Lamprophysic focus

The lamprophyre is a superficial diagenetic rock, usually dark in color, containing phenocrysts composed of dark minerals. When the naked eye is observed, its specimens are gleaming, hence the name. Its composition is mostly feldspar and the same dark minerals as phenocrysts, especially mica. According to its composition can be divided into:

Mica lamprophyre [1], the most common, black or grayish black, turned brownish yellow after weathering, phenocryst is mainly biotite; flash brilliant porphyry, black, black green or green, phenocryst is mainly amphibole and transparent Pyroxene, sometimes with olivine and biotite; alkaline lamprophyre, complex mineral composition, low siliceous content, phenocryst is mainly alkaline pyroxene or alkaline hornblende;

A general term for special dark vein rock. It is characterized by a full crystalline quality with a distinct plaque structure. The dark mineral content is very high, mainly including biotite, amphibole, pyroxene, and its content is not less than 30% in plaque or in the matrix, and the degree of self-formation is good. Common light-colored minerals are plagioclase, feldspar, etc., which are confined to the matrix; in addition, there are more volatile minerals. With the combination of dark minerals and light-colored minerals, it can be divided into Yunhuangyan, Yunshanghuangyan, Yinxiehuangyan, Lahuanghuangyan and Fangzhenghuang porphyry. Most of the porphyry veins are related to the deep diagenesis, intrusion into the rock mass or its surrounding rocks, and some are related to volcanic rocks, and often show signs of hydrothermal alteration. According to its composition, lamprophyre is almost all mafic or ultramafic rocks. According to the nature of phenocrysts compared with the matrix, it is speculated that some lamprophyre may be the cause of mixed dyeing. For example, some quartz-bearing Yunhuang rocks may be formed by the assimilation of granitic materials by basic magma. The term comes from the Greek lampros, meaning brilliant, shining.

A kind of dark, medium- or basic-alkali igneous rock with a plaque structure and more volatile components. Often produced by rock walls.

The porphyrite has a SiO2 content of generally 30 to 56% by weight, and is rich in FeO, MgO, Na2O and K2O (the first two contents are about 14 to 27% in total, and the latter two are about 3 to 10%). In addition, H2O, CO2, S, P2O5, Ba and rare elements are significantly higher than other igneous rocks with similar chemical composition. Therefore, the porphyry is in

The mineral composition of the porphyry is characterized by iron-rich magnesium minerals such as olivine, pyroxene, hornblende and black mica; the total content is generally greater than 35%, making the rock dark; the same iron-magnesium mineral often appears at the same time. In the phenocrysts and matrix; the iron-magnesium minerals in the phenocrysts are self-formed (sometimes semi-self-shaped), forming the characteristic plaque structure characteristic of the lamprophyre; the feldspar and the accessory feldspar are limited to the matrix; the calcite and zeolite and other hydrothermal minerals are mostly Primary minerals, sometimes together with minor feldspars, form the ocular sphere (common in alkaline porphyry), which is immiscible by the melt and forms in the late stage of magma crystallization in which the water vapor pressure rises and the melt boils. Huang feldspar may appear in alkali-based basal porphyry; in addition, lamprophyre may contain non-quantitative apatite, vermiculite,

Lamprophyre magnetite, chlorite, serpentine, talc, sulfide, etc.

The lamprophyre can be further named according to the combination and relative content of the minerals contained. Among them, four kinds of calc-alkaline lamprophyre, such as the Xuanzhengyan, the Yinxuanhuangyan, the Yunzhengyanyan and the Yunxuanhuangyan, are the most common. They are often associated with the post-orogenic granite granodiorite and diorite. Symbiotic, often wrapped in various rock-captures and feldspars, quartz-trapped twins, and feldspar, iron-magnesium mineral giant crystals. Alkaline boiling rock, black cloud boiling rock, Xiazhen Zhenghuang rock and Xiaxie oblique magmatic rock are alkaline lamprophyre, less common, often containing alkaline feldspar, ordinary pyroxene, titanium ordinary angular flash Stone and apatite giant crystals, and may contain olivine peridotite, pyroxene inclusions and granulite traps. Huangchanghuang porphyry is a rare alkali-based luminal porphyry, often enclosing the olivine peridotite inclusions and monoclinic pyroxene, orthopyroxene, biotite and amphibole giant crystal. The latter two types of basic and alkali superbasic lamprophyre are symbiotic with alkaline complexes and/or igneous carbonates.

In addition to the rock wall output, the lamprophyre can also be a vein, rock bed or rock neck.