A brief history of Jixian section research

Tian Shuxin

(Tianjin Geological Survey)

The Jixian section was discovered in the early 1930s and published in 1934 by Gao Zhenxi, Xiong Yongxian and Gao Ping . Since then, it has become the standard section of the Sinian system in my country, and the Nankou section is called the classic section.

The currently used stratigraphic unit names at all levels, such as Great Wall, Jixian, Chuanlinggou, Dahongyu, Gaozhuang, Yangzhuang, Wumishan, Shuishizhuang, Tieling, and Jingeryu, are all from Gao Zhenxi selected the place name from the mountainous area in the north of Ji County in 1934. In Gao's stratigraphic division, the name Xiamaling follows Ye Liangfu's name in 1920, and the named place is Xiamaling Village, Mentougou District, Beijing; Qingbaikou is the name of a village 4km southwest of Xiamaling selected by Gao Zhenxi and others.

From 1934 to 1949, there was no significant progress in the research on the "Sinian Series" in Jixian or Yanshan.

From 1949 to 1959, 10 years after the founding of the People's Republic of China, a lot of work was done on the "Chenian system" in Jixian and Yanshan. The authors who published articles include Dong Nanting, Chen Jinbiao, Sun Yunzhu, Shen Qingrong and Liao Da. Wait. The most important progress is that Sun Yunzhu and others discovered that the upper part of the original Jing'eryu Formation should belong to the Lower Cambrian, and that there is an unconformity between it and the "Sinian System", and named the "Jixian Movement" as the structure that produced this unconformity. Movement, designated its standard location in Junshan, the northern prefecture of Ji County.

The First National Stratigraphy Conference in 1959 systematically summarized the results of stratigraphic research in my country and once again affirmed that the Yanshan area "is the most developed area of ??the 'Sinian System' in North China, and its standard location is in Jixian..." , and divided it from top to bottom into Qingbaikou line, Jixian line and Changcheng line. For its era range, it is believed that the upper era limit can be roughly more than 500 million years... the Great Wall System is at least more than 1 billion years ago. From this meeting to 1966, the research on the "Sinian System" in Jixian and Yanshan developed rapidly. Many people published articles, filled in geological maps, and conducted comprehensive studies.

From 1963 to 1964, the Tianjin Institute of Geology and Mineral Resources systematically studied the lithostratigraphy, paleobiostratigraphy, isotope geochronology and geochemistry of the Jixian section. Xing Yusheng et al. research. The on-site academic symposium on the Sinian system in Jixian held in 1964 summarized the above research results and put forward revised opinions on the division and naming of the "Sinian system" in Jixian. The original 10 groups were changed to 11 groups. The carbonate rocks in the upper part of the Linggou Formation were separated separately, and another Tuanshanzi Formation was established. The Huangyaguan Formation (Changzhoucun Formation) was renamed Changzhougou Formation. During this period, Wang Yuelun, Liu Hongyun and others also discussed issues such as the classification, comparison, and era affiliation of the "Sinian lineage" in southern and northern my country.

The Jixian section was re-measured in 1964, and each group was divided into: Changzhougou Formation-Qingshanling Changzhougou Formation section was assigned to Ji Youting and Chen Shouke; Chuancangyu Chuanlinggou Formation section was assigned to Ji Youting and Qiu Shuhou; Tuan The section of Shanzi Formation in Shanzi Village Tuan belongs to Pan Hesheng and Qiu Shuhou; the section of Dahongyu Formation in Dahongyu Valley belongs to Ren Fugen and Lu Songnian; the section of Dahongyugou-Gaozhuang Formation in the north of Quzhuang Village belongs to Chen Jinbiao and Xue Zhizhao; the section of Yangzhuang Formation in Sanjianfang The profiles are Lu Zongbin and Zhang Guangkun; the profiles of the Wumishan Formation from the top of Mopanyu North Mountain to the South Mountain of Mopanyu, Ershilipu and southeast of Hongshuizhuang are Pan Hesheng and Qiu Shuhou; the profiles from the southwest of Dongziling to the Hongshuizhuang Formation at Laohuding are Jiang Yongnian and Feng Qunyue; Lao Hu The Dingtieling Formation profile belongs to Liang Yuzuo and Xue Zhizhao; the Luotuoling-Laoyuding Xiamaling Formation profile belongs to Chen Jinbiao, Pan Hesheng, and Li Zhixin; the Luotuoling-Laoyuding Longshan Formation profile belongs to Chen Jinbiao, Pan Hesheng, Chen Guangkun, and Li Wenguo; Luotuoling-Laoyuding The Jing'eryu Formation section is composed of Chen Jinbiao, Pan Hesheng, Li Zhixin, Chen Guangkun and Li Wenguo.

From 1964 to 1965, the Hebei Provincial Regional Geological Survey Team carried out the K-50-XXXXIV (Xinglong) and J-50-(Baodi) (northern) regional geological surveys.

Since the Chinese Academy of Geological Sciences compiled the geological map of Asia in 1973, the study of the Jixian section and the national Sinian stratigraphy has entered a new stage. Methods such as isotope geochronology, paleomagnetism and biostratigraphy have been widely used, and a series of important progress have been achieved. Zhong Fudao and the Guiyang Institute of Geochemistry, Chinese Academy of Sciences compiled the isotope geological chronology of the "Sinian Series" in the north, mainly Yanshan. A more systematic study was conducted on rocks and algae.

In 1975, based on the need to compile regional stratigraphic tables, a professional conference on the Precambrian in North China was held. The geological significance of the separate establishment of the Tuanshanzi Formation is reiterated. According to the lithology, thickness, distribution and other lithostratigraphic characteristics, the clastic rock series in the lower part of the Jing'eryu Formation is divided and is called the "Longshan Formation". Chen Jinbiao compiled a description of the Jixian section based on the original records and summary data from 1963 to 1964, and published it in the "Regional Stratigraphic Table of North China: Hebei Province and Tianjin City Volume (1)".

In 1975, the "China Sinian System Symposium" was also held. The meeting decided to adopt the temporary stratigraphic name "Shenian Sub-boundary", which includes all strata including the Jixian section and the Xiadong section. The lower limit of its age is about 1700 Ma, and the upper stratigraphic line is the bottom boundary of the Cambrian. It is divided into four internal series, from bottom to top, the Changcheng system, Jixian system, Qingbaikou system and Sinian system. The first three series use the Jixian section as the stratotype, and the Sinian system uses the Xiadong section as the stratotype.

From 1978 to 1979, 6 units including the Tianjin Institute of Geology and Mineral Resources completed the study of representative sections of the "Sinian Sub-boundary" in Jixian County and adjacent areas of Tianjin City, adding a large amount of new data.

In 1979, "Research on the Sinian Sub-boundary Stromatolites in Jixian" compiled by the Tianjin Institute of Geology and Mineral Resources of the State General Administration of Geology, the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, and the Geological Bureau of the Inner Mongolia Autonomous Region was published.

In 1980, Chen Jinbiao, Zhang Huimin, Zhu Shixing, Zhao Zhen, Wang Zhengang and others published the article "Research on the Sinian Sub-boundary in Jixian", which was published in the book "Chinese Sinian Sub-boundary". A systematic and comprehensive summary of the research on the "Danya Boundary" was made, and the following definitions were proposed:

First, the formations represented by the Jixian section and the formations represented by the Hubei Three Gorges section are temporarily based on the pre-1975 The opinions of the Cambrian Symposium are collectively called the Cathay sub-kingdom;

Second, the age range of the Cathay sub-kingdom is about 1950Ma to about 615 Ma;

Third, the Cathay sub-kingdom The subkingdom is part of the Proterozoic universe, above which is the Cambrian system containing fossils of many types of shelled animals;

Fourthly, the Sinian subkingdom is characterized by the massive development of stromatolites and the emergence of eukaryotes. Characteristics;

Fifth, the Sinian sub-kingdom includes 5 series: Changcheng series (1950-1700Ma), Nankou series (1700-1400Ma), Jixian series (1400-1050Ma), Qingbaikou series (1050 ~850Ma) and the Sinian System (850~615Ma);

Sixth, from the Changcheng System to the Jixian System, Yanshan is the most typical, and the standard section is the Jixian Section in Tianjin City. The Qingbaikou system is incomplete in Yanshan, and the Sinian system is missing in North China.

In 1982, the Late Precambrian Strategies Classification and Nomenclature Conference decided to abolish the name "Sinian Sub-Kingdom" and change it to the Mesoproterozoic Boundary. The Mesoproterozoic is temporarily divided into the Changcheng System and Jixian System, and the Neoproterozoic is divided into the Qingbaikou System and the Sinian System. The Late Precambrian strata represented by Jixian use the names of three chronostratigraphic units from bottom to top: Changcheng System, Jixian System, and Qingbaikou System. The name "Sinian System" is limited to the eastern section of the Three Gorges of the Yangtze River in Hubei Province. A section of Late Precambrian strata.

Since the 1980s, the Tianjin Institute of Geology and Mineral Resources has continued to conduct in-depth research on the Jixian section. The research fields include paleontology, paleomagnetism, isotope chronology, geochemistry, and lithostratigraphy; published articles include : Zhang Pengyuan, Zhang Wenzhi, Li Pu, Zhao Zhen, Luo Qiling, Yan Yuzhong, Yu Bingrong, Zhang Xuequi, Wang Changyao, Ren Fugen, Li Zenghui, Lu Songnian, etc.

In 1986, Du Rulin, Tian Lifu, and Li Hanbang published an article titled "Discovery of Macroscopic Biological Fossils from the Gaozhuang Formation of the Changcheng System in Jixian County". A rare macroscopic fossil in the world was discovered in the Gaozhuang Formation of the Changcheng System in Jixian County, Tianjin. The spiral carbonaceous fossils of nuclear organisms have advanced the appearance of macroscopic eukaryotes by at least 200 million to 400 million years, and have attracted great attention at home and abroad.

From 1986 to 1990, the Tianjin Geological Survey Institute carried out a 1:50,000 regional geological survey on both sides of the Jixian section, and identified the spatial distribution of the Mesoproterozoic Boundary in Jixian and its surrounding areas. changing circumstances.

In December 1989, the National Stratigraphy Committee held the "Conference on the Classification and Naming of Chinese Proterozoic Stratigraphic Strategies", which focused on the following discussions: The Proterozoic or Proterozoic realm was renamed the Proterozoic Eon or the Proterozoic Universe and its upper and lower boundaries or the boundary age and other issues; the internal division of the Proterozoic epoch (universe), the boundary (line) age and its name; the symbol issues of each unit. The meeting decided: Cancel the terms "generation" and "boundary" of the first-level chronological and chronostratigraphic units of the Proterozoic period currently used in my country, and adopt the terms "cosm" and "yu" recommended by the International Precambrian Branch. The lower bound is about 2500 Ma. The upper bound is tentatively determined to be about 600 Ma; the Proterozoic is divided into three parts, but according to our country's custom, it is called the Paleozoic, Mesozoic and Neoproterozoic and the corresponding Paleo, Mesozoic and Neoproterozoic realms. The limiting age of the Paleoproterozoic and Mesoproterozoic is 1800 Ma, and the limiting age of the Mesoproterozoic and Neoproterozoic is 1000 Ma. The names and codes of the four chronological and chronological stratigraphic units of the Changchengian, Jixianian, Qingbaikou and Sinian continue to be used; the codes of the Proterozoic continue to be Pt, and the codes of the Paleozoic, Mesozoic and Neoproterozoic continue to be Pt1, Pt2 and Pt3.

In 1992, the "Regional Geology of Tianjin" compiled by the Tianjin Municipal Bureau of Geology and Mineral Resources was published, which summarized the research results of the Mesoproterozoic and Neoproterozoic, and made new progress in geochemical research.

In 1996, "Tianjin Lithostratigraphy" was published under the technical guidance of Chen Jinbiao, which re-clarified the division, comparison standards, definitions, extension range and relationship between the lithostratigraphic units of the Jixian section and other stratigraphic units.

Since the 1990s, with the penetration of new theories such as sequence stratigraphy and cycle stratigraphy, new progress has been made in the study of the Mesoproterozoic and Neoproterozoic in Jixian and Yanshan areas. This aspect has been published. Those who have made research results include Wang Chengshu, Mei Mingxiang, Zhu Shixing, etc.

Around 2000, the Hebei Provincial Institute of Regional Geology and Mineral Resources completed a 1:250,000 Chengde regional geological survey, remeasured the stratotypes of each group in the Jixian section, and proposed that the Jixian Chuancangyu section and Qingshanling The sections were all transformed by later structural deformation, resulting in duplication and deletion of strata, and their thickness cannot represent the true thickness of the area. The Chuanlinggou Formation in Xinglong Dajiancaogou is 606m thick, which can represent the thickness of the standard section in Jixian.