Dabeigoucun-Lahailiang Section in Luanping Basin
Watermelon orchard layer of Yixian Formation overlying rock: yellow-brown thick conglomerate.
inconformity
Yixian Formation: 296.19m.
Shop floor:
Sediment:
13. Dark shale mixed with thin marl, the limestone layer is 30 ~ 40 m thick, and the ***2 layer is 6.64 m thick.
Fig. 2-2- 19 Dabeigou Village-Lahailiang Auxiliary Boundary Stratum, Luanping County, Hebei Province
Volcanic rock layer:
12. Light green and dark purple almonds and stomatal andesite 8.29m.
1 1. Dark green and yellow green compact andesite
10. Grey-green, yellow-green almond-shaped andesite 4.42m.
Sediment:
9. Gray and dark gray marl mixed with calcareous shale. Fish production: perch; ; Arthropods: eosensitia (diformagrapta) gibba, E.spp, eosensitia (filigrapta) Bella; Ostracoda: Cypridea aff.vitimensis, C.reheensis, Timiriasevia polymorpha, T.opinabilis, Mongolianella gi-gantea, Djungarica Camarata (= Mongolian ella Khamariniensis), Damonella circulata；; Plant: Equisetum. Schizophyllum Jehol 70.00 m
8. Gray-green tuffaceous gravel coarse sandstone, mixed with tuffaceous siltstone and limestone. Bivalves: mollusca spirea, A.cf.quadrata, Nakamaranaia cf.subrotunda, N.sp；; Gastropoda: Prouropoda, Valvata sp. See cf.laevis； for brain gyrus; Ostracoda: ACIPENSER sinensis, ACIPENSER sinensis, juvenile Lycophagus carpio, Balabinski 1 1. 18m.
7. The lower part is gray-green calcareous shale mixed with marl and fine sandstone; The upper part is tuffaceous coarse sandstone with silty mudstone. Bivalves: soft-shelled algae from Lingyuan, soft-shelled algae from Estonia and soft-shelled algae from Nakamura. ; Gastropoda; Gastropoda; ; Arachnida: eosensteria (difomograpta) cf. ovata, e. (e. (d.) cf. gongyingziensis; ; Ostracoda: Darwinula barabinskensis, Mongolianella longula, Luan pin-gella dorscinva, Yanshanina dabeigouensis, Djungarica Camarata (= Mongolian ella Khamarininesis); Plant: equisetum.
6. Gray-green and gray-white silty mudstone mixed with fine sandstone and calcareous sandstone. Fish production: Lycopodium? ; Bivalves: subcentral snakehead, Siberian snakehead, short-tailed snakehead, Tommy snakehead and pointed-tailed snakehead. ; Gastropoda: Warva Tower, v.sp. ; Arachidae: eoestheria(diformagrapta)gibba, E.(D.)cf.ovata, E.(D.)minor, Yanjiestheria (yanshania) dabeigouensis, y. (y.) subquadrata; Ostracoda: Dabeigou CYPRINIDAE, Dabeigou CYPRINIDAE, Yumenia CYPRINIDAE, Dabaimei CYPRINIDAE, Dabaimei CYPRINIDAE, Dabaimei CYPRINIDAE, Longbaimei CYPRINIDAE, Xiaobaimei CYPRINIDAE; ; Plant: equisetum. 33.76 meters.
5. Dark purple thick layer, composed of coarse sandstone, siltstone and silty shale, with a thickness of 38.95 meters.
Dabeigou Formation:
4. Brown green and brown yellow tuffaceous coarse sandstone, gravelly coarse sandstone mixed with argillaceous siltstone12.75m.
3. The lower part is gray-green tuffaceous gravelly coarse sandstone, the middle-upper part is tuffaceous fine sandstone and siltstone, and the top part is green mudstone15.70m.
2. Gray-green shale and siltstone mixed with argillaceous crystalline limestone and rhyolitic crystalline tuff. Phyllostachys pubescens: wood moth; ; Ostracoda: Luanpingella postaeuta, Mongolian subclass-animal subclass; ; Plant: equisetum. 50.50 meters
1. light gray, gray-green silty claystone mixed with gray coarse sandstone, fine sandstone and marl 40.488+00 m.
inconformity
Zhangjiakou Formation in the underlying stratum: brownish purple and grayish green coarse-grained tuff.
In the above profile, the overlying stratum Watermelon Garden is generally considered as the sedimentary interlayer of Yixian Formation (Huajiying Formation), which is called Watermelon Garden Formation in northern Hebei. According to Liu Yongqing, the two layers of andesite in Watermelon Garden are intermediate-basic volcanic rocks with horizon significance.
In order to unify the stratigraphic units in northern Hebei and western Liaoning, the Watermelon Garden Formation is called the Watermelon Garden Layer of Yixian Formation. The sedimentary strata in Dabeigou Formation in a broad sense are equivalent to the original "Dadian Subgroup" and named as "Dadian Sublayer of Yixian Formation".
The Dadian sublayer and Dabeigou Formation of Yixian Formation are both sedimentary strata, which are generally called Dabeigou Formation in a broad sense. However, there are coarse clastic deposits at the bottom of Dadian sublayer, which is the beginning of a new sedimentary cycle. The narrow Dabeigou Formation is deposited below, which is developed in other basins in northern Hebei except Luanping Basin. Therefore, the "Dabeigou Formation" in this paper refers to the Dabeigou Formation in a narrow sense.
Dabeigou Formation is missing in western Liaoning. The lower part of Dadian sub-layer (section 1 ~ 2) can be compared with Laogonggou layer, Yenangou layer of Yixian formation in Yixian area and Lujiatun layer and subsoil laigou layer in Sihetun area of Beipiao. Dabeigou Formation constitutes the main body of Dabeigou Stage, so the boundary between Dabeigou Formation and Dadian Sub-layer is the boundary between Dabeigou Stage and Yixian Stage, and it is also the boundary stratotype of Yixian Stage.