Figure 3-3-5 Distribution Map of Yixian Formation in Lingyuan-Pingquan Basin
Yixian formation can be divided into three units: the lower intermediate-acid volcanic rock layer, which is distributed in the central and western parts of the basin; Daxinfangzi layer in the middle and intermediate-acid volcanic rock layer in the upper are distributed in the east of the basin, and there are two sedimentary layers in the upper unit. Tuchengzi Formation is mainly distributed in the south of Sanjiazi and Yang Shuling-Weizhangzi area, while Zhangjiakou Formation is distributed in the east of Sanjiazi and the north and east of Weizhangzi.
The basin can be divided into Sanjiazi area of Lingyuan in the east and Pingquan area in the west. Lingyuan-Sanjiazi area starts from Daxinjia in Xiaochengzi Township in the north and passes through Songzhangzi and Liuhaigou to Sanjiazi area in the south. The west side belongs to Pingquan area of Hebei Province. Jiufotang Formation in Wafangdian and Beilu areas on the east side is covered by Yixian Formation. It is distributed from Zhuanghugou to Dongshan Forest Farm to the east of Sanjiazi. The lower part of Yixian Formation is missing, and the middle and upper parts are directly unconformity on alkaline volcanic rocks and pyroclastic rocks of Zhangjiakou Formation.
Yixian Formation in Pingquan area is mainly distributed in the vast area from loess Liangzi in the north of Pingquan County to Songzhangzi and Weizhangzi in Lingyuan, Liaoning Province, and the angle is not integrated in Zhangjiakou Formation and Tuchengzi Formation. The suspicious Jiufotang Formation in this area is only found near Luozhangzi.
(a) The upper part of Shuiquangou-Dongjiagou Yixian Formation in Wangzhangzi, Lingyuan and the middle part of Maozishan Yixian Formation in Sanjiazi Town, Lingyuan (Figure 3-3-6, modified according to Hebei/KLOC-0: 50,000 scale report)
Figure 3-3-6 Cross-sectional view of the upper route of Shuiquangou-Dongjiagou Yixian Formation, Dawangzhangzi, Lingyuan
Overburden: conglomerate of Jiufotang Formation.
inconformity
The total thickness of the upper part of Yixian Formation is 994.90 meters.
Intermediate-acid volcanic rocks (10) are173.50m thick.
10. purplish gray dacite173.50m.
The west (9) floor of the bungalow is 60.50m thick.
9. The purplish red composite conglomerate is 60.50m.
Intermediate-acid volcanic rocks (8 ~ 4) are 760.90 meters thick.
8. The purplish red dacite volcanic breccia is 65.22 meters high.
7. purplish gray dacite173.92m.
6. Purple dacite breccia 152.438+08m
5. Purple rough dacite 217.40m.
4. Grey purple dacite tuff breccia 152.438+08m
-Faults
3. Daxin House Floor (fault cutting, thickness unknown)
Incomplete integration
Zhangjiakou group
Bottom: Lower member of Yixian Formation in Maozishan, Sanjiazi Town, Lingyuan (Figure 3-3-7, modified according to Hebei1:50,000 report).
Figure 3-3-7 Middle Section of Yixian Formation in Maozishan, Sanjiazi Town, Lingyuan
Yixian formation in central China
Daxinfangzi Floor (34 ~ 2): 225.48m thick.
34. Light gray purple thick tuffaceous conglomerate, which is composed of andesite and dacite, has a maximum of 30×4 cm2 and a minimum of 2×6 cm2, with high roundness and poor sorting. The filler is tuff16.09m.
33. The grey pore almond andesite is 9.26 meters.
32. Gray-purple tuffaceous conglomerate, composed of andesite, 2×6 cm2, with good roundness and poor sorting, with gravel accounting for 60%, and the interstitial material is tuffaceous16.09m.
3 1. grayish purple tuffaceous conglomerate, composed of andesite, 30×40 cm2, with good roundness and poor sorting, with a content of 70% 3.80 m.
30. Gray-purple tuffaceous breccia1.09m.
29. Grayish white gravelly tuffaceous sandstone, containing 65,438+05% gravels and 65% cuttings, is composed of andesite and 8. 15 m tuffaceous filler.
28. Gray tuffaceous conglomerate, composed of andesite, 30×40 cm2, well rounded and poorly sorted, with a content of 40%, and the interstitial material is tuffaceous1.63 m..
27. Gray tuffaceous fine conglomerate, composed of andesite gravel 1×2 cm2, is well rounded and poorly sorted, with a content of 65%, and the interstitial material is tuffaceous14.66m.. ..
26. Gray tuffaceous conglomerate, the gravel is andesite, generally 5×6 cm2, with gravel content of 60%, and the interstitial material is tuffaceous 2.32m. ..
25. Gray-white gravelly tuffaceous sandstone, with cuttings content of 60% and gravel content of 40%. The interstitial material is tuffaceous 4.65m..
24. Gray-white tuffaceous conglomerate, composed of amphibolite andesite, contains boulder, 30×40 cm2, with content of 60%, and the interstitial material is tuffaceous1.16 m..
23. Gray tuffaceous conglomerate, composed of andesite, with a size of 4×6 cm2 and a circular shape, with a content of 60%. The filler is tuff 1. 16m. ..
22. Gray gravelly tuffaceous sandstone, with gravel size of 40×30 cm2 and content of 10%, is well rounded, with cuttings content of 70%10.95m.. ..
2 1. Gray-purple tuffaceous conglomerate, composed of dacite and andesite, has a maximum of 20×40 cm2 and a minimum of 3×4 cm2, with high roundness and poor sorting, and the filling material is tuffaceous 4.94 m.
20. Grayish purple tuffaceous siltstone, thin-bedded, with horizontal bedding development1.4438+0 m.
19. Gray-green tuffaceous siltstone, horizontal bedding, thin layer, containing mesophyll (poorly preserved, unable to identify varieties) 4.07m..
18. Grayish white and gray mudstone interbedded with tuffaceous sandstone, mudstone is textured, see detachment structure. Eosestheria spp. and insect fossils (not well preserved, species not identified) 4.58m.
17. The interbedding of tuffaceous sandstone and mudstone from gray and grayish white thin layer to middle layer is 3.10 m.
16. Gray-green thin mudstone with inclusion structure. Phylogenesis: eosestheria sp .0.44 m.
15. Gray and grayish white tuffaceous sandstone and mudstone interbedded1.33m.
14. Gray tuffaceous sandstone with thin layer and horizontal bedding of 6.20m.
13. grayish green tuffaceous siltstone 2.95m.
12. The bottom is 15 grayish yellow tuffaceous siltstone, the top is grayish yellow tuffaceous fine sandstone, and the top is 1.5 m grayish white siltstone, 5.40 m.
1 1. Light gray silty shale and argillaceous shale interbedded, with rhythm development. Sporopollen products: Pinaceae, pre-fertility, Picea, Picea, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus, Pinus. Ostracoda; Cyprinidae Indet (intima), Lycopterocypris infantili is lubimova (intima), L.sp (intima), Darwinula sp.indet (intima)10.80m.
10. Light gray tuffaceous sandstone, siltstone and 10.98m interbedded.
9. Light gray and light gray silty shale interbedded to produce mesophyll. ; Wolf fish and insect fossils (unknown species)16.30m.
8. Yellow-green and grayish-yellow tuffaceous siltstone, producing pollen of Pinaceae, Protopine, Picea, Pseudopine, Pinuspollenites, Podocarpidites, Pristinuspollenitens, Pseudowalchia, Perinopollenites, Psophosphaera and Aralcariacites.
7. Grayish yellow gravelly tuffaceous coarse sandstone, composed of andesite, with contents of 10% and 1cm2, with tuffaceous cementation of 0.99m m.
6. Gray and grayish yellow tuffaceous fine sandstone with horizontal bedding development of 2.65m.
5. Gray-purple tuffaceous fine sandstone with horizontal bedding of 33.54m.
4. Gray-purple and gray massive tuffaceous conglomerate, with the gravel size of 20×30 cm2 and composition of andesite and tuff, with poor sorting and roundness of 2.83 m.
3. Grayish purple tuffaceous fine-grained lithic sandstone1.42m.
2. Gray-purple andesite conglomerate, with the size of 10×2 cm2, high roundness and poor sorting. The interstitial materials are sandy and tuff11.33m. ..
Incomplete integration
Underlying stratum: gray-purple andesite breccia lava of Zhangjiakou Formation.
Next step: the section from Zhangzi Shuiquangou, Dawang, Lingyuan to Yixian Formation, Dongjiagou (Figure 3-3-6)
Zhangjiakou Group:
2. Grayish white and purplish red siltstone, sandstone, glutenite and conglomerate are rhythmically interbedded with grayish purple dacite volcanic breccia and 286.62m grayish green dacite lava, with rhyolitic giant breccia in between.
1. Gray-green and purple-gray dacite breccia lava137.92m.
(2) lingyuan city Fanzhangzi-Fangping Yixian Formation Upper Route Profile and lingyuan city Dawangzhangzi-Fanzhangzi-Shanzui Yixian Formation Lower Daxinfangzi Layer Grass Survey Profile (Figure 3-3-8).
Figure 3-3-8 Cross-sectional view of the upper route of Fanzhangzi-Fangping Yixian Formation in Lingyuan.
Overburden: No roof is found (Quaternary overburden).
The total thickness of the upper part of Yixian Formation is > 493.29 meters.
The thickness of intermediate-acid volcanic rocks (1 1) is more than 40m.
1 1. Moderately acidic volcanic rocks > 40m.
Pingxi Room (10) is 68.30 m thick.
10. Gray-green tuffaceous sandstone, glutenite and fine conglomerate 68.30m.
The intermediate-acidic basic volcanic rocks (9 ~ 5) are 2 18.85 meters thick.
9. Purple-gray and gray-green dacite breccia is 45.46m.
8. Purple-gray dacite 68.19m
7. Gray-black olivine basalt15.00m.
6. Gray-green almond-shaped andesite 43.70 meters.
5. Purple-gray dacite is 46.50m.
Dadonggou Layer (4) is thick136.38m..
4. The purplish gray sedimentary pyroclastic rocks are intercalated with tuffaceous limestone and purplish red gravelly siltstone (136.38 m).
3. Black basaltic porphyrite intrusion
Intermediate-acid volcanic rocks are 292.76 meters thick.
2. Purple-gray dacite is 272.76m.
1. purplish gray volcanic breccia 20.00m.
Not bottomed out
Next: Sketch profile of Daxinfangzi layer of Dawangzhangzi-Fanzhangzi-Yixian Formation in Lingyuan (Wang Xiaolin et al., 2000).
Superimposed: Late volcanic rocks
Yixian formation in central China
Daxin house thickness 150 ~ 200m.
7. Gray-green and gray tuff gravelly coarse sandstone-gray tuff 70 ~ 80 m.
6. Gray-gray-black-gray-white shale mixed with yellow-brown and yellow-green tuff, containing fish: Lycopodium, Peipiaosteus pani, Protopsephurus liui ui, Yanosteus longidorsalis；; Reptiles: Leptosaurus, Pterosaur Lingyan, Pterosaur gracilis, Pterosauroidea. 1 1 month, sauropod, Millennium Chinese bird dragon. ; Mammals: Jaholodens Jenkins; ; Birds: grouse, grouse; ; Insects: Three-petaled Mayfly, Gall Mosquito; ; Arachidae: Paraliograpta sp. , Eosestheria sp. Harmonia ovata. ; Plants: equisetum lineatum, equisetum longipedunculata, Pteris japonica, Prunus mume, Pteris japonica, Fraxinus ash, Iris lactuca, Aralia elata, Aralia elata, Aralia angustifolia, Datura angustifolia, Datura densiflora, Zizyphus jujuba, and Sonchus. ，Brachyphyllumsp。 , Liaoning oak, long-handled flower, stair grass with pinnate leaves, stair grass with slender stems, ephedra, Liquidambar formosana, etc. 5 ~ 8m。
5. Gray-green coarse-grained tuff, tuffaceous sandstone-fine-grained tuff, consisting of 3-4 small cycles12 m..
4. Gray purple and gray tuff, with obvious rhythm, with horizontal and deformed bedding of 2 ~ 3m.
3. Gray conglomerate, mainly pyroclastic rock, sub-circular, moderately sorted, 2 ~ 4m.
2. Gray-green coarse tuff, gray and gray-black siltstone, shale mixed with gray-white and tawny tuff. The shale contains arachnid: Eosestheria sp., insect: ephemera, plant fossil16 m.
1. Volcanic breccia-tuffaceous glutenite and gravelly tuffaceous coarse sandstone. Gravel is mainly composed of volcanic rocks, with angular and sub-angular features, poor sorting, obvious rhythm and horizontal or oblique bedding > 20 m.
integrate
Underlying stratum: intermediate-acid pyroclastic rocks in the lower part of Yixian Formation.
(3) Lower member of Liuhaigou Yixian Formation, Sandaoyingzi-Dawangzhangzi, Lingyuan Yushu, Pingquan (Figure 3-3-9, modified according to the geological report of Hebei District 1968,1:50,000 Songzhangzi and 30 hippopotamus chefs).
Figure 3-3-9 Lower Member of Yixian Formation in Liuhaigou, Dawangzhangzi, Lingyuan, Sandaozizi, Yushu and Pingquan.
Overburden: Late coarse andesite intrusion.
Lower part of Yixian Formation
Medium-acidic coarse andesite volcanic layer (50 ~ 1): thickness 17 19. 18 m.
50. light grayish yellow andesite breccia, accounting for 30% ~ 40%, containing a small amount of rocks, 34.84 m.
49. Light grayish yellow andesite breccia with a layer of 6.85m thick layered rhyolite tuff.
48. Grey andesite aggregate breccia, containing 40% breccia and 10% 37.6438+06m aggregate.
47. The mixed size of taupe andesite lumps is as high as 70%136.05 m.
46. Light taupe coarse andesite breccia10.47m.
45. Grey brown coarse andesite breccia lava 31.34m.
44. The lava of taupe andesite breccia is 41.45m.
43. Light gray andesite volcanic breccia is 24.64m.
42. Gray andesite breccia lava18.70m.
4 1. Gray and grayish yellow andesite volcanic breccia+07.8+0m. 56686.88868888666
40. The gray coarse andesite breccia lava is 32.98m.
39. Gray-black andesite breccia lava 31.95m.
38. Gray-black coarse andesite10.65m.
37. The taupe andesite breccia lava is 20.50m.
36. The taupe dacite is 52.55 meters.
35. The gray-purple coarse-grained dacite with breccia is 9.44 ~ 25.338+0 m.
34. Grey purple dacite aggregate, the largest aggregate is 1 m, with a content of 40%. Some aggregates are black rough dacite, and some are red brown dacite 3.16 m.
33. Grey-yellow dacite aggregate, the aggregate content is 30% ~ 40%, and the aggregate is above 1 m and above 8.15 m.
32. The grayish brown dacite breccia is 4.66 meters.
3 1. grayish black silicified coarse andesite, containing breccia 10% ~ 15% and cuttings of 0.48m.
30. The gray-yellow dacite breccia is 4.08 meters.
29. Gray-green dacite volcanic breccia 2.76m.
28. Gray-green dacite volcanic aggregate, with aggregate accounting for 30% ~ 40% and breccia accounting for10% 4.66 m.
27. Gray-black dacite breccia aggregate, which is aphanitic dacite, accounting for 60% ~ 80% of 55.27 m.
26. Gray-green and gray-brown chloritization dacite volcanic breccia consists of 65% breccia, 25% cuttings, 10% cement and a small amount of crystal fragments. It can be seen that a small number of volcanic bombs are ellipsoid13.78 m.
25. Gray-green, yellow-brown dacite breccia tuff, with breccia accounting for 20% ~ 30%, and the rest being 0.92m cuttings and microcrystals.
24. The taupe dacite breccia is 4.22 meters thick.
23. Gray-green dacite tuff 1.5438+0 m
22. Gray-green dacite fire breccia, breccia < < 4 cm, content 40% ~ 50%1.39m.
2 1. Gray-green dacite tuff is 23.26m..
20. The gray-green dacite tuff with breccia is 70.66 meters.
19. Gray rough andesite containing breccia pyroxene, with porphyritic plagioclase accounting for 10% ~ 15%, potash feldspar and plagioclase accounting for 70% ~ 75%, with red top and green bottom, among which 6 eruptions were 83.79 m.
18. Gray rough andesite containing breccia pyroxene, in which feldspar accounts for 15% of pyroxene and 10% ~ 15% of phenocryst, and the matrix is potash feldspar, plagioclase and dark minerals, accounting for 70% and 7.15% respectively.
17. Gray-green chloritization andesite tuff, containing breccia, with breccia accounting for 10% ~ 15%, cuttings accounting for 80%, crystal chips and glass chips accounting for 5%, and cement accounting for 16. 18m.
16. black glass-based erhui dacite 6.34m.
15. Gray-green chloritization andesite tuff, containing breccia, with breccia accounting for 35% ~ 40%, cuttings accounting for 50% and cement pozzolan accounting for10% 23.62 m.
14. grayish yellow and grayish green andesite, with porous almond-shaped structure at the top, and the almond body is 26.28m siliceous.
13. Light yellow almond-shaped glassy andesite, with plagioclase 15% as phenocryst and 3% ~ 5% as augite, with plagioclase, a small amount of augite and vitreous as matrix. The development of stomata and almond structure is 2.56 meters.
12. grayish yellow pyroxene andesite, feldspar and Labrador phenocrysts account for 20% ~ 25%, pyroxene accounts for 5% ~ 10%, and matrix accounts for 70%. Red top and green bottom developed, including 34 eruptions of134.5438+09 m.
1 1. Gray pyroxene andesite mixed with yellow stomatal andesite, with 20% ~ 25% feldspar in phenocryst, 60% ~ 70% matrix, almond-shaped structure of stomata, and strong red top phenomenon, with 20 eruptions130.40.
10. Gray andesite with red roof, with 10 eruption,105.27m.
9. Gray-yellow and gray-green porous almond-shaped porphyritic andesite, with phenocrysts containing 40% feldspar and 10% pyroxene, and the matrix being 50% plagioclase, glass and iron. Including 12 eruptions,15438+08.438+0 m.
8. Grey andesite is mixed with purplish red strongly broken glass-based andesite, in which feldspar accounts for 65,438+05% ~ 20%, pyroxene accounts for 5% ~ 65,438+00%, and the matrix is plagioclase and glass accounting for 75%. Including 24 eruptions,153.68m.
7. Grayish yellow tuff breccia of timely andesite, with 55% of timely andesite and andesite, 20% of detritus 15% ~ 20% of crystalline detritus, and 36.79 m of volcanic ash10%.
6. Tuff tuff of Kaqi 'anshan, containing breccia < 5%, cuttings 55%, cuttings 20%, volcanic ash 10. 16m.
5. khaki andesite aggregate breccia, with aggregate accounting for 10% and breccia accounting for 30% ~ 50% 2.38m.
4. Grey brown and gray coarse andesite, containing breccia, plagioclase (feldspar and Labrador) 40%, pyroxene 10% and matrix 50%. The stomatal structure of almond is very developed. Including 1 1 eruption, 86.19 m.
3. Grey yellow coarse andesite aggregate breccia, 10%, 50% ~ 60%.
2. Gray-green coarse andesite aggregate breccia, with aggregate < 10% and breccia 40%. Now chloritization image10.92m.
1. grayish green coarse andesite breccia, see spherical volcanic bomb14 ~17.438+0 m.
Bottom: intrusion of rough porphyry subvolcanic rocks, without bottom.
According to the above profile, in Maozishan area east of Sanjiazi, the lower part of Yixian Formation is undeveloped and directly overlaps with Zhangjiakou Formation. Zhangjiakou formation is missing in the north; Intermediate-acid volcanic rocks are developed in the lower part of Liuhaigou Yixian Formation in Songzhangzi Township, Pingquan, but the top and bottom are invaded by late subvolcanic rocks, and the contact relationship is unclear. In addition, the volcanic structure is unknown, so the thickness is likely to be inaccurate. Fanzhangzi Xishan (Daxinfangzi layer containing rare animal and plant fossils) has a small amount of intermediate-acid volcanic rocks in the lower part of Yixian Formation, which belongs to the lower part of Yixian Formation. There are two sedimentary layers in the intermediate-acid volcanic rock series in the upper part of Yixian Formation, namely Dadonggou layer and Pingfangxi layer.
(4) Profile of Guanfenliang-Daiwangshan Yixian Formation in Pingquan (according to 1999 and1∶ 50,000 geological reports in Hebei)
Bujianding
The total thickness of the lower part of Yixian Formation is1727.06m.
Thick andesite volcanic rocks (69 ~ 62) are 323.36 meters thick.
69. The gray coarse andesite breccia tuff is 39.6 meters.
68. Gray thick layered tuffaceous conglomerate, 3.2m thick.
67. Gray coarse andesite volcanic breccia 51.4m.
66. The gray coarse andesite volcanic breccia is 62.9 meters.
65. Gray purple-gray white coarse andesite volcanic breccia 9.0m
64. The volcanic breccia precipitated by gray-purple coarse andesite is 86.6 meters.
63. Gray purple limonite coarse andesite volcanic breccia12.3m.
62. The grey coarse andesite breccia tuff is 58.3m thick.
Andesite (6 1 ~ 56) is 531.20m thick.
6 1. It consists of 8 flow units, the lower part is gray dense massive andesite, the upper part is purple andesite or andesite breccia lava, and the 2.3 m place near the crater is massive breccia lava.
60. The gray-green andesite subsidence block breccia is 2.3 m.
59. It consists of four lower gray-green pores-almond andesite, middle dark gray almond andesite and upper purple pore andesite. The pores in the lower part are small and scarce, partially filled with chlorite, and the pores in the upper part are large and flat, not completely filled with silica, and are in the middle. The andesite breccia lava developed at the top of some flow units is > 201.1m.
58. It consists of four lower dark gray almond-shaped andesite and upper purple pore-almond-shaped andesite, with a small amount of andesite aggregate breccia lava at the top of 67.3 meters.
57. It consists of five flow units consisting of almond-shaped andesite with gray-green lower part and purple upper part. The pores at the lower part of each flow unit are small and round and filled with chlorite. There are many dense pores in the upper part, filled with silica190.2 m.
56. It consists of four flow units, the lower part of which is gray and the upper part is purple, and it is composed of stomatal andesite. The pores are lenticular, and the streamline and stream surface structure in the rock develop 68.0 m.
Guanfen beam layer (55 ~ 26) is 872.50 m thick.
55. Gray-green coarse andesite breccia tuff 69.1m.
54. Gray coarse andesite tuff is 4.2m..
53. Gray-green coarse andesite breccia tuff is 20.5m..
52. Gray-green tuffaceous sandstone is 8.5m.
5 1 .grayish green coarse andesite breccia tuff 8 1.3 m
50. Gray coarse andesite volcanic breccia 2. 1 m
49. Gray-green coarse andesite tuff is 6.3m..
48. Gray-green coarse andesite breccia tuff 29.2m.
47. Gray-green coarse andesite tuff is 7.6m..
46. Gray-green coarse andesite volcanic breccia12.6m.
45. Gray-green coarse andesite breccia tuff is 2.5m..
44. Gray-green coarse andesite breccia tuff 60.0m.
43. Gray-green coarse andesite volcanic breccia is 42.3m.
42. Dark clouds with light gray amphibole and coarse andesite volcanic breccia are 38.6 meters.
4 1. Gray-green coarse andesite volcanic breccia13.4m.
40. Gray-green tuffaceous sandstone1.7m.
39. The gray-green rough andesite volcanic breccia is 3.4m
38. Gray tuffaceous sandstone1.3m.
37. The gray-green coarse andesite volcanic breccia is 39.6 meters.
36. Purple coarse andesite breccia tuff11.1m.
35. The gray coarse andesite volcanic breccia is 27.7 meters.
34. Light gray pore-almond amphibole coarse andesite 69.0m.
33. The light grayish green conglomerate with coarse andesite is 24.8m.
32. Gray-green coarse andesite accretion breccia18.0m.
30. Light gray purple coarse andesite volcanic breccia
29. Gray coarse andesite volcanic breccia
28. Gray-green tuffaceous sandstone16.8m.
27. Gray green coarse andesite volcanic breccia
26. khaki-grayish green tuffaceous sandstone mixed with silty clay rock
Incomplete integration
Underlying stratum: gray-green chronological coarse andesite volcanic breccia in the second member of Zhangjiakou Formation.
(5) Lower member of Zhangjiayingzi Yixian Formation in Yang Shuling Town, Pingquan County (according to the geological reports of Hebei District 1999 and1∶ 50,000).
Overburden: gray-purple pyroxene coarse andesite volcanic breccia.
merge
Guanfen beam layer (25 ~ 1) is 353.80 m thick.
25. Gray-green chronological coarse andesite breccia tuff with calcareous sandstone.
24. Gray-purple seasonal coarse andesite breccia.
23. Gray chronological coarse andesite volcanic breccia.
22. Gray tuffaceous sandstone mixed with thin tuffaceous siltstone, with positive grain sequence bedding and 23.3m small plate oblique bedding.
2 1. khaki tuffaceous sandstone with good parallel bedding of 5.7m.
20. Light gray silty shale with well-developed foliation produces animal fossils and plant fragments. Insect: Mayfly, Plant: Ginkgo biloba1.3m.
19. khaki tuffaceous fine sandstone1.3m.
18. Blue-gray silty shale with well-developed foliation.
17. khaki sandstone with parallel bedding.
16. Gray thin siltstone, containing a small amount of ginkgo trees.
15. It is composed of khaki gravelly sandstone, sandstone and siltstone, with clear sedimentary rhythm, coarse and fine in each rhythm.
14. light gray chronological coarse andesite accretion breccia.
13. Khaki tuffaceous conglomerate
12. Purple chronological coarse andesite volcanic breccia.
1 1. Light gray tuffaceous gravel sandstone
10. Light gray green tuffaceous conglomerate
9. khaki-grayish green timely coarse andesite breccia aggregate with thin tuffaceous sandstone lens.
8. Khaki tuffaceous sandstone
7. Khaki chronological coarse andesite breccia and thin tuffaceous sandstone lens.
6. Gray-green tuffaceous fine sandstone
5. Gray-green chronological coarse andesite volcanic breccia.
4. Purple chronological coarse andesite volcanic breccia.
3. Gray-green chronological coarse andesite volcanic breccia.
2. Gray-green tuffaceous conglomerate
1. Gray-green tuffaceous fine sandstone mixed with gravelly coarse sandstone
Underwater amphibole black clouds are in contact with coarse andesite intrusion.
Underlying stratum: rhyolitic tuff breccia in the first member of Zhangjiakou Formation.
Yixian Formation in Lingyuan-Pingquan area is widely distributed, and it is a typical volcanic-sedimentary rock series, which is consistent with Yixian Formation in typical section and has similar sedimentary rock interlayer properties. However, the lithologic characteristics of volcanic rock series are different from those of typical profiles, mainly because the volcanic rock assemblage here is mainly intermediate-acid volcanic rocks, lacking basic and intermediate-basic volcanic rocks in Yixian and the lower part of Yixian Formation in Beipiao area.
The stratigraphic framework and filling sequence of Yixian Formation in Lingyuan-Sanjiazi Basin are slightly different in the south and north. In the south of China, Daxinfangzi layer of Yixian Formation directly overlaps with Zhangjiakou Formation. On Shuiquangou-Dongjiagou section, there is a set of intermediate-acid volcanic rock series above Daxinfangzi layer, in which only a thin sedimentary rock interlayer dominated by tuffaceous glutenite is seen. This floor can't be completely compared with the Dadonggou floor in the north or the west building of the bungalow. At the top of the profile, the intermediate-acid volcanic rock layer is covered by the conglomerate layer at the bottom of Jiufotang Formation.
The central and northern part of the basin, from Sandaoyingzi, Yushu Linzi Town, Pingquan County to Liuhaigou, Songzhangzi Township, lingyuan city, and eastward through Fanzhangzi, Dawangzhangzi Township to Fangpingxi, is the main section controlling Yixian Formation. The filling sequence here is based on a set of extremely thick alkaline neutral-intermediate acid volcanic lava, the top and bottom of which are cut off by late intrusive rocks. It is called "Huajiying Formation" by Shijiazhuang Institute of Economics1∶ 50,000 Song Zhangzi Mapping Group (1998). Further up is Daxinfangzi layer, which is rich in rare animal and plant fossils of Jehol biota, mainly composed of a set of lake sediments, and can be used as a marker layer for comparison with Brick City Sub-layer and Beipiao Jianshangou Layer in typical sections. The Dabeigou Formation is missing here. The volcanic rock series above Daxinfangzi layer is a set of intermediate-acid volcanic rock assemblage, with two sedimentary rock interlayers in the middle. The lower part is called Dadonggou layer, and the upper part is Fangpingxi layer, which is mainly composed of coarse clastic tuffaceous conglomerate. Most of the local areas belong to fluvial facies or alluvial fan facies, and there are few fossils. Their horizons are roughly equivalent to Dakangbao and Zhujiagou in the upper part of a typical profile. At the top of this section, there is no direct contact with Jiufotang Formation due to Quaternary overburden, but Jiufotang Formation can be seen not far from Quaternary overburden. Therefore, the Yixian Formation in the north-central part of Lingyuan-Sanjiazi basin can be compared with the Yixian Formation in a typical section except for the lack of basic-intermediate volcanic rocks.
Yixian Formation in Pingquan area is mainly distributed in the east of the line from Pingquan County to Loess Liangzi, and is connected as a whole on both sides of the provincial boundary. In the previous regional adjustment work, the Yixian Formation was artificially divided, with Yixian Formation in the east of the provincial boundary and Huajiying Formation in the west. According to the naming priority rule, Huajiying Formation in northern Hebei, as a post-synonym of Yixian Formation, was abandoned and stopped using.
The Yixian Formation here is represented by the Guanfenliang-Daiwangshan section, with the lower strata of Yixian Formation as the main part. The Guanfenliang layer at the bottom, together with the Zhangjiayingzi section, is similar to Zhangjiakou Formation in rock assemblage analysis, and belongs to the bottom of Yixian Formation temporarily, which needs further study. The top and bottom of Sandaoyingzi-Liuhaigou profile are invaded by coarse andesite, but from its distribution position, it should belong to the lower part of Yixian Formation.
There is a set of neutral volcanic rocks in the middle and lower part of Yixian Formation in this area, with a thickness of more than 800 meters. The upper part of the profile is mainly a set of intermediate-alkaline volcanic rocks. Because the volcano continued to erupt, no sedimentary rock interlayer was found. The sedimentary layer at the bottom of the profile directly overlaps with Zhangjiakou Formation, but overlaps with Tuchengzi Formation in the south of this area, completely missing Dabeigou Formation in the north of Hebei Province. The top of the profile was also interrupted by the intrusion or intrusion of volcanic rocks in the later period, and no direct overburden of Jiufotang Formation was found on it. However, on the east and west sides of Luozhangzi in the north of Pingquan County, there are sediments equivalent to Jiufotang Formation (the fossil assemblage can be confirmed). The west side is superimposed on the acid-base pyroclastic rocks of Zhangjiakou Formation, and the east side is superimposed on the purple gravel of Tuchengzi Formation. The mapping group of Shijiazhuang Institute of Economics (1998) regards Jiufotang Formation here as the product of the same phase as Yixian Formation (the so-called Huajiying Formation in the past), but it should actually be above Yixian Formation. The reason for this new confusion may be the lack of detailed and serious identification and distinction between the two different fossil assemblages contained in the above two groups. Especially in the absence of direct contact, more attention should be paid to the study of biostratigraphy.
In a word, although Yixian Formation here is different from neighboring areas and typical areas in lithologic combination of volcanic rocks and filling sequence of sedimentary rocks, it can still be compared with Lingyuan area.