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    20 June 2022, Volume 28 Issue 3
    Cultivate Interest and Promote Innovative Development
    ZHANG Guowei, GUO Anlin, DONG Yunpeng, YAO Anping
    2022, 28(3):  289-293.  DOI: 10.16108/j.issn1006-7493.2021095
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    Facing challenges derived from progress of human society and science and technology, especially state’s development and education improvement of China, educational reform of high-education on geology becomes greatly urgent. Focusing on the topics of teaching reform of physical geology in the meeting of Geosciences Education 2020, we outline our viewpoints in two aspects based on long-term teaching practice and scientific research: 1. Aim and task of physical geology teaching; 2. Principal purposes for teaching physical geology. Beginning with characteristics of Earth science and its teaching, this paper proposes the core value and function of physical geology teaching and further discusses three key aspects for improving the teaching. The three key aspects concern teaching team, aim and positioning, and teaching contents and methods. In conclusion, the overall purpose for the teaching is to build up the broad foundation for students, cultivate and promote their interest in Earth science and, finally, lead them to devote themselves to innovation of Earth science.
    Cultivating Students to be Country’s Backbone Talents with Both Excellent Moral and Scientific Knowledge: Some Thoughts on Teaching the Course of Physical Geology
    SHU Liangshu, WANG Bo, MAO Yafeng
    2022, 28(3):  294-301.  DOI: 10.16108/j.issn1006-7493.2021066
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    Physical Geology is a foundation course of geological education for undergraduate students and plays an important role in linking and leading for the other branch-disciplines of Earth Sciences. It contains the most basic knowledge of various branchdisciplines
    and the liberal education of geosciences. According to the authors’ long-term teaching experiences, we recognized it is necessary and in urgent to integrate classroom teaching, experimental teaching and field geological teaching into a systematic teaching process, the reformation and construction for the curriculum system and teaching contents for the Physical Geology under the modern situation where both elite education and general education are equally important. We should change education thought
    and Conception, and reform traditional education mode and teaching methods to satisfy with modern scientific development and national requirement. A systematical training for students on theoretical knowledge, experimental process and practical ability is very necessary in order to widen students’ knowledge of the Physical Geology, to encourage their interesting of specialty, to advance their creative thinking, and to train gradually their basic ability of modern geology. To do best the works mentioned  above, teaching equality for the education for all-around development will certainly be enhanced and teaching reformation will be greatly promoted. At the same time of teaching the scientific knowledge, it is suggested to carry out necessary ideological and political education with a clear goal, to guide students to recognize the relationship between knowledge and morality, and to make clear the value orientation of the combination of morality and knowledge, so as to improve the teaching quality of basic geology courses and the comprehensive quality of students, and train outstanding talents.

    Thoughts on the Integration of “Four Self-Confidence” Ideological and Political Elements into “General Geology”
    LIU Zheng, TAN Shucheng, HE Xiaohu, TANG Ming
    2022, 28(3):  302-305.  DOI: 10.16108/j.issn1006-7493.2021093
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    “General Geology” is the first introductory course offered by geology majors in Colleges and universities. It is very important to cultivate professional interest and build professional knowledge system. It is also the most ideal course to integrate ideological and political content into the curriculum system of geology majors “four self-confidence” refers to “self-confidence in the socialist road with Chinese characteristics, theory, system and culture”. Integrating the ideological and political elements of “four self- onfidence” into the course of “General Geology” is an important measure to answer the fundamental educational question of “who, how and for whom” in the ideological and political construction of geology courses. From the perspective of geology, this paper discusses in detail the necessity and natural advantages of integrating the ideological and political elements of “four self-confidence” into the course of “General Geology”, as well as the ways and related contents of extracting the ideological and political elements of “four self-confidence”.
    Study of Building A Long-Term Mechanism of Moral Education for Science Courses of Chinese University in the New Era
    YAO Jing
    2022, 28(3):  306-309.  DOI: 10.16108/j.issn1006-7493.2022025
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    The curriculum moral education of science courses of universities closely related to training direction of Chinese talents is an important guarantee realizing national goal of fostering virtue through education. The paper outlines political environment and significance of carrying out a curriculum moral education for science courses in the new era. By a status analysis of the curriculum moral education for science courses of Nanjing University, the author pointed out some shortcomings and issues concealing in the recent moral education of science courses of universities, and proposed constrictive suggestions and measures for improving and promoting the building of long-term mechanism of moral education for science courses of universities in the new era.
    The Introductory Course of Physical Geology as the First Step to Cultivate High-Level Geoscience Talents
    ZHU Zongmin
    2022, 28(3):  310-314.  DOI: 10.16108/j.issn1006-7493.2021071
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    Multi-dimensional education via professional courses is critical to the cultivation of high-level talents in universities and institutes. As the introductory course of geology and its related fields, Physical Geology is mainly aimed to train students for basic knowledge, principles and thoughts of geosciences, and to inspire students’ academic interest. To achieve the educational goal of high-level geoscience talents in the new era, the introductory course needs to strengthen the delivering of the ideological thoughts in a political way, and to shift from the training of basic knowledge and stimulating of academic interest to the promotion of capability in both science and humanity. The Physical Geology course is thus to act as the first step to cultivate high-level geoscience talents. Teachers might make full use of the two core contents of the course, including the principle of ‘the present is the key to the past’ and dynamic geological processes, both of which are able to strengthen the students’ scientific literacy through the promotion on the innovative and interdisciplinary ability. The students can further be trained to show high-level of humanity, including the elaborative craftsman spirit, the global view and the developmental concept, through the delivering of knowledge such as the complexity of geological processes and the large geological spatiotemporal scale.
    Practice and Mode Exploration of Teaching Physical Geology in English
    LIU Zhina, FANG Linhao, YU Fusheng
    2022, 28(3):  315-321.  DOI: 10.16108/j.issn1006-7493.2021094
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    Teaching in English has been implemented in many colleges and universities in order to achieve internationalization of higher education. Since the autumn of 2018, China University of Petroleum-Beijing has begun to recruit international students and implemented English teaching for this class. As such, we started all-English teaching of both theory and field practice of Physical Geology. This paper summarized the experience of all-English teaching for international students, most of whose mother language is not English, and explored the teaching mode and assessment mode. We hope this paper can provide a better way to conduct the all-English teaching mode of Physical Geology in other geological colleges or universities.
    How to Understand the Breadth and Depth in the Teaching of Physical Geology
    ZHENG Wenjun, WANG Weitao, QIAN Jiahui, ZHANG Guifang, ZHANG Dongli, SUN Xin
    2022, 28(3):  322-326.  DOI: 10.16108/j.issn1006-7493.2021097
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    Physical Geology is the first professional enlightenment and guidance course for undergraduate students studying earth sciences. It is not only responsible for the introduction and teaching of professional knowledge but also important for cultivating a correct outlook on life and values of the students and arousing their interest and love of earth sciences. The improvement of the  curriculum content and the breadth and depth of classroom teaching has become an important part of curriculum reform. It’s required for the teachers to grasp the breadth and depth of knowledge points during the pre-class preparation and classroom teaching. The combination of breadth and depth is to make the enlightenment professional curriculum with a teaching method based on interest, science, universality, and classics to assume the responsibility of quality education under the talent training mode in large category. That is the key to inspiring the interest of study. There is a long way for curriculum reform to go, and it requires effort and intellection in many aspects to achieve the expected goals.
    Consideration and Practice of “Small Class Seminar” in Physical Geology
    ZHANG Zhicheng, WU Tairan, HAN Baofu, ZHU Yongfeng, HUANG Baochun, ZHANG Jinjiang
    2022, 28(3):  327-333.  DOI: 10.16108/j.issn1006-7493.2022001
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    Physical Geology is the first professional curriculum for students majoring in geology, and it is an enlightenment course to lead students into the palace of earth science. The curriculum content of Physical Geology covers the basic knowledge of various disciplines of geology. It plays an important role in cultivating the geological thinking of the students. The teaching mode of “tutorial classes” in Physical Geology starts from changing the educational philosophy, focusing on the growth of students, reforming the teaching content and curriculum system, achieving the integration of classroom, discussion, experiment and field, and promoting the close combination of theory and practice. The aim is to stimulate students’ learning interest, learning motivation and exploration spirit. Students’ abilities of self-directed learning, innovative thinking, communication and teamwork are cultivated and improved. The goal of comprehensive, high-level and compound geoscience talents training has been achieved, and the quality of undergraduate talents training has been improved.
    Teaching Refining and Practice of Physical Geology under New Reality of Major Category-Based Admission and Cultivation
    WANG Bo, SHU Liangshu, XIE Guoai, MAO Yafeng, WANG Baojun
    2022, 28(3):  334-341.  DOI: 10.16108/j.issn1006-7493.2021103
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    Major category-based admission and cultivation is a new mode of high education of China, and it challenges the teaching of previous basic courses. This paper summarizes the major problems encountered in teaching of Physical Geology for the category of Earth System Science and Environment of Nanjing University, and introduces our solutions for reforming and refining teaching and the practice result in the past several years. The purpose is to cultivate high level talents in Earth Sciences satisfying the standards of wide academic vision, solid professional competence, highly capable performance and qualified original innovation.
    Teaching Reform and Exploration of the Course of “Introduction to Earth Science” in Higher Education
    ZHANG Fengqi, SHI Xuhua, YANG Xiaoping, CAO Long, LI Yinqi, ZHANG Feng, LIU Yan, CHENG Xiaogan, CHEN Hanlin, YANG Shufeng
    2022, 28(3):  342-346.  DOI: 10.16108/j.issn1006-7493.2021096
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    Under the background of the continuous emergence of new technologies and methods, and with the integration of disciplines, the teaching of Earth science courses is facing unprecedented challenges and opportunities in terms of how to meet the needs of the future development of Earth system science and talent training. This article, taking the course of “Introduction to Earth Science” of Zhejiang University as an example, introduces the expansion of teaching content, the integration of curriculum ideology and politics, the modernization of curriculum teaching, and their challenges and strategies faced by curriculum teaching. We also introduce the direction of future subject development and curriculum-teaching reform. We further point out that the reform of curriculum teaching should be based on morality education and soul-building, consolidate the foundation of Earth science, embrace new technology and new methods, and face the future of Earth system science. 
    Thinking and Practice from Curriculum Reform of the Course “Physical Geology” under the New Circumstance
    NIU Manlan, XU Liqiang, SUN Yi, LI Xiucai, XIE Jiancheng, LI Jiahao, SHEN Yuefeng
    2022, 28(3):  347-351.  DOI: 10.16108/j.issn1006-7493.2021064
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    Under the background of speeding up the construction of “Double First-Class” and the development of crossdisciplines,the traditional earth science is also gradually transforming to the earth system science, which puts forward new expectations and requirements for the cultivation of geoscience talents. In order to better adapt to the needs of industrial development and the development of discipline characteristics, it is necessary to carry out diversified innovation on the training mode of geoscience talents and construct the training system of Geoscience top-notch talents in the contemporary era. “Physical Geology” is a foundational course for geoscience majors. In this paper, the course reform is introduced in the following five aspects: optimizing the teaching syllabus, strengthening the course ideology and politics, paying attention to the guidance of masters, changing the teaching method and advocating the combination of science and technology, so as to carry out beneficial practice and thinking on the training of top geoscience talents.
    Development of Teaching Philosophy and Reform of Introduction to Earth Science
    DAI Jingen, YAN Danping, QIU Liang, CAO Xiuhua
    2022, 28(3):  352-356.  DOI: 10.16108/j.issn1006-7493.2021092
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    “Introduction to Earth Science” is a basic disciplinary course and also the first professional course for junior students major in geology. It undertakes important tasks such as constructing a professional knowledge framework and cultivating interest of students in earth sciences. This paper systematically introduces the development process and achievements of “Introduction to Earth Science” at China University of Geosciences (Beijing), and focuses on the formation process and implementation effects of four teaching concepts such as “teaching the talents”. This paper also emphasizes that high-level teaching team is critical for curriculum construction. After years of teaching practice, a modular teaching system has been proposed, which highlights the key chapters but also has systematic effect. In terms of curriculum design, theoretical and practical lessons have the same amounts of classes, implying the practical characteristics of the course. The teaching method has gradually transitioned from classroom teaching in the past to a combination of classroom teaching, indoor and field geological practice, online learning, and virtual simulation of field practice. The reform and construction of the above-mentioned curriculum system in our university will provide some references for similar courses in related universities.
    The Reform Practice and Effectiveness in Teaching the Physical Geology Course: A Case of Guilin University of Technology
    ZHAO Yilai, KANG Zhiqiang, QIAN Jianping, BAI Lingan, YANG Jinbao, WANG Wen, XU Rongmin
    2022, 28(3):  357-363.  DOI: 10.16108/j.issn1006-7493.2021068
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    The course of Physical Geology of Guilin University of Technology had formed a deep accumulation after years of construction and development. In recent years, the orientation of“macro-geology education”and“macro-engineering education”views and the background of new engineering put forward new requirements for the training of geological students. In accordance with the new requirements, the course of Physical Geology gradually showed some shortcomings: Course knowledge needed to be enriched in terms of inter-disciplinary connection, integration with engineering practice and industry, and the delivery of ideological and political content; The teaching mode was insufficient to cultivate students’ innovative thinking; As the first professional course, it caused cognitive load on students and lack of interest in learning. In response to the above problems, the teaching team has carried out a series of reform practices, adhering to the concept of content update-model change-interest leading: Updating teaching content in textbooks, offline and online teaching; Developing flipped teaching mode based on different teaching methods; Simultaneously building or rebuilding teaching resources. Teaching practice shows that the reform has been effective in improving students’ course performance, as well as in promoting students’ participation in professional competitions, programs for undergraduate innovation and entrepreneurship, and publishing papers. Student evaluations have shown high satisfaction in terms of promoting learning of teaching resources, integration of course content with industry, improvement of students’ classroom participation, expansion of knowledge structure and improvement of comprehensive ability. 

    Teaching Reform and Exploration of the Course“Introduction to Earth Sciences” in the Construction of First-Class Undergraduate Specialty
    XIA Mingzhe, CHENG Hongfei, YANG Xingke, WANG Meng
    2022, 28(3):  364-367.  DOI: 10.16108/j.issn1006-7493.2021067
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    “Introduction to Earth Sciences” is the first professional basic course for students in university who are majored in Geology, with great significance in course construction and teaching reform. Our course team follows the concept of studentcentered teaching, respects students’ subjectivity, adheres to the course objectives, enriches teaching materials resources, expands teaching space and improves teaching quality. Our team adopts the modes of online and offline mixed small class teaching, seminar, in class and field practice, and we are primarily focused on students’ participation and strengthen the cultivation of comprehensive quality. This course is to condense the national feelings and scientific and technological achievements, and to realize the organic unity of value guidance, knowledge education and ability training.
    Field Excursion Design of Orogenic Evolution in the Course of “Field Excursion of the Qinling Orogenic Belt-Ordos Basin”
    SUN Shengsi, DONG Yunpeng
    2022, 28(3):  368-377.  DOI: 10.16108/j.issn1006-7493.2021082
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    Field practice is an indispensable part of geology for the undergraduate students, and it is also a supplement and extension of indoor theory teaching. The juniors have completed their study of major courses after three years, thus the field practice course is designed to inspire and train their innovative thinking and scientific research methods. The“Qinling Orogenic Belt-Ordos Basin Field Excursion”course for senior undergraduates has been set up by the Department of Geology, Northwest University, aiming to helps the students to smoothly transform from study to research. For example, several typical cross-sections crossing the Qinling orogenic belt preserve perfect geological records from subduction to collision, including the ophiolites (remnants of ancient oceanic crust), arc-related volcanic rocks, sedimentary successions, subduction-collisional magmatic and metamorphic rocks. In this paper, we will focus on training the students to reconstruct the tectonic evolution process of the Qinling orogenic belt according to the detailed field investigation on the ophiolitic mélange, deformation, magmatic, metamorphic, and sedimentary records.
    On the Improving Teaching Effect of Basic Geology Practice:An Example from the Practice of Basic Geological Knowledge of Nanjing University#br#
    XIE Guoai, WANG Baojun, WANG Bo, XU Baotian, YANG Aihua, ZHANG Yong
    2022, 28(3):  378-381.  DOI: 10.16108/j.issn1006-7493.2021069
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    Geology is a practical science for understanding the Earth. Field geology practice is an important practical link in the teaching process of geology major, which is an important teaching content of applying knowledge to practice, combining theory with practice, mastering methods of field geology work, and training students’ ability to analyze and solve problems. Taking the practice of basic knowledge teaching of Nanjing university as an example, this paper analyzes the main problems existing in the field geology practice in recent years, analyzes the reasons and puts forward some solutions. In the process of field geological practice, the selection of practice base, the allocation of teachers, the formulation of practice content, the adjustment of practice time and the scoring are effective ways to improve the effect of field geological practice.
    Discussion on the Practice Teaching of General Geological in Geological Engineering Specialty
    XU Baotian, ZHANG Yong, WANG Bo, YANG Aihua, XIE Guoai
    2022, 28(3):  382-386.  DOI: 10.16108/j.issn1006-7493.2021090
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    In view of the importance of general geology in geological engineering specialty, the theory and knowledge of geological engineering should be added into the practice teaching of general geology. The knowledge of general geology and disciplines of engineering are intersected and integrated. The added contents should include three aspects, such as the basic geological characteristics of rocks, mechanical problems, and specific engineering geological problems. Geological knowledge, geological thought and philosophy might expand the students’ vision, so that students can integrate the human engineering activities into the evolution and development of nature on the basis of engineering thought. At the same time, it will achieve the innovation of practice mode, content reform, promotion and development of students’ learning consciousness and autonomous learning, and enhance professional thinking. Rock composition is closely related to rock mechanical properties, weathering characteristics and water softening. The roughness, undulation and filling composition of the joint surface affect the shear resistance and water permeability of the joint surface. The landslide problem is a typical rock mass shear failure, and its mechanical mechanism is the same as that of shear joints. The explanation of connecting the two knowledge points enriches the content of practice. This paper indicates that the phenomena observed in the general practice is closely related to many knowledge points in the professional curriculum of geological engineering. It is completely feasible to integrate the above professional knowledge of geological engineering into the practice teaching of basic geology. If the teaching method of increasing the practical teaching link combined with geological engineering specialty is adopted, it not only expands students’ width of knowledge and initially improves students’ professional quality, but also takes an important first step towards the goal of becoming qualified engineers and scientific researchers in professional fields after graduation.
    Practice and Thoughts on Enhanced Blended Learning Based on Knowledge Graph
    SHI Yukun, XU Shuyi, DONG Shaochun
    2022, 28(3):  387-393.  DOI: 10.16108/j.issn1006-7493.2021085
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    With the rapid development of the internet and information technology, online and offline blended learning has been widely used. Blended learning is a student-centered strategy that focuses on learners’ abilities of self-regulated learning, collaborative learning and personalized learning and has become a creative learning model for higher education. However, the ability to process, sort, and integrate knowledge that students currently demonstrate under such model is obviously far from sufficient, so is their skill to establish a complete knowledge system. As a result, more guidance from the instructors is urgently needed. The current paper analyzes the advantages and disadvantages of blended learning and introduces the concept of knowledge graph in the field of artificial intelligence as a new element to strengthen the self-regulated learning of students, thereby constructing an enhanced blended learning pedagogy based on knowledge graph. This pedagogy was put into practice in the course of Invertebrate Paleontology at Nanjing University in 2020, which has further demonstrated its potential in improving students’ ability of self-regulated learning.
    Teaching Practice and Thinking on the Course of “Principles of Engineering Geology Analysis”
    ZU Fuping, DU Jumin, LIN Xiaoyan, CHEN Yanjun, YUAN Zhen
    2022, 28(3):  394-401.  DOI: 10.16108/j.issn1006-7493.2021105
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    The course of “Principles of Engineering Geology Analysis” is based on the fundamental theories and applied technology of geology. Focusing on engineering stable rock masses and aiming at the needs of national construction and national economic development, it cultivates high-quality talents for the country, through teaching and practical training of basic theories, basic concepts and technical methods. Years of teaching practice has shown that the course has many basic concepts and involves a wide range of knowledge. The engineering process and mechanism analysis require teachers to explain carefully the logic and have three-dimensional thinking, so the teaching is more difficult. Through teaching reform several years’ teaching practice and continuous summary, we have achieved the following teaching reform experience: (1) Keep pace with the times and persist in teaching reform. Combining with the current situation, step by step, reform unreasonable curriculum content and teaching methods, supplement necessary new theories, new technologies, and new methods, and improve curriculum content and teaching methods. (2) Highlight the key points and take into account others. Focus on explaining the basic theories in the field of engineering geology, and appropriately introduce and analyze the humanistic phenomena and environmental protection issues involved. (3) Integrate theory with practice. The teaching of the basic theory of engineering geology must be closely connected with reality, and the introduction of engineering cases should be appropriately added in the teaching to enhance students’ perception and understanding. (4) The teaching method is mainly based on classroom lectures, supplemented by inter-class practice at the engineering site and special seminars by students. Accordingly, the interaction between teachers and students is improved, and the creative thinking of students is stimulated. (5) Curriculum assessment adopts a scoring method that combines theoretical knowledge examination and practical ability. Teaching practice shows that these teaching reform measures we have taken are effective in improving the quality of teaching, and are generally welcomed by students.

    Seismic Ambient Noise Tomography with Dense Linear Arrays and Its Application in the Exploration of the Woxi Au-Sb-W Deposit in Hunan
    WANG Yue, LIU Jiangshan, SHEN Changming, DENG Bao, SU Wenjunliu, CHEN Qifu, LI Junlun
    2022, 28(3):  402-413.  DOI: 10.16108/j.issn1006-7493.2021008
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    The multichannel analysis of surface wave (MASW) method has been widely used in near surface explorations. Accurate extraction of dispersion curves is the key to surface wave imaging. In this study, a new seismic surface wave dispersionimaging method, named the extended range phase shift, is introduced. Based on the traditional phase shift method, the newly proposed method uses the internal arrays to extract dispersions in the medium-to-high frequency range, while it uses the external array to extract dispersions in the low-to-medium frequency range. The two dispersion curves in different frequency ranges are then merged to obtain a new dispersion curve with a wider frequency band, which can be used to invert for the subsurface velocity structure. Not only can this method ensure high-resolution imaging of near surface structures, but also greatly increases the depth which can be effectively constrained by the ambient noise data. From September to October in 2019, we deployed 8 dense linear arrays in Woxi, Hunan Province to collect passive seismic ambient noise data for about one month. We extract the Rayleigh surface wave dispersion curves in the frequency band of 0.1-2 s using the proposed method. Through the preliminary inversion using the background noise data from three dense linear arrays, the S-wave velocity structure down to 2.5 km in depth is obtained. Compared with existing geological evidence, the S-wave velocity inversion result for Line 160 shows a good correspondence with known faults, lithological interfaces and the veins. Also, many new geological features can be interpreted based on the tomographic results showing that the new seismic shear-wave structure for part of the Woxi ore field reflects the ore controlling structures, lithological interfaces and ore body distribution. This provides an important foundation for deep ore exploration in this area. In this study, actual data are used to test the effectiveness of the proposed extended range phase shift method, showing that it is an effective and high-precision imaging method for exploring deep ore fields in the future.

    Active Source Seismic First-arrival Pickup Method Based on Small Sample Convolutional Neural Network
    YU Zhihan, WANG Tao, SUN Pengyuan, WANG Wenchuang, GUO Zhenbo
    2022, 28(3):  414-423.  DOI: 10.16108/j.issn1006-7493.2021060
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    The interpretation of seismic travel-time imaging depends on the accuracy of picking up first arrivals, and it is low efficiency and high cost to pick up arrivals manually. Previous studies showed that deep learning can be applied for automatically picking, but the methods often need a large number of arrivals as the training set. In this study, we trained the U-Net with multichannel images and found that the root mean square error (RMSE) of first P arrivals decreases with the increase in the number of training sets. The errors of 35 and 597 shots are 11.4 and 6.5 ms, respectively. Referring to data augmentation methods in semisupervised
    learning, we selected methods (Random Crop, Random Erase, etc.) suitable for seismic data and applied them to the training set. After random erase of the training sets of 35 shots, the RMSE is less than 5.5 ms (about 3 sampling points), which is 51% less than the error with the original training set. Compared with previous deep learning methods, the augmentation methods can be implemented to pick up the first arrivals with higher precision in the case of small samples.
    Study of 1-D Velocity Structure of Hydrate in Shenhu Area, South China Sea: Based on the Constraints of the Hydrate Zone with Moderate to Low Saturation
    LIU Leifeng, XIA Shaohong, FANG Yunxin, LIN Lin, FAN Chaoyan, SUN Jinlong, Zhao Fang
    2022, 28(3):  424-439.  DOI: 10.16108/j.issn1006-7493.2021010
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    As a common technical means of hydrate research, high-precision OBS surveys can obtain the fine-scale velocity structure of hydrate orebody, which is important for studying gas hydrate saturation, prediction and development of hydrate resources. However, forward simulation of OBS velocity structure is a tedious and time-consuming process, and constructing a reasonable initial model is an important prerequisite for subsequent fast fine-scale structure imaging. Based on data from18 hydrate areas in the world where velocity structures have been identified, this study analyzed the common characteristics and influencing factors of P-wave velocity in hydrate orebodies, and obtained the empirical formula of P-wave velocity in hydrate orebody zone with seawater depth and sediment thickness. Based on the empirical formula, OBS data and multi-channel seismic profiles, an initial model of Shenhu hydrate area is established, and a one-dimensional P-wave velocity structure of Shenhu sea area is obtained by ray tracing and travel-time fitting. The results show that Shenhu hydrate orebody has high P-wave velocity (1.83-1.92 km/s), and free gas has low P-wave velocity (1.60-1.70 km/s). In addition, the empirical formula can serve as an important reference for the simulation of the velocity structure in Shenhu area, and it is expected to provide a reliable initial model for obtaining the two-dimensional / three-dimensional velocity structures in Shenhu sea area so as to guide fine-scale explorations and resource assessments of hydrate.
    Study on the Lithospheric Electrical Structure of Beneath the Central Segment of the Gan-Hang Tectonic Belt
    FANG Jiqi, DENG Juzhi, CHEN Hui, YU Hui, YAN Jiayong
    2022, 28(3):  440-450.  DOI: 10.16108/j.issn1006-7493.2020227
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    The Gan-Hang tectonic belt (GHB) is an important uranium polymetallic ore belt, which is located at the junction of the Yangtze plate and the Cathaysia plate. A series of intermediate-felsic volcano-intrusive rocks are developed in the belt. There are still many controversies about the geodynamic backgrounds of magmatic eruption and intrusion in the belt. Therefore, the magnetotelluric (MT) data collected in the middle part of the Gan-Hang Belt (Shengyuan Basin) and its adjacent areas are processed and inverted by MT phase tensor decomposition technique, two-dimensional nonlinear conjugate gradient method (NLCG), and other technical means to obtain reliable lithospheric electrical structures in the area. The analysis reveals that the shallow volcano-intrusive hybrid rocks in the middle part of the GHB is connected with the southeast downdipping highconductivity band and the deep asthenosphere area, suggesting that the felsic magmatism in the region was controlled by the regional Jiang-Shao deep fracture. In the late Mesozoic lithospheric stretching led to magma rise along the regional deep fracture under the action of intrusion and eruption, forming the volcano-intrusive complexes; The magmatism in the extensional tectonic regime was related to the coeval retreat of the subducting Pacific plate.
    An Audio-Frequency Magnetotellurics (AMT) Investigation of Hard Rock-Hosted Uranium Deposit in Huayangchuan Area, Shaanxi Province
    LI Bo, WANG Peng, RAN Junlin, LIU Kuanhong, YAO Huiming
    2022, 28(3):  451-456.  DOI: 10.16108/j.issn1006-7493.2021009
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    An audio-frequency magnetotellurics (AMT) study has been carried out in the exploration of hard rock-hosted uranium deposits in Huayangchuan area, Shaanxi Province. The results show that the effects of Hz in AMT is significant in restraining the occurrence of structural fractures. Also AMT can effectively detect the scale and occurrence of tectonic-fractured zones and the distribution of rock masses on both sides. Therefore, it is an effective technical means in exploration and peripheral exploration of hard rock type uranium deposits.