المحاليل الحرمائيه ورواسبها Hydrothermal Solutions and their Mineral Deposits الخامات والرواسب المعدنيه الحرمائيه هى تلك الرواسب التى تتكون بواسطه محاليل مائيه ممعدنه وفى درجات حراره مختلفه. تضم هذه الرواسب مجموعه كبيره ومتنوعه لمعظم العناصر، ومن أمثله هذه الخامات: رواسب الكبريتيدات البركانيه الكتليه Volcanogenic Massive Sulfide (VMS) Deposits الرواسب العرقيه Vein Deposits رواسب النحاس البورفيرى Porphyry Copper Deposits رواسب السكارن Skarn Deposits
Origins of the Solutions Magmatic Sources Meteoric water (ground water) sources Seawater sources Regional Metamorphism !
hydrothermal system
Composition of the Solutions The principle ingredient of hydrothermal solutions is a brine – hot water Containing dissolved salts such as NaCl, KCl, CaSO4 and CaCl2 The range in salinity varies from that of seawater to about ten times the salinity of seawater Capable of dissolving small amounts of elements such as Au, Ag, Cu, Pb and Zn High temperatures increase the effectiveness of the brines to dissolve metals
Causes of Mineral Precipitation a convection cell is required to maintain a constant precipitation Rapid movement of the fluid into porous layers (open fractures such as veins and brecciated rocks) Sudden cooling of the fluids leads to rapid precipitation of minerals over a limited region Boiling, rapid pressure decrease, reactions with adjacent rock types, and mixing with seawater can also cause rapid precipitation and the concentration of mineral deposits.