Day 3, Hidrothermal Deposits, part 2

Today we are contrinue with the Hidrothermal study, regardint that geology is not an exact science. Geology is a science that deals with the study of the planet earth and studying millions and millions of years of developing and still continues to change, there are processes that are not yet known and theories vary but generally, it is on the way for become an exact science, but of course, many sciences are not either … So, let`s keep talking about…

Key factors for the formation of hydrothermal deposits:

  • Stock solutions capable of dissolving mineralizadoras and transporting mineral matter
  • Presence of openings in the rocks which solutions can be channeled
  • Presence of site locations for deposition of mineral content
  • Chemical reaction resulting in the deposition
  • Sufficient concentration of mineral matter deposited to reach explotatables make deposits

In Guatemala, the gold is found under all the factors listed above.  For Alluvial gold the factor with sufficient concentration of mineral matter deposits of gold are are available and exploitables.

 Typical hydrothermal deposit

Typical hydrothermal deposit

Character of the solutions

The nature of hydrothermal solutions must be interpreted by inference and by analogy with certain types of hot springs. Its action is visible only in the form of mineral deposits or as an alteration of the rock. As the word implies hydrothermal waters are probably hot with temperatures ranging between 500 ° C and 50 ° C. The high temperature are also at elevated pressure. In Guatemala, these deposits are mostly over 1,500 meters above sea level. Places west of the country as Huehuetenango, San Marcos, El Quiché, Alta Verapaz and Baja and in parts of east, especially in the area of Chiquimula, where there are high elevations.

Openings in the rocks

The displacement of the hydrothermal solutions from its origin to the place of deposition depends largely openings which are found in rocks. The deposition of large foreign minerals implies the need for a continuous supply of new matter, and this means that there must be traffic conduits. The openings have to be interconnected. Furthermore, it is evident that the cavity filling deposits can not be formed unless there are likely to be filled cavities. It is also evident that substitution deposits can not form unless the solutions to reach the rock undergoing substitution. Therefore, the openings in the rock are essential for epigenetic deposit formation. Also essential to the existence of groundwater bodies, oil and gas.

Different types of openings in the rocks which can serve as receptacles for minerals or allow displacement of solutions or its constituents through the rocks can be classified
as follows:

Early Chambers

  • Crystal lattices:

The spaces between the atoms of the crystal can allow diffusion of ions of smaller ionic radius. This diffusion can allow substitutions or additions occur in crystals, such as quartz and feldspar associated.

cuarzos alterados

Altered quartz

This type of phenomenon can be found in the mountainous region of El Chol, Baja Verapaz where there is a mining extration of feldespar related with quartz, useful for the production of toilets, tubs and sinks.

  •  Expulsion of lava conduits:   They are formed in the lava flows solidified when the outside of it, and the remaining liquid lava in the center drains out leaving a tube or tunnel.
  • Cracks cooling:  Form as a result of the contraction on cooling igneous rocks. They can be regularly spaced joints that divide the rock into blocks or parallel fractures smooth or irregular cracks.
  • Igneous breccia :
    Igneous gaps are of two types:Volcanic breccias that form clusters

    Gaps intrusion.

    Both are composed of angular fragments of igneous rocks and thick, with finest materials in the interstices. They may be completely permeable.

BRECHA_2

Rocks in breach, notice how the smaller rocks are arranged to form a single piece

  • Levels of stratification:  They are well-known features of all sedimentary formations. Allow entry of hydrothermal solutions and the substitution of mineral ores with adjacent walls.

Chamber Formations

Fissures with or without faults:
Fissures are continuous tabular openings in rocks, usually of considerable length and depth. The forces originate compression, tension or torque acting on the rocks and can go or not accompanied by failures. Thus, the faults are cracks, but not all are necessarily failures cracks. They can provide long continuous lines for solutions. When are occupied by metal or mineral veins are fissure.

Cavity shear zones:
The shear zones when fractures occur, rather than concentrated in one or two individual tear, break into innumerable breakage and crushing surfaces, spaced very little despite being discontinuous, more or less parallel. Generally faults are present. Openings thin and leafy, mostly of infinitesimal size, are excellent conduits for solutions, as evidenced 1as copious streams that flow through them in places where they form tunnels and mines. Because of the tiny apertures, they can only occur in less deposition in open space, but the large surface area available for shearing zones which are favorable for substitution deposit location.

Chambers due to folding:

  • Crests of folds
  • Slopes and plains
  • Cracks and broken anticlines and synclines

The bending and folding of the sedimentary layers give rise to:

  • folding ridges openings  in the narrow ridges anticlines closely folded
  • slopes, which are highly inclined, and plain, openings formed the fracture of layers a slight sinking
  • Longitudinal cracks along the crests of the anticlines and synclines.
yolcultac

Yolcultac, uptown in the department of Huehuetenango, inclined slopes can be seen, very inclined …

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