25 November 2021, Volume 24 Issue 4

    

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  Ｒecent advance in study of K-Pg boundary in Jiayin of Heilongjiang，China and its adjacent area

  SUN Ge,SUN Chunlin,SUN Yuewu,ZHANG Shuqin,WU Wenhao， YANG Tao,LIANG Fei,FENG Yuhui,Markevich V,Ashraf A Ｒ,Bugdaeva E．,Tekleva M． and Suzuki S．

  Global Geology. 2021, 24(4): 189-197.

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  The non-marine Cretaceous-Paleogene boundary ( KPgB) in Jiayin of Heilongjiang was first defined and reported in China by the authors' research team in 2011． Thereafter the continuous research on the KPgB and its related Late Cretaceous biota in Jiayin has been made by the authors in 2012-2020． The achievements of the research are mainly reflected as follows: ( 1) a new drilling borehole with 60 m in depth carried out in the Xiaoheyan of Jiayin in 2016，supplemented new palynological evidence for the KPgB definition in 2011; ( 2)some radiometric dating newly made on the strata related to the KPgB in Jiayin and its neighboring Ｒussian area，provided the supplemental evidence for the KPgB definition in Jiayin; ( 3) many new fossils found by the authors，represented by the angiosperms Dalembia and Nelumbo，refresh understanding the Late Cretaceous environment of Jiayin; and ( 4) the TEM method is applied in the study of pollen exine ultrastructure of Pseudointegricorpus，Wodehouseia，and Aquilapollenites，promoting the late Maastrichtian ecological study in Jiayin，related to the KPgB．
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  Middle and Late Permian palynoflora in Tianshan Township， southeast of Bogda Mountain，Xinjiang，China

  Muhammad I． Asghar,ZHANG Shuqin,ZHANG Minda,SHI Xiao and SUN Yuewu

  Global Geology. 2021, 24(4): 198-212.

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  The Permian is one of the most important periods during which the vegetative earth witnessed the transition from icehouse to greenhouse climate and the global environment changes． Organisms on the planet encountered great challenge and the demise of swamp caused the extinction of arborescent lycopods and the rising of Mesophytic plants accomplished the floral transition from the Paleophytic to Mesophytic vegetation． In order to depict the climatic changes and floral succession in the middle and high latitudes of the North Hemisphere，palynological investigation was engaged，and 40 samples collected from the uppermost of Taerlang Formation，Hongyanchi Formation and Quanzijie Formation in the Tianshan Town，Turpan-Hami Basin，eastern Xinjiang，China． The result shows that the palynoflora in the studied area is composed of 50 species of 33 genera，dominated by disaccites and striatiti gymnosperm pollen，and characterized by diverse Protohaploxypinus，Hamiapollenites，Alisporites and Klausipollenites． It is quite similar to those Middle and Late Permian palynological assemblages reported in the Dalongkou section and other localities in southern margin of Junggar Basin，and aged at Middle and Late Permian． The diversity of typical Angara and sub-Angara pollen，such as Falcisporites，Alisporites，Protohaploxypinus，Vittatina，Lunatisporites，Hamiapollenites，etc． indicates that the studied palynoflora belonged to the sub-Angara phytoprovince，while the presence of Lueckisporites virkkiae implied Euramerica pollen intruded northward sometimes． The paleoclimate of the studied area might be warm and humid with fluctuated dry seasons during the late Guadalupian and early Lopingian time
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  Organic geochemistry and source rock potential assessment of Late Paleocene Patala Formation in Margalla Hill Ｒange，North Pakistan

  Shams M． Kamran,WANG Pujun,Nasar Khan and Muhammad Hassan

  Global Geology. 2021, 24(4): 213-225.

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  Black shales of the Paleocene Patala Formation are proven source rocks for conventional hydrocarbons in southern Potwar Basin of Pakistan and are assumed to be effective source rocks towards north in the Margalla Hill Ｒange of Pakistan． In this regard，the current study focuses on source rock geochemistry of the Paleocene Patala Formation to assess its source rock potential，organic matter types and thermal maturity levels in the Margalla Hill Ｒange of North Pakistan． Source rock generative potential，kerogen types and thermal maturation of the analysed rock samples were unraveled by using Ｒock-Eval pyrolysis Tmax，TOC ( total organic carbon) and vitrinite reflectance ( Ｒ0 ) analyses． TOC analysis coupled with S2 yield revealed poor to fair source rock quality encountered within the formation． The pyrolysis Tmax vs Hydrogen Index ( HI) ，showed mostly Type III kerogen dominated by thermally immature to mature organic matter． The HI and genetic potential is low and revealed poor hydrocarbon generation potential of the formation． The S1 vs TOC plots confirm the indigenous nature of the hydrocarbons hosted by Patala Formation． The vitrinite reflectance outcomes indicated immature to mature source rock beds lying in dry gas zone． The HI and OI signatures and abundance of Type III kerogen are indicating dominance of terrestrial organic matter within the formation． Overall，the investigated Patala Formation exposed at the studied section of Margalla Hill Ｒange，Pakistan acts as a poor source rock unit for liquid hydrocarbon generation but holds prospects for dry gas generation in the study area．
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  Deblending by modified dictionary learning using Sparse Parameter Training

  Evinemi E Isaac,MAO Weijian and CHENG Shijun

  Global Geology. 2021, 24(4): 226-238.

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  Considerable attempts have been made on removing the crosstalk noise in a simultaneous source data using the popular K-means Singular Value Decomposition algorithm ( KSVD) ． Several hybrids of this method have been designed and successfully deployed，but the complex nature of blending noise makes it difficult to manipulate easily． One of the challenges of the K-means Singular Value Decomposition approach is the challenge to obtain an exact KSVD for each data patch which is believed to result in a better output． In this work，we propose a learnable architecture capable of data training while retaining the K-means Singular Value Decomposition essence to deblend simultaneous source data
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  Forward simulation of coal fire model by transient electromagnetic method with electrical source

  ZENG Fanjie,SONG Shuanlin and WANG Zhejiang

  Global Geology. 2021, 24(4): 239-248.

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  Uncontrolled coal fires are natural disasters that may cause mineral loss and environmental damage． The traditional loop source transient electromagnetic method can effectively detect the low-resistivity region of coal fires，but its detection efficiency is not so good for high-resistivity regions． In view of this limitation，a technique based on electrical source transient electromagnetics is proposed in this paper to detect high-resistivity regions in the spontaneous combustion process of coal． Considering the complex geometry of the coal fire area，an unstructured tetrahedral grid is used in this study to realize the spatial discretization of the model，and solve the electromagnetic field based on a vector finite element algorithm． Numerical analysis is used to investigate methods for detecting coal fires and the characteristics of effective anomalies are further examined to provide guidance for practical detection．
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  2021 Vol． 24 Nos． 1 ～ 4 CONTENTS

  Global Geology. 2021, 24(4): 249-250.

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