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Global Geology

	2022 Vol.25 Issue.3 Published 2022-08-25

	133	The first occurrence of Troodon-morphotype tooth in Jiayin, Heilongjiang, Northeast China
		YU Kaifeng, WU Wenhao, Ivan Bolotsky, ZHANG Xin, SHEN Fengbinand Pascal Godefroit
		Abundant dinosaur remains have been discovered from the Heilongjiang/Amur area for over one hundred years. Among these discoveries, an isolated small theropod tooth recently found from the lower part of the Yuliangzi Formation of Jiayin displays highly distinctive morphological features. It can be identified as a Troodon-morphotype tooth based on mesiodistal constriction at the base of the crown and large, hook-like denticles extending the entire length of both carinae. Previously, Troodon remains were mainly found in North America. Some isolated Troodon teeth were also discovered in Blagoveschensk and Kundur localities on the left bank of the Heilongjiang river. This specimen represents the first occurrence of Troodon-morphotype tooth in Jiayin, Heilongjiang, Northeast China. The presence of this taxon in Jiayin, Blagoveschensk and Kundur localities in the Heilongjiang area provides new evidence for faunal exchange between North America and Asia through Cretaceous Beringia.
		2022 Vol. 25 (3): 133-145 [Abstract] ( 1539 ) [HTML 1KB] [ PDF 42658KB] ( 1814 )

	146	Characteristics and identification of Carboniferous volcanic lithofacies in Shixi area, Junggar Basin
		QIAO Shaozhong, SHAN Xuanlong1, LI Ang1, YI Jian, YIMING Ablimiti and BIAN Baoli
		The identification of volcanic lithofacies is the basis for establishing volcanic institutions and making high-quality reservoir predictions. As the formation of Carboniferous volcanic rocks in Shixi area of Junggar Basin is strongly related to the cyclonic period of volcanic eruption and the location of volcanic channel development, the lithological variety changes rapidly and the lithofacies are complex. Moreover, the volcanic rocks had undergone strong weathering modification at later stage, the identification of volcanic facies becomes more difficult. This paper uses core observation, thin section identification, logging data and seismic attributes to classify and identify the lithology and lithofacies, and to summarize the methods of lithology classification and lithofacies identification of volcanic rocks in the study area. The lithology is mainly andesite and dacite, followed by volcanic breccia and tuff. Basalt and rhyolite develop locally in a few localities. The lithofacies of Carboniferous Period in Shixi area mainly consists of intermediate-acid effusive facies, followed by explosive facies, with basic effusive facies being rare and thinly developed, according to the well data. The volcanic conduit facies is developed only in a few places. The lithofacies are mainly identified based on the characteristics of the logging curves and the combination of external morphology and internal structure of the seismic reflections. The research method of this paper provides a case for the study of Carboniferous volcanic rocks and the dissection of volcanic edifices in Shixi Area.
		2022 Vol. 25 (3): 146-158 [Abstract] ( 355 ) [HTML 1KB] [ PDF 742KB] ( 1786 )

	159	Characteristics of source rocks and hydrocarbon resource prospects of Permian Linxi Formation in northern Songliao Basin
		ZHANG Haihua, GENG Shufeng, ZHANG Jian,SUN Lei,CHEN Shuwang,SU Fei,ZHENG Yuejuan,ZHANG Dejun and BIAN Xiongfei
		In order to explore the oil and gas resource prospects in the Carboniferous–Permian strata in northern Songliao Basin, geological survey boreholes (HFD 1 and HFD 2) were drilled in the area, and thick dark mudstone and slate of the Upper Permian Linxi Formation were encountered. Source rock geochemistry analysis of the samples show that the organic matter abundance of the Upper Permian Linxi Formation source rock in the north of Songliao Basin is high, which belongs to medium to good source rock. The organic matter belongs to type II, and it is in the evolution stage of highly mature to over mature. The Pr/Ph ratios of the source rocks range from 0.16 to 0.93, with an average of 0.53. The phytane predominance is obvious, and indicates a strong reduction to reduction sedimentary environment, which is conducive to the preservation of organic matter. Pr/nC17, Ph/nC18 and C27–C28–C29 regular steranes indicate that the organic matter was derived from a mixture of vascular plants and aquatic organisms such as algae, and is mainly contributed by phytoplankton. Through comprehensive analysis, it is considered that the source rocks of the Upper Permian Linxi Formation in northern Songliao Basin have entered the gas generation stage and have shale gas exploration prospects.
		2022 Vol. 25 (3): 159-173 [Abstract] ( 343 ) [HTML 1KB] [ PDF 514KB] ( 1526 )

	174	Application effect of high-density electrical method on detecting artificial filling layer: A case study of Chengjiangshan area of Huaibei City
		LI Shuai,LIU Lijia, JIA Xiaodong,LI Zhuoyang and HAN Jiangtao
		High-density electrical method has been proved to be an effective method for probing shallow sedimentary layers. It is principally used to identify the boundary between the Quaternary soil layer and bedrock according to the vertical change of apparent resistivity. However, the artificial filling layer has the characteristics of heterogeneity and high porosity, which makes it challenging to detect the artificial filling layer by high-density electrical method. The key to solve this problem is to detect the difference of conductivity between the filling layer and the underlying bedrock. This paper takes the land in Chengjiangshan area of Huaibei City, Anhui Province as the detection target. On the basis of fully analyzing the physical properties of the artificial filling layer, two-dimensional high-density electrical survey and inversion are used to define the thickness of the artificial filling layer. The research shows that the highdensity resistivity method has obvious advantages in delineating the distribution of bedrock and the thickness of the filling layer, and the reliability of the high-density electrical method in the detection of the artificial filling layer, and delineates the scope of the filling layer is verified by the borehole data.
		2022 Vol. 25 (3): 174-181 [Abstract] ( 247 ) [HTML 1KB] [ PDF 491KB] ( 1329 )

	182	Petrophysical evaluation for reservoir properties of Lower Cretaceous sands in Sawan gas field, central Indus Basin, Pakistan
		Ullah Atta, ZHANG Fengjiao and HAN Liguo
		The Sawan gas field (SGF) is located in Pakistan's central Indus Basin in the Province of Sindh, Pakistan. Tectonically, it is part of the southeastern Jacobabad high; and geographically, it is part of the Thar Desert in the Khairpur district. In the present study, three wells, Sawan 01, Sawan 02 and Sawan 08, were analyzed for reservoir properties of the Lower Goru C sand interval, which has been drilled in the central part of the field. Petrophysical parameters such as effective porosity, the volume of shale, formation water resistivity, and water saturation of the studied basin were calculated. In terms of shale volume, Sawan 01 has 30%–35% of non-clean (shale) lithology, which is the highest of the three wells. The effective porosity of the three wells ranges from 12%–16%, while the average water saturation in the interval of C sand in these wells stands around 50%–60%. But there are zones with relatively lower water saturation values of approximately 30%–50%. These zones are considered better pay zones than the rest of the intervals. A very interesting phenomenon that may be termed the "Gas effect" is visible on cross plots, representing the neutron-density cross over on the E-Logs layout and representing the presence of lighter hydrocarbons in this reservoir zone.
		2022 Vol. 25 (3): 182-194 [Abstract] ( 219 ) [HTML 1KB] [ PDF 840KB] ( 1614 )

　

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