The observation of magmatic rock using borehole inspection cameras

Borehole inspection cameras observe the structure of magmatic rock. Based on this, it can be distinguished whether it belongs to plutonic rocks, shallow diagenetic rocks or extruded rocks.

According to the degree of crystallization of each component in the rock, it can be divided into structures such as full crystalline, semi-crystalline and vitreous. not only distinguish the apparent crystalline or cryptocrystalline structure from the full crystalline structure, but also further subdivide the apparent crystalline structure rock according to its mineral particle size into equal grains, unequal grains, coarse grains or fine grains. For rocks with porphyritic structure, the phenocryst composition, matrix composition and degree of crystallization should be described.

If the mineral particles in the rock are large and have an isogranular and porphyritic structure, they belong to plutonic rocks. If the mineral particles are fine and dense, with a cryptocrystalline and vitreous structure, they are generally exuded rocks.

If the minerals in the rock are of fine-grained and porphyritic structure, that is, between the above two, they belong to the diagenetic rock.By observing the directional arrangement of minerals in the rock, we can infer the formation environment of the rock, how much volatile components it contains, and the direction of magma flow. If there is no directional arrangement, it is called a block structure; if there is a directional arrangement, it may be a rhyolite structure, a stomatal structure or a striped structure. Plutonic rocks and primordial rocks are mostly block structures; extruded rocks are rhyolite structures and pore structures. Observe the direction of long columnar minerals and stomatal xenoliths that are regularly arranged in the rock. For those flaky minerals that are regularly arranged on the contact surface, their composition should be described and their occurrence elements should be measured.