(1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing10037; 2. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170; 3. Shijiazhuang Institute of Economics, Shijiazhuang, Hebei 05003 1)
Based on the measured data of Li Ying-Wang Jiagou section and Ma Quan Village section of Xiguayuan Formation in Luanping, northern Hebei Province, this section is divided into four lithologic sections and the ostracod biostratigraphic system zoning sequence is established. The isochronous correlation between Yixian Formation in western Liaoning and Xiguayuan Formation in northern Hebei was made, and the sedimentary facies superposition characteristics of the profile were analyzed, which confirmed the sedimentary continuity and sedimentary cycle changes of the profile, identified four third-order sequences of the profile, and determined the definition and demarcation of Yixian period. Therefore, it is suggested to redefine the definition and stratotype of Yixian stage. The Li Ying-Wang Jiagou section in Luanping, northern Hebei Province should be regarded as the unit stratotype of Yixian period of Lower Cretaceous, the boundary section of Dadianzi Formation in Ma Quan village in Luanping, northern Hebei Province should be regarded as the bottom type of Yixian period, and the time limit of watermelon period in Luanping, northern Hebei Province should be regarded as Yixian period. Cancel the sub-sequence of Yixian stage set by the time limit range of Zhangjiagou Dadian subgroup, and change it to Zhangjiagou stage.
Keywords Luxiang stage, candidate stratotype, Luanping basin in northern Hebei Province
Yixian stage is the name put forward by Cretaceous working group at the preparatory meeting of the third national stratigraphic conference held in the Ming Tombs of Beijing in February 1999. The order name and definition originated from Yixian Formation, a lithostratigraphic unit in western Liaoning, and the stratotype profile is temporarily selected between Mashenmiao and Songba Lake in Yixian, western Liaoning [1]. Although Yixian Formation in western Liaoning is rich in world-famous fossil groups, the strata are discontinuous volcanic eruption-deposition sequence, which is difficult to be used as a standard for isochronous division and correlation. In 2004, the National Stratigraphic Committee and the China Geological Survey hosted a symposium on the division of continental Mesozoic stratigraphy and Yixian period in northern Hebei and western Liaoning. According to the minutes of the meeting, "it is still appropriate to choose a sedimentary continuous profile that can fully reflect time continuity, abundant fossils and single lithofacies, and Luanping area in northern Hebei is suitable as a candidate stratotype profile for Dabeigou Stage, Yixian Stage and continental Jurassic-Cretaceous boundary". Supported by the National Stratigraphic Committee and the National Natural Science Foundation of China, the author reselected the stratotype profile of Yixian Stage and revised and supplemented the definition of Yixian Stage by studying the Watermelon Garden Formation in Luanping, northern Hebei, which is equivalent to Yixian Formation in western Liaoning.
1 stratotype section position and description
Watermelon Garden Formation was first built by the Survey Team of the Second District of Hebei Province (1975), and the named section is located between Liying and Watermelon Garden, 3km northeast of Luanping County, northern Hebei Province. The re-selected Yixian stratigraphic section is near the named section, and the specific location is in Xiaonangou-Wangjiagou Village, Nanshan-Xiguayuan, Mars. The stratotype profile of Yixian terrace boundary is selected in Ma Quan Village, 8.5km southwest of Luanping County (Figure 1).
The measured profile (Figure 2) of the Lower Cretaceous Yixian Stage (Watermelon Garden Formation) in Li Ying-Wang Jiagou, Luanping County, northern Hebei Province is described as follows.
The overlying strata of Lower Cretaceous Jiufotang Formation (K 1j) are gray, light gray and grayish white, mixed with medium-thick tuffaceous cemented coarse-grained glutenite.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Figure 1 Location of stratigraphic section and geological schematic diagram of the work area
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Fig. 2 Measured profile of Li Ying-Wang Jiagou Watermelon Garden Formation in Luanping County.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
The second member (K 1d) of the lower Cretaceous Dadianzi Formation in the underlying stratum is purplish red massive gas-rich andesite.
2 Rock Stratigraphic Division
The research on the formation of watermelon orchard in Luanping County, northern Hebei Province has been carried out for decades, but little progress has been made [2,3,4,5]. The reason is that most of the later researchers used the profile and sporadic fossil points measured in1∶ 200,000 regional geological survey (1975). The definition and scope of this rock group have not yet been determined, and its top boundary is initially set at the bottom of the dacliujiagoukou dacite volcanic rock layer in the northeast of the county 1km, and then pushed to the northwest edge of Luanping basin (table 1). In recent years, our research group has re-selected and measured the profile, systematically collected fossils and rock samples, carried out multidisciplinary comprehensive research, and divided and defined the top and bottom boundaries of the group in detail, so that the profile has reached the standard of order building. Rock strata are divided as follows.
The first bottom boundary (1 ~ 2 1 layer) is pseudo-integrated with the purple massive gas-rich andesite of the underlying Dadianzi Formation, and the purple argillaceous cemented andesite conglomerate is above the unconformity surface. The whole lithology of the first member is gray, gray-green, gray-black argillaceous siltstone, silty mudstone and mudstone, with black shale and thin-medium-fine-grained timely sandstone, and the particles are obviously fine. The middle and upper part of this section is purplish red, gray and grayish white medium-thick massive porous andesite and plagioclase rhyolite, mixed with purplish gray and greenish gray massive tuff breccia. This set of volcanic rocks has a stable lateral distribution, which can be traced back to Yanqing Village in the northeast and Xitaizi in the southwest. This set of strata is rich in fossils, and the lower part has the spider of Jehol, the spider of Dabeigou Yanshan and the spider of Elon. New species: Taenia solium, Taenia solium in Yixian, Taenia solium in Longquan, Taenia solium in Dachang, Taenia ovata, Taenia solium, Taenia Xiaolangdi, Taenia solium in Dongguayuan, Taenia Lingyuan and Taenia Luanping in Yumen. November, chicken feet flower, Zhangjiawan, etc. Insect ephemera with three bristles; Ostracoda, carp, etc. Snails, grape prototail snails, etc. Fish, stone pine, etc. The upper part contains eosinophils in watermelon orchard. New species, Xiaolangdi new species, Sun Yingzhi new species 1 1 month, etc. Fish, stone pine, etc.
Table 1 Summary of Division and Evolution of Dabeigou Formation-Watermelon Garden Formation in Luanping, Northern Hebei Province
The bottom boundary of the second section (layers 22-54) is brownish yellow and grayish white thick massive coarse sandstone with fine gravel, with a thickness of about 5 m. This layer of gravel sandstone belongs to the origin of underwater distributary channel, widely distributed and thickened to the northeast, which can be used as a sign layer for lateral recourse. The lithology of this section can be divided into two parts, the lower part is gray, taupe and purplish red thin-medium-fine grained timely sandstone and argillaceous siltstone, gravel sandstone and glutenite; The upper part is mainly gray, gray-black medium-thick mudstone, calcareous mudstone and silty mudstone, which are rich in various algae, and some are black mudstone and shale. The top boundary is marked by the disappearance of large algae mudstone. No animal fossils have been collected in this area.
The bottom boundary of the third section (55-76 layers) is marked by pink and grayish white thin-medium coarse-fine sandstone with a thickness of 8- 10 m, which can trace the extension of this stratum, which is the basis of profile translation. The lithology of the third member is gray, gray-black, gray-green thin-layer argillaceous siltstone and silty mudstone, mixed with gray thin-medium-time fine sandstone and black shale. Most of the gray-black and black shales in the site are rich in fossils, such as Eosestheria aff.middendorfii, E.persculpta, E.jingangshanensis, E.triformis, E. Xiao-Nangouensis sp. Xinxing. Wang Jiagou subspecies nova. , the genus diella. , Yanshan. Insect ephemera with three bristles; Fish and stone pine.
The bottom boundary of the fourth member (77 ~ 98 layers) is brown and purplish red thick layers of fine-grained coarse sandstone, coarse-grained fine conglomerate and coarse-grained medium conglomerate, mixed with gray-green argillaceous fine sandstone, with a thickness of about 4 m. The lithology of this section is obviously divided into two parts according to color and particle size. The lower part is grayish white and grayish green thin-medium-fine grained sandstone, argillaceous siltstone and silty mudstone. The upper part is gray-black, black sheet silty mudstone and shale, mixed with sliding and rolling layered gray gravelly sandstone. The shale interlayer is rich in fossils, including Eosestheria aff.middendorfii, E.per-sculpta, E.jingangshanensis, E.triformis, E.Xiaoangouensis sp.n. New species, Wang Jiagou subspecies N. New species, Yanqing Oriental subspecies New species, see Ellipsophyta, Dunaliella. Yanshan subspecies. Wait. Fish, stone pine, etc. Lycopostracods. Wait. Liaoning ancient trees and flowers; Insect horse chestnut, three-petaled mayfly. The top of this section is gray, gray-green thin-to-medium-fine grained sandstone, silty mudstone sandwiched with lenticular coarse sandstone, and covered with gray, light gray and gray-white tuffaceous cemented coarse sandstone in Jiufotang Formation. The latter belongs to the origin of fan delta, which shows the continuity of upper and lower sediments on the boundary between the two groups.
The establishment of Yixian stage bottom boundary stratotype also needs continuous section at the bottom boundary of Xiguayuan Formation. The author found a continuous section in Ma Quan Village, Huodoushan Town, about 9 kilometers southwest of Luanping County, and made a systematic study (Figure 3). The bottom boundary line is located at the bottom of the 88th floor. The boundary is the semi-deep lake-shallow lake facies deposit of the fourth member of Dadianzi Formation, which is gray, grayish white and grayish green silty mudstone, calcareous mudstone and tuffaceous shale, mixed with thin marl and silty sandstone. Fossils such as ostracods, ostracods and fishes are abundant here. The boundary is covered by light gray and grayish white medium-thick coarse glutenite and fine gravel coarse sandstone mixed with argillaceous sandstone at the bottom of the first member of Xiguayuan Formation, which belongs to fan delta distributary channel deposit. Upward, it is shallow lacustrine gray, grayish white thin-moderately tuffaceous medium-fine composite sandstone, siltstone and silty mudstone, with tuffaceous shale and intermediate-acid volcanic rocks. Cluster shale contains a large number of fossils such as shrimp, turtles, ostracods, insects and fish. The biological markers of the boundary are the disappearance of limb beetle Jiliaoestheria striaris and the appearance of Eosestheria ovata.
Stratigraphic profile of Yixian Stage of Lower Cretaceous in Ma Quan Village, Luanping, northern Hebei Province.
Sedimentary facies sequence and sequence stratigraphy
There is no report on sedimentary facies and sequence stratigraphy of Xiguayuan Formation in Luanping Basin [6]. According to the subsequences (or subsequence groups), more than 130 subsequences (high frequency cycles) can be identified in the profile, and there are 4 tertiary sequences (Figure 4).
The unit stratotype profile (Li Ying-Wang Jiagou) measured by sequence 1(SQ 1) is close to the edge of the basin, in parallel unconformity contact with the underlying strata, the bottom strata are slightly missing, and low-lying area (LST) deposits appear at the bottom of the sequence. 1 ~ 2 section is composed of purplish red argillaceous sandstone cemented andesite conglomerate and grayish green silty mudstone with gravel lens, belonging to onshore riverbed and flood plain subfacies. Lake transgression area (TST) is located in the lower part (layer 3-9) of sequence 1, belonging to shore shallow lake and distributary channel subfacies. It can be proved that the thin-ostracod and gastropod-rich silty sandstone at the bottom of the three layers and the multi-layer sandstone and gravel sandstone at the top develop oblique bedding. The condensed interval (CS) should be in 10 ~ 13 layer, which is gray-black silty mudstone and shale with fine sandstone lens, and belongs to semi-deep lake facies. The HST is 14 ~ 30, and the acidic volcanic rocks in 14 ~ 16 represent the rapid shallow lake basin formed by violent volcanic eruption. Layers 17 ~ 30 are mainly sandstone and siltstone, and the rocks are mostly grayish purple and purplish red, indicating that they belong to shore shallow lake and distributary channel subfacies.
Fossil distribution and multiple stratigraphic division of Li Ying-Wang Jiagou Xiguayuan Formation in Luanping, northern Hebei Province.
Sequence 2(SQ2) The transgressive area of sequence 2 is between 3 1 ~ 49 layers. Layer 3 1 ~ 37 is mainly pink thin-medium-fine grained timely sandstone mixed with argillaceous siltstone, with fine oblique bedding, belonging to lakeside subfacies. Layers 39 ~ 45 are gray and dark gray siltstone, silty mudstone mixed with thin medium-fine sandstone and sandstone lens, which should belong to shallow lake and distributary channel subfacies. Layers 45 ~ 49 are single silty mudstone and calcareous mudstone, which are rich in phycoccolite and belong to shallow lake subfacies. The 50th layer is gray-black mudstone and shale, which is the concentrated interval of deep lake subfacies and sequence 2. The 5 1 ~ 54 layer is a high-level area, and its lithologic characteristics are basically the same as those of the underlying 45 ~ 49 layers, except for adding several layers of mudstone rich in chrysanthemum macroalgae, which belongs to shallow lake subfacies.
Sequence 3(SQ3) The whole sequence 3 is characterized by gray-black, containing a large amount of iron sulfide, stagnant lake water, and shallow water structures such as mud cracks, raindrop marks and wave marks are common in sandstone layers. The bottom 55th ~ 56th layers are mainly purplish red and pink thin-middle-layer timely sandstone, with asymmetrical wavy lines on the surface, belonging to lakeside facies. The lake invasion area is mostly gray-black and black sheet silty mudstone and argillaceous siltstone with thin-medium sandstone, which belongs to semi-closed shallow lake subfacies and occasionally distributary channel sandstone. The concentrated interval should be the black shale interlayer of the 69th ~ 70th layer. The shallow lake subfacies in the high-level domain (7 1 ~ 76 layers) are gray-white, gray-green thin-middle composite sandstone and silty mudstone, and the lake water body has been unobstructed.
Sequence 4(SQ4) Sequence 4 is characterized by the appearance of typical semi-deep lake and deep lake subfacies, indicating the rapid subsidence of the lake bottom. The bottom (layer 77) is purplish red thin-medium coarse glutenite and coarse sandstone mixed with fine gravel, belonging to lakeside subfacies. Most of the lake invaded areas (78-86 layers) belong to shallow lake subfacies and distributary channel subfacies, and the sandstone in 87-89 layers has massive cyclotron bedding, which indicates that it is the slump accumulation of semi-deep lake subfacies. The tight intervals (90th ~ 93rd layers) are dark gray and black tabular mudstones and shales in deep lacustrine facies. Slow gravelly sandstone with semi-deep lake subfacies appears in the 94th ~ 95th layers of high-level domain. The 96th ~ 98th layers changed into gray, gray-green siltstone and silty mudstone of shallow lake subfacies, with gravel and sandstone lenses, indicating that the lake bottom rose rapidly. Finally (99th floor), the fan delta subfacies of Jiufotang Formation are filled and covered by glutenite.
Biostratigraphy and its correlation with Yixian Formation
The fossils collected by predecessors in the Xiguayuan Formation are sporadic, and there are few systematic studies, and the biostratigraphic sequence has not been established. In recent years, through systematic and extensive collection and in-depth study (Figure 4), five arachnid stratigraphic zones have been established, and other fossils with important comparative significance have been found, such as cricothyroid fish, Liaoning Australopithecus, and black mountain seven-leaf moss. The zoning of mesophyll layer is briefly described as follows, and the detailed discussion will be published in another paper.
(1) Heteroacidophilus ovoid zone: characterized by the extension of Heteroacidophilus ovoid, the important components are Heteroacidophilus Gongyingzi, Heteroacidophilus Jilin, Heteroacidophilus Lingyuan, etc. This fossil belt is also found in Jianshangou or Yenangou layers of Yixian Formation in western Liaoning.
(2) Dirichlet zone in Jehol: characterized by the extension of Dirichlet Jehol, and other components are Eosestheria sp., Yanshan Mountain in Dabeigou, Elytrigia elongata, etc. The marker fossils of this zone were also found in the upper part of the garden layer of Yixian Formation in western Liaoning.
(3) Died in Yixian -D. Long Inqua assemblage zone of RIA: characterized by the * * * retention limit of two fossils. Among them, the important components are Dirichlet Yixian, Dirichlet Longquan, Dirichlet Wolverine, Dirichlet Liyin, Dirichlet Xiaolangdi and Taenia qingquanensis. The Yixian Echinococcus belt similar to this belt was also found in Dakangbao layer of Yixian Formation in western Liaoning.
(4) Isos-Nenisols assemblage zone in watermelon orchard: characterized by the * * * retention limit of two fossils. The ingredients are Sun Yingzi and so on. The three species found so far are all new species, and this assemblage has not been found between Dakangbao layer and Jingangshan layer of Yixian Formation in western Liaoning, which is a unique fossil assemblage in Xiguayuan Formation in Luanping Basin.
(5)eosesteria aff。 Middendorfii-E. Persculpta assemblage zone: characterized by the * * * persistence limit of two fossils. The important components are eosinophil, alpine eosinophil, Mount Kumgang eosinophil, trefoil eosinophil, Xiaonangou eosinophil, Wang Jiagou eosinophil and Alternaria. Yanshan subspecies. Wait. Eosestheria aff.middendorfii belt, which is similar to this belt, was found in Zhujiagou layer to Jingangshan layer of Yixian Formation in western Liaoning.
In recent years, the age comparison between Yixian Formation in western Liaoning and the corresponding strata in northern Hebei has emerged with the in-depth study of Luanping strata in northern Hebei. There are three different opinions: ① Comparison between Yixian Formation in western Liaoning and Watermelon Garden Formation in northern Hebei [7,8]; ② Yixian Formation in western Liaoning is equivalent to Dadianzi Formation-Watermelon Garden Formation in northern Hebei [9,10]; ③ Yixian Formation in western Liaoning is equivalent to Xiguayuan Formation in the upper part of Dadianzi Formation in northern Hebei [9, 1 1, 12]. The key to solve this problem is to find the same fossil belt (or combination) and the marker fossils with comparative significance in the two places.
The study of paleontological fossils in Yixian Formation in western Liaoning has been quite in-depth, but the Arachidae [9 10, 13, 14, 15, 16] can establish a relatively complete biostratigraphic sequence. On the basis of previous work, Yixian Formation in western Liaoning identified three ostracod fossil belts (or combinations) in different volcanic sedimentary interlayers. From bottom to top, it is the Eosestheriaovata belt (or combination) of Jianshangou or Yenangou layer, Diestheriayixianensis belt (or combination) of Dakangbao layer and Eosestheriaaff.middendorfii of Zhujiagou to Mount Kumgang layer. In addition to vertebrates, there are fossils with important correlation significance, including Heishangou Yanting AeschnidiumheishankowenseZhang, 1999, which are widely distributed in Beipiao Formation, Yixian Formation and Lingyuan Yixian Formation in western Liaoning. Archaefruc-Tusliangensis (Sun et al., 1998), an ancient fruit in Liaoning Province, is produced in Jianshangou layer of Shangyuan Town, beipiao city. The crayfish assemblage at the bottom of Yixian Formation in Daxinfangzi, Dawangzhangzi, Songzhangzi and Niuyingzi areas of Lingyuan is represented by CricodoscelosusaethusTaylor, SchramandShen, 1999.
Summary table of multiple stratigraphic division and correlation in Yixian period of early Cretaceous in northern Hebei-western Liaoning.
Research report on the construction of major dating strata in China: 2006 ~ 2009.
The above-mentioned paleontological stratigraphic data of northern Hebei-western Liaoning clearly show that the ostracod zoning of Yixian Formation in western Liaoning and the important fossils that can be mainly used for correlation have been found in Xiguayuan Formation in northern Hebei. In particular, a large number of crayfish assemblages and ostracods Eosestheriaaff.middendorfii define the top and bottom boundaries of Yixian Formation and Watermelon Garden Formation. In stratigraphic age, Yixian Formation in western Liaoning can be completely compared with Xiguayuan Formation in northern Hebei, which also provides strong evidence for the establishment of Yixian stage unit and boundary stratotype in Luanping Basin in northern Hebei.
5 Redefinition of Yixian Grade
The initial period of Yixian period [1] was upgraded from Yixian formation in western Liaoning, and the definition range was the time limit included in Yixian formation. Tian Shugang et al. [2] established the "lower suborder of Yixian stage" and stratotype section on the basis of studying the Dadian subgroup of Zhangjiagou in Luanping, northern Hebei Province, and called the original time limit of Yixian stage "upper suborder of Yixian stage". Through the comprehensive study of watermelon orchard in Luanping, northern Hebei Province in recent years and the isochronous comparison with Yixian Formation in western Liaoning Province, it is confirmed that Yixian Formation in western Liaoning Province is only equivalent to watermelon orchard in northern Hebei Province. Therefore, the author thinks that the definition of Yixian stage should be redefined and its stratotype profile should be determined. It is suggested that the time limit range of Watermelon Garden Formation in Luanping, northern Hebei Province should be defined as Yixian Stage, the Li Ying-Wang Jiagou section in Luanping, northern Hebei Province should be defined as the unit stratotype of Yixian Stage of Lower Cretaceous, and the boundary section between Dadianzi Formation and Watermelon Garden Formation in Ma Quan Village in Luanping, northern Hebei Province should be defined as the bottom type of Yixian Stage. However, the sub-sequence of Yixian stage set within the time limit of Zhangjiagou Dadian subgroup was cancelled and changed to Zhangjiagou stage.
The reasons are as follows: (1) Observe the time limit defined when Yixian stage was first established, and define Yixian stage according to the time limit of Watermelon Garden Group, so as not to cause confusion in guiding research; ② The time limit of the original definition of Yixian terrace is long enough, reaching 8 ~ 9ma (Wang et al., 2004, table 2-4- 1) [10], which is much longer than the underlying Zhangjiagou terrace and the overlying Jiufotang terrace; ③ Yixian stage and Zhangjiagou stage belong to different stages of biota evolution and crustal development. Yixian period is the flourishing stage of Jehol biota, with a wide variety; Strata were widely distributed in this period, starting from Lake Baikal in Russia in the north and reaching Central Asia in the west [14, 15]. The Dadianzi Formation of Zhangjiagou Stage is only found in northern Hebei at present.
I would like to thank Wang Sien, a researcher from Institute of Geology, Chinese Academy of Geological Sciences, for his valuable advice during the writing of this paper, and I would like to express my heartfelt thanks.
Main references
National stratigraphic committee. Notes on the Chronostratigraphy (Geochronology) Table of China Region [M]. Beijing: Geological Publishing House, 2002: 1 ~ 72.
Wang Sien. Origin, Evolution and Mechanism of Jehol Fauna [J]. Journal of Geology,1990,64 (4): 350 ~ 360.
Wang Sien, Zheng Shaolin, Yu Jingshan, et al. Code of Jurassic strata in China [M]. Beijing: Geological Publishing House, 2000: 1 ~ 154.
Hao Yichun, Su Deying, Yu Jingxian, et al. Code of Cretaceous strata in China [M]. Beijing: Geological Publishing House, 2000: 1 ~ 124.
Niu Shaowu, Li Peixian, Tian Shugang, et al. Discovery of the genus Cyclophyllum from Dadianzi Formation in Luanping Basin, northern Hebei Province and its significance [J]. Geological Bulletin, 2003,22 (2): 95 ~104
Tian Shugang, Liu Yongqing, Li Peixian, et al. Study on Sequence Stratigraphy of Jurassic-Cretaceous Boundary in Luanping Area of Northern Hebei [J]. China (Series D), 2003,33 (9): 871~ 880.
Tian Shugang, Pang Qiqing, Niu Shaowu, et al. Preliminary study on candidate stratotype profiles of continental Jurassic-Cretaceous boundary [J]. Geological Bulletin, 2004,23 (12):170 ~1/kloc.
Tian Shugang, Wang Naiwen. Understanding and thinking on establishing continental stratotype [J]. journal of palaeogeography, 2005,7 (4): 561~ 569.
Wang Wuli, Zhang Hong, Zhang Lijun, et al. Stratigraphic sequence of Yixian Formation in Yixian-Beipiao area, Liaoning Province-Establishment and study of Yixian standard stratigraphic profile [J]. Journal of Stratigraphy, 2003,27 (3), 227 ~ 232.
Wang Wuli, Zhang Hong, Zhang Lijun, et al. Standard stratigraphic profiles of Tuchengzi and Yixian periods and their stratigraphic paleontology, tectonics-volcanism [M]. Beijing, Geological Publishing House, 2004, 1 ~ 5 14, 37th edition.
[1 1] Pang Qiqing, Li Peixian, Tian Shugang, et al. Discovery of Ostracoda and Study on Biostratigraphic Boundary of the Dabeigou Formation in Zhangjiagou, Luanping, Northern Hebei [J]. Geological Bulletin, 2002,21(6): 329 ~ 338.
[12] Pang Qiqing, Tian Shugang, Li Peixian, Niu Shaowu, et al. Ostracoda biostratigraphy and Jurassic-Cretaceous boundary of Dabeigou Formation-Dadianzi Formation in Luanping Basin, northern Hebei Province [J]. Geological Bulletin, 2006,25 (3): 348 ~ 356
[13], Chen Piji, Shen. Ostracoda from China [M]. Beijing, Science Press, 1976
[14] Chen Piji, edited by Jin Fan. Jehol biota [M]. Ancient World 1 1, 1999, Hefei, University of Science and Technology of China Press, 1 ~ 342.
[15] Chen Piji. Distribution and Migration of the Jehol Fauna —— On the Division of the Jurassic-Cretaceous Boundary in China [J]. Acta Palaeontologica1988,27 (6): 659 ~ 683.
Chen Piji, Wang, et al. Study on Jianshangou Formation of Yixian Formation [J]. China Science (Series D), 2004,34 (10): 883 ~ 895.
[17] Gu Zhiwei. Jurassic and Cretaceous in China [M]. Beijing, Science Press, 1962.
Liu Benpei, Chen Fen, Wang Wuli. Discussion on the continental Jurassic-Cretaceous boundary in East Asia from the perspective of event stratigraphy [J]. Geoscience, 1986, 1 1 (5): 465 ~ 472.
[19] Gradstein F.M et al., translated by Jin Yugan et al. International Stratigraphic Table (2004) [J]. Journal of Stratigraphy, 2005,29 (2): 98.
[20] Murphy and El Salvador Company 1999. International stratigraphic guide-abridged edition [J]. Episode 22 (4): 255 ~27 1
[21] Remane J., Bassett M.G, Cowie J.W et al. Revised Guidelines of International Stratigraphic Commission (ICS) on Establishing Global Chronostratigraphic Standards [J]. Series, 1996, 19(3): 77 ~ 8 1
County steps and stratotype candidates of lower Cretaceous continental facies
Tian Shugang (Tian Shugang) 1 Niu Shaowu (Niu Shaowu) 2 Pang Qing (2 Pang Qiqing) 3
(1.CAGS Institute of Geology, Beijing100037; 2. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170; 3. Shijiazhuang Institute of Economics, Shijiazhuang, Hebei 065000)
According to the standard of establishing stratotype, the Mars-Wang Jiagou section and Ma Juan section of Xiguayuan Formation in Luanping County were systematically studied. By adopting a multi-level method, the section was divided into four lithologic sections, and the ostracod biostratigraphic sequence (five zones) was established. The chronology of Yixian Formation in western Liaoning Province and Xiguayuan Formation in northern Hebei Province was compared, the sedimentary environment and cycle changes were analyzed, and four third-order sequences were divided. Therefore, it is suggested that the Mars-Wang Jiagou section should be taken as the unit stratotype candidate section of Yixian stage, and the Ma Juan section as the bottom stratotype candidate section of Yixian stage, and the age range of Xiguayuan Nian Formation should be limited to Yixian stage. Originally called Yixian sub-stage, it can be changed to Zhangjiagou stage.
Candidate of continental Yixian stage and stratotype in Luanping basin
Chart illustration
(All specimens are kept in Institute of Geology, Chinese Academy of Geological Sciences)
License plate 1
1. Pepstes species. . Fin, acquisition horizon: PM-26, at the bottom of the Lower Cretaceous Watermelon Garden Formation at the boundary between Dadianzi Formation and Watermelon Garden Formation in Maquan Village.
2, 5. Liaoning archaea (Sun et al., 1998). Branches and leaves. Collection horizon: 07xn-3 1. Upper part of Lower Cretaceous Watermelon Garden Formation in Xiaonangou section of Wangjiagou village.
3. fruit? Seeds? Acquisition horizon: PM-2 1, at the bottom of the Lower Cretaceous Watermelon Formation at the boundary between Dadianzi Formation and Watermelon Formation in Maquancun.
4,9, 10. Holotrichia, Shi Lamu and Shen, 1999 .4. Head and abdomen view; 9. Back view; 10. Rear view. Acquisition horizon: PM-2 1, at the bottom of the Lower Cretaceous Watermelon Formation at the boundary between Dadianzi Formation and Watermelon Formation in Maquancun.
6, 1 1. Senecio Montenegro, Zhang, 1999 .6. Head and chest vision; 1 1. Tail vision. Acquisition horizon: 07xn-3 1, upper part of Lower Cretaceous Watermelon Garden Formation in Xiaonangou section of Wangjiagou village.
7, 12. Ephedra trifolia, 1864 .7. Forward mode; 12. Deputy mold. Acquisition horizon: 07xn-3 1, upper part of Lower Cretaceous Watermelon Garden Formation in Xiaonangou section of Wangjiagou village.
8, 13. Lycopodium (Sauvage, 1880).8. Forward mode; 13. Deputy mold. Acquisition horizon: PM-26, at the bottom of the Lower Cretaceous Watermelon Garden Formation at the boundary between Dadianzi Formation and Watermelon Garden Formation in Ma Quan Village.
Plate 2
1, 2 ovoid heteroeosinophils (Chen,1976).1a. External mold of right valve, registration number: 05LS 100e- 1, ×1.5; 1b。 The same specimen, the front abdomen is decorated with a grid, × 30.
2a。 External mold of left valve, registration number: 05 100e-3, × 2. 2b。 The ventral reticulation of the same specimen is × 40. The lower part of the first section of Xiguayuan Formation in Lahaigou, Huodoushan Township, Luanping.
3. Gongyingzi eosinophilia. 3a. External mold of right valve, registration number: 05ls 100e-5, × 2.3; 3b。 The front and abdomen edges of the same specimen are decorated with net wires, × 40. The lower part of the first section of Xiguayuan Formation in Lahaigou, Huodoushan Township, Luanping.
4, 5. Dieffenbach in Yixian County,1976.4a. Right valve, registration number: 06xlg0 1e- 1, ×1.9; 4b。 Frontal reticular decoration and overlapping reticular structure in the same specimen, × 30. 5a。 Right valve, registration number: 05xlg 1e- 1, ×1.8; 5b。 Ridge and overlapping reticular structure at the anterior ventral margin of the same specimen, × 30. Xiaolanggou, south of Luanping Watermelon Garden, forms a group in the middle of the first section.
6. Butterfly in Jehol,1953.6a. Right valve, registration number: 04mjz23e- 1, ×1.5; 6b。 The line ridge and overlapping reticular structure of the anterior ventral margin of the same specimen, ×30. The lower part of the first section of Xiguayuan Formation in Lahaigou, Huodoushan Township, Luanping.
7 ~ 8. Long-billed butterfly, Chen,1976.7a. Left valve, registration number: 06xlg0 1e-3, ×1.4; 7b。 Ridge-like and overlapping reticular structures at the posterior ventral margin of the same specimen, × 30. The origin horizon is the same as above. 8a。 Left valve, registration number: 06xlg0 1e-4, ×1.5; 8b。 Ridge and overlapping reticular structure at the anterior ventral margin of the same specimen, × 30. Luanping Watermelon Garden is located in the south of Li Ying, in the middle of Group 1 of Watermelon Garden.
9 ~ 10. Niu, 2008.9a. External mold of right valve and partial left valve, registration number: 05xlg 1e-6, × 2.2; 9b。 The structure of the greater reticular and overlapping reticular in the anterior ventral margin of the same specimen, ×30. 10a。 External mold of left valve, male mold, registration number: 05xlg2e-3, × 2; 10b。 Anterior abdominal grid ridge decoration of the same specimen, × 35. Xiaolanggou, south of Luanping Watermelon Garden, forms a group in the middle of the first section.
1 1 ~ 12. Oxophilic tumor cattle in watermelon orchard, 2008.11a. External mold of right valve, male mold, registration number: 05xlg2e- 1, × 2; 1 1b。 The plaid ridge decoration on the front abdomen of the same specimen, ×35. 12a。 External mold of left valve, auxiliary mold, registration number: 05xlg2e-2, × 2.2; 12b。 The mesh ridge of the anterior abdomen of the same specimen, ×35. Xiaolanggou, south of Luanping Watermelon Garden, on the upper part of the lower part of Watermelon Garden.
13 ~ 14.Eosestheria aff。 Middendorfii (Jones, 1862). 13a. Left valve external mold, registration number: 06xnG9E- 1, ×1.7; 13b。 The mesh ridge of the anterior abdomen of the same specimen, × 40. 14a。 External mold of left valve, registration number: 06xnG9E-2, × 2; 14b。 In the same specimen, there are lines and lines in the abdomen, × 40. The watermelon garden in Luanping is located in Xiaonangou, the third section of watermelon garden group.
15 ~ 16. ladybug, 1976. 15a. Right valve, registration number: 06xng28e-8, ×1.6; 15b。 Lines and ridges arranged in pairs on the front and abdomen of the same specimen, ×40. 16a。 Right valve, registration number: 06xng28e-6, ×1.7; 16b。 Lines and ridges arranged in pairs on the front and abdomen of the same specimen, × 40. The watermelon garden in Luanping is located in Xiaonangou, the third section of watermelon garden group.
License plate 1
Plate 2