by Andrei KARAKIN, Dr. Sc. (Phys. & Math.), All-Russia Research Institute of Geologic, Geophysical and Geochemical Systems
How do mineral deposits take body and form? If we get an answer to this question, we shall be able to make mineral prospecting much more reliable and cost effective. But this problem is still mooted.
Our planet has a fairly complex structure, with the inner and outer core in the center, and the mantle and the lithosphere above. The outer part of the lithosphere, the crust, is about 35 to 40 km thick in continental zones (which is thinner than an apple's skin by comparison); in its turn, the crust is broken down into lower, middle and upper regions. These are a medium where all the various fluids-gases, liquids (water, oil, solutions) and melts keep circulating.
Such substances may be of abysmal or surface origin, that is juvenile and meteoric, respectively. Geologists have been debating for decades which of these two prevail. It is important to know that so as to elucidate, among other things, the hydrocarbon formative mechanism. They, who content that juvenile fluids are predominant, say: petroleum and other liquids rise from the earth's interior. But their opponents claim: petroleum, the "black gold", comes from organic matter residues. Scientists differ about ore deposits, too. Most of them argue that ores have got into the crust from plutonic depths together with melts or have appeared as a result of action of surface waters in the process of deposition and redeposition of sedimentary rock. According to another viewpoint, the movement of aqueous fluids in the cool upper crust has contributed to the concentration of mineral compounds. We might as well add that many geoecological problems are related to this very phenomenon. For instance, toxic substances released during petroleum and gas mining pollute the surface layers of the earth crust and escape into the atmosphere. And moisture penetrating into minute cracks of hard rock erodes i ... Read more