Granites in this area are mainly distributed in Anziling, Qinhuangdao and Suizhong, including TTG granite, adamellite and potash granite. There is also Jielingkou diorite (Figure 4- 10). In space, they are distributed in a certain band. Diorite and TTG granitic rocks are distributed in the west, while adamellite and potash granite are distributed in the east. In time, diorite and TTG granite were formed in front, and monzogranite and potash granite were formed behind. The following are introduced respectively, and their chemical data are shown in Table 4-3a, B and C respectively.

Table 4-3a Major Element Composition of Archean Granitic Rocks and Episodic Rocks in Eastern Hebei (including Suizhong and Jinxi in Liaoning) (%)

Table 4-3b Trace Element Composition of Archean Granitic Rocks and Episodic Rocks in Eastern Hebei (including Suizhong and Jinxi in Liaoning) (10-6)

Note: The serial number is the same as that in Table 4-3a.

Table 4-3c REE composition of Archean granitic rocks and episodic rocks in eastern Hebei (including Suizhong and Jinxi in Liaoning) (10-6)

Figure 4- 10 Geological Schematic Diagram of Jidong (including Suizhong, Liaoning Province) (slightly increased or decreased according to Lin Qiang et al. (1992))

1- Zhang Zhu subgroup; 2- Shuangshan subgroup; 3- Jielingkou diorite; 4-TTG granitic rocks; 5- adamellite; 6- K granite; 7- Fault

I. Jielingkou diorite

Jielingkou diorite is located in Qinglong-Funing area in eastern Hebei, and it is widely distributed. It is about 34km long from north to south and 14km wide from east to west. On the west side, the rock mass is in intrusive contact with Shuangshanzi Group, which contains supracrustal rocks such as granulite and banded iron ore. The relationship between the east side and Anziling granite complex is unclear. In the area along Shuanglongsi Highway south of Shuangshanzi, it can be seen that the west side of diorite is strongly mylonite, forming hornblende gneiss. Weakly deformed or undeformed diorite blocks remain in the weak strain zone. Because the granite vein inserted into it is also strongly deformed, it can be seen that the deformation occurred after the intrusion of rock mass. The mylonitization zone extends far in the north-south direction. Gneiss in rock mass are generally weak except that the edge of rock mass is affected by late deformation. Fine-grained gabbro and diorite inclusions with different sizes can be seen in the rock mass, which are of different shapes and uneven spatial distribution. The rock is medium-coarse grained. The mineral assemblage is plagioclase, amphibole, biotite and quartz. Automorphic plagioclase and amphibole can also be preserved, showing the characteristics of magmatic structure. The accessory minerals are sphene, zircon, apatite and rutile.

In terms of chemical composition, the analysis results of the two samples are: SiO2: 54.59% ~ 60.36%, TFEO: 6.54% ~ 7.66%, MgO: 2.78% ~ 2.96%, Cao: 5.16% ~ 8./kloc-0. On the AB-AN-OR diagram, they are located in tonalite District (Figure 4- 1 1). The rare earth content in rocks is not high, the separation between light and heavy rare earths is weak, and there is no obvious europium anomaly (Figure 4- 12a). On Pearce diagram, there are negative Nb anomalies and high P content. In addition, the rock also shows the loss of Ba relative to Rb and Th (Figure 4- 13a). The amphibole fine-grained inclusions wrapped in diorite are similar to basaltic rocks in the composition of major elements, but there are rare earth models and pearlite diagrams similar to diorite (Figure 4- 14A and b). The main difference is that Ba element in fine-grained inclusions has no loss compared with Rb and Th. Obviously, they can't be the product of crystallization differentiation of Jielingkou diorite, and Jielingkou diorite can't be formed by their partial melting. According to the geochemical characteristics of rocks, the formation of Jielingkou diorite is probably related to the subduction of ocean plates and overlying sedimentary rocks and the resulting high melting degree. Hornblende fine-grained inclusions are deep materials in the lower crust captured during the rising of diorite magma.

Figure 4- 1 1 Jidong (including Suizhong-Jinxi, Liaoning)

The AB-An-OR diagram of granitic rocks in this area is multiplied by the mark-Jielingkou diorite; Unfilled round-anziling TTG granite; Unfilled square-Anziling granodiorite-adamellite; Unfilled triangular-Shanhaiguan potash granite; Filling ring-Suizhong adamellite; Potassium granite filling in square-Suizhong-Jinxi area; Plus sign-Anziling potash granite; The data of Anziling granite body are mainly quoted from Mu Kemin et al. (1989).

Two. Anziling granite complex

Granitic rocks in Anziling area occur in the form of compound rocks. The building complex is dome-shaped with an exposed area of about 100km2. In the west of the complex, it is in migmatized gradual contact or intrusive contact with Shuangshanzi Group. The Anziling granite complex has undergone great changes in rock types and structures. There are many different types of rocks, such as quartz diorite, granodiorite, adamellite and potash feldspar granite. This change can be shown even in a small outcrop range. Most granites have medium-coarse grained gneiss texture. In some places, there are red microcline phenocrysts, which become typical eyeball gneiss. The metasomatic texture of rock is developed, and there are a large number of interlaced particles composed of synbiotics and two kinds of feldspar, which may be the product of low-degree melting (Mu Kemin et al., 1989). There are often layered, layered, lenticular amphibolite and granulite residues with different sizes in gneiss granite. Some adamellite and potash granites are weakly deformed medium-fine grained granites. They are widely distributed or occur in veins, interspersed with gneiss granitic rocks and various types of supracrustal rocks. The occurrence characteristics of granitic rocks show that they are formed by metasomatism and partial melting of continental crust materials, and their exposure range is roughly equivalent to the original or semi-original position of magma origin.

Fig. 4- 12 rare earth model of granitic rocks in eastern Hebei (including Suizhong-Jinxi, Liaoning)

A— Jielingkou diorite (round) and Anziling TTG granite (triangle); B- Anziling TTG granite (data quoted from Mu Kemin et al.,1989); C— Anziling adamellite (multipliers and triangles connected by solid lines) and Anziling potash granite (circles and squares connected by dotted lines) (data quoted by Mu Kemin et al.,1989); D- Suizhong adamellite and E- Shanhaiguan potash granite (data quoted from Mu Kemin et al.,1989); Potash granite in Suizhong-Jinxi area

Accordingly, the chemical composition of Anziling granite body has also changed greatly. On the AB-An-OR diagram, they are distributed in a large composition range from tonalite to granite (Figure 4- 1 1). The analysis data of us and Mu Kemin et al. (1989) all show that TTG granitic rocks have a rare earth model with strong separation of heavy rare earths, strong loss of heavy rare earths and no obvious negative europium anomaly (fig. 4- 12A and b). Although TTG granitic rocks and Jielingkou diorite have similar element distribution patterns on the pearlite map (Figure 4- 13a), judging from their rare earth compositions, they cannot be related by crystal segregation or partial melting of diorite. This is consistent with the knowledge obtained from the geological occurrence of Anziling complex itself. Sample QS 16-2 has low heavy rare earth loss and high total rare earth content (fig. 4- 12b), which seems to be due to more apatite accessory minerals in the rock. The content of P2O5 in this sample is 0.37% (Mu Kemin et al., 1989). The solid line in Figure 4- 12C shows the rare earth model of adamellite in Anziling complex. Compared with TTG rocks, their total rare earth content is higher, but heavy rare earth is also lacking, and there is no obvious negative europium anomaly. It seems that the rare earth composition of sample Qs50- 1 is also affected by apatite, and its P2O5 is as high as 0.38% (Mu Kemin et al., 1989). This shows that the accessory minerals rich in rare earth have great influence on the rare earth composition of granite rocks, sometimes even greater than the difference between different rock types. The content of rare earth in Anziling potash granite is high and varies greatly, and there is no obvious negative europium anomaly. One of the samples (sample S377- 1 2c in Figure 4) has a high rare earth content (La). The value is as high as 1000, which is obviously related to the existence of accessory minerals. Although Anziling potash granite is rich in potassium, it is quite different from typical potash granite in other compositions. Judging from the field occurrence, migmatization metasomatism melting is the formation mechanism of Anziling potash granite.

Three. Suizhong adamellite

The distribution of adamellite in Suizhong is large, and the relationship with the potassium granite in Shanhaiguan in the south is unclear, but it is likely to be formed in the front. From the rock mass to the north of Jinxi, the rock deformation is weak and the spatial composition changes little. Generally, it is medium-coarse, light-fleshed red, and grayish white after weathering. The mineral assemblages are chronological and two kinds of feldspar, often containing more dark mineral biotite (5% ~ 10%). The accessory minerals are zircon, apatite and sphene. Gneiss-like dark mass can be seen in Liucun, Gaodianzi Township, Suizhong, with potassium granite veins interspersed. The chemical analysis of the sample (LS920 1- 1) shows that SiO: is 7 1.06%, and the contents of K2O and Na2O are similar and high, which are 3.98% and 4.23% respectively. It is located in granite area on AB-An-OR diagram (Figure 4- 1 1). Light and heavy rare earths in rocks are separated, and heavy rare earths have a strong loss, and there is no obvious rare earth pattern of europium anomaly (Figure 4- 12d). Compared with Rb, th and Ba, there is no obvious loss, but high-field elements Nb and Ta have relative losses (Figure 4- 13b). The overall characteristics are different from those of Anziling complex.

Tuanshanzi adamellite near the sea in Suizhong area was previously classified as Suizhong adamellite in the north, but they are different in rock morphology and chemical composition. Tuanshanzi adamellite is gray-white, medium-coarse-grained, and the minerals have no orientation or weak orientation. It is mainly composed of chronological and sodium plagioclase, and the content of potash feldspar and biotite is relatively low. The Na2O of the rock (LS 9202) is obviously higher than K2O, the total amount of rare earth is very low, the separation of light and heavy rare earth is not strong, and there is no europium anomaly (Figure 4- 12d). On Pearce diagram, there are no negative anomalies of Nb and Ta in rocks, while P and Ti are relatively deficient, while Ba is relatively rich in Rb and Th (Figure 4- 13b). Of all the granitic rocks we analyzed, only Tuanshanzi adamellite has no negative anomalies of Nb and Ta. The characteristics of rock composition show that they may come from the source region of the lower crust lacking rare earths and have experienced strong crystallization differentiation. The isotopic age of Tuanshanzi granite has not been obtained, and the contact relationship between Tuanshanzi granite and Suizhong granite has not been reported. They may be younger granites, but judging from the cutting of diabase walls, they were formed at least before Mesoproterozoic.

Four, potassium granite

Shanhaiguan rock mass is the main potash granite in this area. Compared with typical potash granites, they have higher TFeO and CaO contents, so they are distributed in the upper part of granite area on AB-An-OR diagram. There are obvious negative europium anomalies in the rocks, and the heavy rare earth parts are flat (Figure 4- 12e), which is very similar to the potash granite in Anben area. Potash granite is also distributed in Jinxi area, but its scope is not clear. The analysis results of a sample (LJ9202) show that its major elements (high silicon, rich potassium and low sodium) and trace elements (Rb and Th obviously lose Ba, Nb, Ta and P strongly, as shown in Figure 4- 13C) are very similar to typical potash granite in other areas, but the total amount of rare earth is low and the negative europium anomaly is not obvious. This compositional feature of rocks may be related to the separation of accessory minerals rich in rare earths by strong crystallization differentiation in the later period. The sample LS920 1-2 is a potash granite vein with Suizhong adamellite. Judging from the obvious relative loss of Ba similar to Suizhong adamellite (LS920 1- 1), this vein is probably the product of further crystallization differentiation of adamellite. However, due to the difference of crystalline parent rock, it is also quite different from sample LJ9202 in composition, especially in the comparison of Ba-Rb-Th (Figure 4- 13C).

Fig. 4— Pearlite map of granitic rocks in eastern Hebei (including Suizhong-Jinxi, Liaoning).

A— Jielingkou diorite (round) and Anziling TTG granite (triangle); B- Suizhong adamellite; Potash granite in Suizhong-Jinxi area