25 May 2023, Volume 26 Issue 2

    

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   Two response patterns to negative environmental changes: Cases from Populus and Metasequoia

  ZHANG Yi,XIONG Zhifeng and GUO Shuangxing

  Global Geology. 2023, 26(2): 63-73.

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   Traditionally, plant distribution is thought to be closely related to environmental factors. But recently, it is found that Populus, quite different from other plant taxa, adapted to negative environmental changes, and successfully migrated to different climate zones from its origin places of warm temperate zone. Conversely, Metasequoia is gradually tending to extinction from the Miocene to Quaternary. Based on above contrary cases, two response patterns of plant to negative environmental changes are proposed. One is active adaptation represented by Populus, the other is passive adaptation represented by Metasequoia. The plants of passive strategy characterized for desert prevention might be easily replaced by those of active strategy characterized for desert utilization. Fast growing plants, such as Populus with characteristics of drought and salt tolerance, wind and sand resistance, are selected in Tarim Basin in southern Xinjiang, China, as a good example of desert utilization in the construction of new highways and towns, not only serve as farmland shelterbelt in sandy area. In addition, Populus with high-altitude and cold adaptation has also been selected as an ideal tree planted in Tibet. Therefore, the idea of using Populus as one of the preferred pioneer trees to colonize Mars is proposed.
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   Geochemical characteristics and provenance analysis of Lower Jurassic Badaowan Formation in Changji area of Xinjiang, China

  LIU Zhanjin, XIA Zhaode,LIU Yunhua,DU Jinhua,WANG Shuo,ZHANG Yun

  Global Geology. 2023, 26(2): 74-97.

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   Based on the field survey of Lower Jurassic Badaowan Formation (Fm.) in Changji area of Xinjiang, China, the authors studied the sedimentary environment and provenance characteristics using the analyses of stratigraphic profiles, sedimentary structures, petrography, zircon U-Pb chronology and geochemistry. The results show that Badaowan Fm. deposited in fluvial to swamp shallow-deeplacustrine sedimentary facies deposition. Contents of Sr and ratios of Sr/Cu, Sr/Ba, Th/U, SiO2/Al2O3, V/(V+Ni), V/Cr, and Cu/Zn together indicate that Badaowan Fm. was deposited in an oxygen-poor transitional freshwater environment, under humid climatic conditions. Geochemical characteristics and Q–F–L, Qm–E–Lt , Th–Co–Zr/10, La–Th–Sc, and Th–Sc–Zr/10 discrimination diagrams indicate that the tectonic setting of the source area was a continental island arc environment. Lithological composition, Th/U ratios, and Co/Th–La/Sc, La/Th–Hf, and La/Yb–REE discrimination diagrams show that the source rocks of Badaowan Fm. were upper-crust felsic volcanic rocks. U-Pb dating of detrital zircons yields ages of 1 542.3±15.0 to 232.9±3.3 Ma and mostly in the ranges of 470–410 and 370–280 Ma. A comparison of these ages with the age data from different blocks of crystalline rock in Tianshan Mountains area reveals that the sedimentary rocks in the Badaowan Fm. were sourced predominantly from the central and subordinately from the southern Tianshan Mountains during Early Jurassic.
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   Gold mineralization in Jiaodong Peninsula and destruction of North China Craton: Insights from Mesozoic granite

  WANG Bin, ZHOU Jianbo,DING Zhengjiang, ZHAO Tiqun, SONG Mingchun, BAO Zhongyi, LYU Junyang, XU Shaohui, YAN Chunming, LIU Xiangdong and LIU Jialiang

  Global Geology. 2023, 26(2): 98-113.

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   Large-scale tectonic magmatism and extensive gold mineralization have occurred in the eastern North China Craton (NCC) (Jiaodong and Liaodong peninsulas) since Mesozoic, which indicated that the region experienced decratonization process. The genesis type of granites evolved from S-type to I-type and A-type during Late Jurassic to Early Cretaceous, and thus reflects the evolution of geodynamics in the Late Mesozoic, indicating the varied subduction process of the Paleo-Pacific Plate (PPP) and the craton destruction. The evolution of geochemical features shows that the mantle beneath the Jiaodong Peninsula evolved from EM-II in Jurassic to EM-I in Early Cretaceous, demonstrating that the mantle switched from enriched to depleted. The gold of decratonic gold deposits in Jiaodong Peninsula mainly comes from the lithospheric mantle domains metasomatized by fluids derived from the metamorphism and dehydration of the subducted slab in the mantle transition zone. The rapid decomposition of minerals leads to the concentrated release of ore-forming fluids, and this process leads to the explosive gold mineralization during the craton destruction. Extensive magmatic uplift and extensional structures, triggered by the craton destruction in Early Cretaceous formed the extensional tectonic system, providing space for the decratonic gold deposits in Jiaodong Peninsula.
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   Discussion of reasonable drilling parameters in impregnated diamond bit drilling

  PAK Kumdol, HO Yinchol,PENG Jianming,RI Jaemyong and HAN Changson

  Global Geology. 2023, 26(2): 114-121.

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    The impregnated diamond (ID) bit drilling is one of the main rotary drilling methods in hard rock drilling and it is widely used in mineral exploration, oil and gas exploration, mining, and construction industries. In this study, the quadratic polynomial model in ID bit drilling process was proposed as a function of controllable mechanical operating parameters, such as weight on bit (WOB) and revolutions per minute (RPM). Also, artificial neural networks (ANN) model for predicting the rate of penetration (ROP) was developed using datasets acquired during the drilling operation. The relationships among mechanical operating parameters (WOB and RPM) and ROP in ID bit drilling were analyzed using estimated quadratic polynomial model and trained ANN model. The results show that ROP has an exponential relationship with WOB, whereas ROP has linear relationship with RPM. Finally, the optimal regime of mechanical drilling parameters to achieve high ROP was confirmed using proposed model in combination with rock breaking principal.
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   Classification of vegetative types in Changbai Mountain based on optical and microwave remote sensing data

  YANG Ying,XU Mengxia,LI Sheng,WANG Mingchang,LIU Ziwei and ZHAO Shijun

  Global Geology. 2023, 26(2): 122-132.

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   Highly accurate vegetative type distribution information is of great significance for forestry resource monitoring and management. In order to improve the classification accuracy of forest types, Sentinel-1 and 2 data of Changbai Mountain protection development zone were selected, and combined with DEM to construct a multi-featured random forest type classification model incorporating fusing intensity, texture, spectral, vegetation index and topography information and using random forest Gini index (GI) for optimization. The overall accuracy of classification was 94.60% and the Kappa coefficient was 0.933. Comparing the classification results before and after feature optimization, it shows that feature optimization has a greater impact on the classification accuracy. Comparing the classification results of random forest, maximum likelihood method and CART decision tree under the same conditions, it shows that the random forest has a higher performance and can be applied to forestry research work such as forest resource survey and monitoring.