of Geology, Ministry of Geology and Mineral Resources, Gansu Institute of Geology and Mineral Resources, under Gansu Bureau of Geology and Mineral Resources, in 1981. Years in which excavation was carried out; Findings of the investigation; Indepth look at the investigation.