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The northeastern Sichuan area in the northern Yangtze margin has unique Ediacaran geological records, especially the Doushantuo Formation (DST), and become a hot research area in recent years. However, the Cryogenian-Ediacaran (C-E) boundary has not been precisely identified, which restricts the in-depth study of geological information during this crucial transitional period and is unfavorable for a systematic and complete understanding of the Yangtze Block and even the global paleogeographic pattern. This study conducted stratigraphy, sedimentology, and chronostratigraphy to establish the stratigraphic framework and sedimentary evolution of the C-E transition strata in northeastern Sichuan. The results showed that the Ediacaran sediments, without the cap dolomite, unconformably overlaid the Cryogenian sediments in the studied area. The Member II of the DST, characterized by 50e160 m of red-green sandstone (approximately equivalent to the original Chengkou "Guanyinya Formation"), directly overlaid the Cryogenian sediments and displayed a 623 ± 2.3 Ma maximum depositional age from the detrital zircon UePb dating. Regional stratigraphic correlations indicate that the C-E transition strata in northeastern Sichuan had a consistent lithological association and sedimentary sequence characteristics but differed from the Three Gorges. Typically, the upper Nantuo massive glacial diamictites transition to the icebergs rafted lonestone-bearing mudstones at the top, then change upward to DST barrier coast sandstones. The proposed DST of the northeastern Sichuan Basin was divided into three lithostratigraphic members without the regional Member I cap dolomite: (i) Member II purple-red, gray-green sandstone strata, (ii) Member III black mudstone strata, and (iii) Member IV P-Mn bearing strata. During the C-E transition, the study area experienced (i) the global deglaciation stage in the terminal Marinoan glaciation and (ii) the filling-leveling up stage with clastic rocks in the early Ediacaran. Overall, the early Ediacaran of northeastern Sichuan succeeded the paleogeographic features of the late Cryogenian. [ABSTRACT FROM AUTHOR]

Thrixspermum taeniophyllum is described as a new orchid species from Wenchuan County, Sichuan Province of southwest China. It is morphologically similar to T. japonicum, but it differs from the latter in having branched stems, slightly fleshy strapshaped leaves, longer inflorescences with 3–6 flowers and a capitate gynandrium with a lip-shaped mouth opening. Its species status is also supported by molecular phylogenetic analyses, based on nuclear ribosome internal transcribed spacer (nrITS) and three chloroplast DNA fragments (matK, psbA-trnH and trnL-F), which showed distinct systematic boundaries from the most morphologically similar T. japonicum and their morphological relatives T. saruwatarii and T. pygmaeum. [ABSTRACT FROM AUTHOR]

Gastrochilus heminii (Orchidaceae), a new orchid species from Sichuan Province, Southwest China, is described and illustrated. It morphologically resembles G. affinis and G. yei, but differs markedly from the former in having a thinner and slightly rolled downwards reniform epichile and the central thickened purple-red mat with irregular folds (vs. subtriangular epichile curves upwards, with 2 thick, brown to purplish- brown median ridges from base to apex), and can be clearly distinguished from the latter by having reniform epichile with lobed apex and subconical hypochile with bilobed apex that splits into two conical protrusions (vs. semi-rounded epichile not lobed and subconical hypochile not bilobed). The results of molecular phylogenetic analysis based on nuclear ribosome internal transcribed spacer (nrITS) and four chloroplast DNA fragments (matK, psbA-trnH, psbM-trnD, and trnL-F) of 36 Gastrochilus species showed that G. heminii was closely related to G. affinis and G. distichus. [ABSTRACT FROM AUTHOR]

Gas field water is the formation water produced together with natural gas in the process of natural gas exploitation. The gas field water treated is difficult to reach the standard due to its wide sources, numerous types and complex composition. In addition, it can pollute soil, surface water and groundwater. In this study, the quality and pollution characteristics of gas field water in eastern Sichuan were studied by conventional water quality determination and GC-MS. The results show that the main components of gas field water in eastern Sichuan were chloride, CODcr, SS, anionic surfactant, sulfide and other substances. The gas field water could be divided into two types according to the characteristics of water quality, of which one had high mineralization and high organic compounds, and the other had high sulfur and high organic compounds. There were 17 kinds of organic pollutants in the gas field water, mainly including alkanes, alcohols, esters and a small amount of acids. [ABSTRACT FROM AUTHOR]

The role of upper-crustal faulting in building and maintaining the extreme relief of the Longmen Shan region at the eastern margin of the Tibetan Plateau has been strongly debated. The MW 7.9 Wenchuan earthquake of 12 May 2008 ruptured three distinct faults along the plateau margin and thus provides a unique insight into the mechanisms and kinematics of regional crustal deformation. Two of the faults, the northeast-striking Beichuan and Pengguan faults, had been previously recognized as active, with past surface-rupturing earthquakes in the latest Pleistocene to Holocene time. Some of the late Quaternary fault segments were activated in the Wenchuan earthquake, but others, including several with clear evidence of Holocene strike-slip displacement, were not. Instead, in almost all cases, the Wenchuan surface rupture followed geological faults mapped on the basis of bedrock lithology. We infer that active deformation along the plateau margin is accommodated by partial reactivation of a complex network of preexisting faults but that a single through-going structure has not been established--and may never be if the total deformation is strongly rotational and three-dimensional. The earthquake also illustrates that the Beichuan and Pengguan faults are kinematically linked, in part by the northwest-striking Xiaoyudong fault, and that both must be strongly listric in the upper few km of the crust. The complexity of the active (or potentially active) fault network in the Longmen Shan, coupled with rapid postearthquake modification of the surface rupture trace, poses serious difficulties for seismic hazard assessment across the region. [ABSTRACT FROM AUTHOR]

Purpose: To develop an effective method for evaluating the quality of Cortex berberidis from different geographical origins. Methods: A simple, precise and accurate high performance liquid chromatography (HPLC) method was first developed for simultaneous quantification of four active alkaloids (magnoflorine, jatrorrhizine, palmatine, and berberine) in Cortex berberidis obtained from Qinghai, Tibet and Sichuan Provinces of China. Method validation was performed in terms of precision, repeatability, stability, accuracy, and linearity. Besides, partial least squares discriminant analysis (PLS-DA) and one-way analysis of variance (ANOVA) were applied to study the quality variations of Cortex berberidis from various geographical origins. Results: The proposed HPLC method showed good linearity, precision, repeatability, and accuracy. The four alkaloids were detected in all samples of Cortex berberidis. Among them, magnoflorine (36.46 - 87.30 mg/g) consistently showed the highest amounts in all the samples, followed by berberine (16.00 - 37.50 mg/g). The content varied in the range of 0.66 - 4.57 mg/g for palmatine and 1.53 - 16.26 mg/g for jatrorrhizine, respectively. The total content of the four alkaloids ranged from 67.62 to 114.79 mg/g. Moreover, the results obtained by the PLS-DA and ANOVA showed that magnoflorine level and the total content of these four alkaloids in Qinghai and Tibet samples were significantly higher (p < 0.01) than those in Sichuan samples. Conclusion: Quantification of multi-ingredients by HPLC combined with statistical methods provide an effective approach for achieving origin discrimination and quality evaluation of Cortex berberidis. The quality of Cortex berberidis closely correlates to the geographical origin of the samples, with Cortex berberidis samples from Qinghai and Tibet exhibiting superior qualities to those from Sichuan. [ABSTRACT FROM AUTHOR]