Remote sensing geology

The remote sensing image map used in this project is compiled from TM image data and aerial photos. It was completed by the Navigation Telemetry Center of China Geological Survey using1:500,000,1:250,000 and1:50,000 TM false color composite (7, 4 and 3 bands) images and aerial photos respectively. 1:50000 TM pseudo-color composite image (7, 4 and 3 bands) has a large color difference, and the geological body images in different regions are obviously different, which is very helpful for the interpretation of strata and rock masses. The1:50,000 aerial photograph has relatively small chromatic aberration, but high definition, and the linear image is very obvious, which is also conducive to the interpretation of faults and fold structures. Generally speaking, the survey area belongs to a region with high degree of remote sensing interpretation, with clear information such as rock outcrops, geological structures and mineralization zones, high resolution, high clarity and large amount of information, which can completely meet the requirements of1:50,000 mineral resources survey.

(1) image layer

According to the color, tone, geomorphological features and schlieren features of the image, we can not only delineate strata and rock masses in different times, but also distinguish Quaternary sediments with different origins. For example, the Neoarchean-Paleoproterozoic Dunhuang Group ((Ar2-Pt1) D.): The image is light red-dark brown, with banded and striped features, reflecting the characteristics of a set of deep metamorphic rocks (crystalline schist, gneiss and plagioclase amphibole), and the terrain is relatively flat. The ancient caverns of the Great Wall system (ChG. ): It is light grayish green to light blue, with light brown stripes, and the roughness is relatively large. It reflects the characteristics of a set of medium-deep metamorphic rock series composed of crystalline schist, marble-bearing granulite and magnetite quartzite, with relatively gentle terrain and developed dendritic water system. Pingtoushan Formation (Jxp) in Jixian system: blue-gray, dark-gray-black stripes, which are the characteristic reflection of a set of shallow metamorphic rocks dominated by metamorphic carbonate rocks and metamorphic clastic rocks. Topographically, it is a relatively high mountain range with parallel water systems. Qingbaikou Dahuoluoshan Formation (Qnd): It is divided into two subgroups: Upper subgroup (Qnd2) is dark blue-gray tone, dark gray-dark green gray parallel stripes, steep mountain terrain and dendritic water system; The lower sub-group (Qnd 1) is a light blue color band, with a light pink tone, relatively uniform tone and well-developed dendritic water system, which is a characteristic reflection of a set of shallow metamorphic rocks (metamorphic carbonate rocks mixed with metamorphic clastic rocks, metamorphic feldspar sandstone, etc.). ). Sinian Xichangjing Group (ZX): dark brown-gray, which is the characteristic reflection of a set of shallow metamorphic clastic rocks. Generally, small mountain landforms, radial and dendritic water systems are formed. Cambrian: Shuangyingshan Formation () of Lower Cambrian is dark blue-light blue with dark blue-gray stripes, reflecting the characteristics of a set of carbonate rocks mixed with fine clastic rocks and clastic rocks. This is a relatively high mountainous terrain with a developed dendritic water system. The Xishuangyingshan Formation () of the Middle-Upper Cambrian is light blue-light blue-green, with dark blue-gray stripes, which is a set of characteristic reflections of carbonate rocks mixed with fine clastic rocks and clastic rocks, forming relatively gentle slopes and hills, and developing dendritic water system. The Ordovician Luoyachushan Formation (Ol) is a dark blue tone with brownish gray parallel stripes, which is a set of characteristics of clastic rocks mixed with carbonate rocks, forming high mountains and developing parallel-dendritic water system. Silurian Gongpoquan Formation (S2-3g): pink, red stripes or patches with meat, which is a set of characteristics of clastic rocks, volcanic rocks and pyroclastic rocks. The terrain is relatively flat and the dendritic water system is developed. Devonian: ① Sanjing Formation (D2s): It is a reddish-brown block with brown tone, which is relatively uniform, reflecting the characteristics of clastic rocks, volcanic rocks, pyroclastic rocks and carbonate rocks, with high terrain and dendritic water system. ② Dundunshan Group (D3d) is dark gray-dark gray green with reddish brown stripes, which reflects the characteristics of pyroclastic rocks, breccia lava and volcanic lava. Rough, alpine landform, dendritic water system is extremely developed. Permian: ① Hongyanjing Formation (P2hn): It is mainly light pink with light gray and maroon blocks, which is the characteristic reflection of clastic rocks with shale and siliceous marl, with flat terrain and dendritic water system. ② Zhesi Formation (P 1z): it is mainly yellowish brown and red block, which is a set of characteristic reflections of biological limestone, argillaceous limestone and clastic rock. Topographically, it is a low ridge with a dendritic water system. Neogene Pliocene Kuquan Formation (N2k): bluish-gray, slightly light pink, with uniform tone, which is the characteristic reflection of clastic rocks and fine clastic rocks. The terrain is relatively flat and the dendritic water system is developed. Quaternary: The color of the image is mixed, which is generally related to the weathering of the original rock stratum. The main colors are light blue, dark blue, yellow-green, pink and yellow-white, which are the characteristics of alluvial and diluvial debris. Topographically, it is mainly composed of alluvial fans, gullies, valleys and alluvial plains.

(2) Image intruders

Because of its high light mineral content and high brightness, the intermediate-acid intrusive rocks are characterized by light red tone, and the terrain is gentle and low mountains. Basic ultrabasic rocks are characterized by high dark mineral content and low brightness, dark red pig liver color, hills and ridges, and strong weathering resistance.

(3) Image structure

1. Linear image fault structure

The linear image structure of the survey area is very obvious. There are four groups on the image map: near east, northwest, northeast and north and south, and the two groups are mainly near east and northwest. Generally, it is a narrow light shadow pattern, and dark shadow patterns (which may fill dikes) are distributed continuously, and the geological bodies on both sides are obviously different, which is the image performance of major regional faults.

(1) Near East-West Structure

The east-west (nearly east-west) linear image is dominated by regional large faults, which are distributed on the north and south sides of Yingmaotuo Huoshi Mountain and Shajingzi Dajiaorui-Kaoko Jiaorui area.

The spatial distribution of two regional large faults on the north and south sides of Huoshi Mountain is an arc protruding to the south, and the terrain is negative. The rock shadows and linear structures on both sides of the fault zone are obviously different. The northern Hargentou Bubu fault in Huoshishan runs from west to east, and its trace changes from northwest to near east. The western section is obviously gully, which is extremely out of harmony with the NE-trending linear line on the north side, while the eastern section is in and out, and intermediate-acid intrusions are exposed along the north side of the fault. The main body of the southern segment of Huoshishan fault is covered by Quaternary, which is a nearly east-west gully along the fault zone and has a seasonal water system.

The Nandajiaorui-Kaokejiaorui area of Shajingzi sheet presents a graben-like image pattern with nearly east-west positive and negative topography, and the fault image features are clear. The Heishan-Shuangyingshan fault, which is distributed along the line from No.3 mining area to No.5 mining area in Hongshan Iron Mine in the north, is formed by "welding" granite, but the obvious difference of stratum occurrence between the north and the south reflects the characteristics of regional large faults. On the south and north sides of the east-west banded horst in the middle and south, besides different rock image models, fault triangles and fault cliffs of a certain scale can be seen, which is the image reflection of regional fault structures.

(2) NW-trending fault structure

The NW linear images are distributed in the northeast of Shajingzi and the southeast of Yingmaotuo, mainly small-scale NW linear images, forming a tone interface of different geological bodies, and the colors, patterns and occurrences of rock images on both sides of the interface are different. There are diabase walls, dikes and granite plants along this group of faults.

(3) North-South fault structure

The north-south linear images are distributed in the southeast of Yingmaotuo and the northeast of Shajingzi, which are a group of linear images and dark zones. The former usually makes the geological bodies on both sides obviously staggered, while the latter is mostly dike rocks (diorite or gabbro) filled along the fault.

(4) NE structure

NE-oriented linear images are distributed in Huoshi Shanxi and Hongshan Iron Mine No.3-5. The northeast linear structure of Huoshishan is mainly characterized by two tones and two styles of interfaces, and the Silurian strata are cut into a diamond-shaped block with two NW-trending faults. The rhombic block is in sharp contrast with the surrounding brownish-red dense-branched reticular geological body. The linear structure in the west of the fifth mining area of Hongshan Iron Mine is mainly a group of nearly parallel light and dark bands. The former is mostly gullies with staggered or obviously displaced rocks on both sides, while the latter is mostly dikes (diorite or gabbro) filled along faults.

2. Image folding structure

In the survey area, two anticlines and syncline structures are explained from the image, one is the manhole anticline in the middle of Shajingzi and the other is the eastern syncline of flint in the middle of Yingmaotuo, and the image fold structure is clear. Geological bodies with different tones form symmetrical repetitions on both sides of the fold axis, and closed ends can be seen.

3. Image ring structure

This image structure is undeveloped, and only a ring structure is explained in the Ordovician Luoyachushan Formation about 2km south of Yingmaotuo Spring in the southwest corner of Yingmaotuo Sheet, and pseudo-color synthesis is carried out in1:50000 tm (zones 7, 4 and 3). The image on the map is an elliptical ring image of the northwest axis, which is about 3km long from east to west and 2km wide from north to south. The white stripe image is the core, and the periphery is gray-black and gray-brown ring images. On the aerial image of 1:50000, the patterns in the circular image are even, banded and light in color. The peripheral patterns are reticulate or patchy, and the color is dark. A discontinuous semicircle water system is formed between them, which is presumed to be caused by concealed rock mass.

4. Transfer relationship of image structure

It can be seen that the NW-oriented image structure is mainly confined to the north and south sides of the EW-oriented image structure, but not obvious on the outside, indicating that the NW-oriented structure was formed in the left-lateral strike-slip period of the EW-oriented shadow structure, that is, later than the EW-oriented structure.