VOLCANIC STRATIGRAPHY, HYDROTHERMAL ALTERATION AND TELLURIDE-BEARING EPITHERMAL DEPOSITS OF THE PATTERSON MINING DISTRICT, SWEETWATER MOUNTAINS, CA-NV

2016 ◽  
Author(s):  
Carli Balogh ◽  
◽  
Chris Holm-Denoma ◽  
Peter G. Vikre
Keyword(s):  
Hydrothermal Alteration ◽  
Mining District ◽  
Volcanic Stratigraphy ◽  
Epithermal Deposits

The Ajo Mining District, Pima County, Arizona--Evidence for Middle Cenozoic Detachment Faulting, Plutonism, Volcanism, and Hydrothermal Alteration

2006 ◽  
Author(s):  
Dennis P. Cox ◽  
Eric R. Force ◽  
William H. Wilkinson ◽  
Syver W. More ◽  
John S. Rivera ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Mining District ◽  
Pima County ◽  
Detachment Faulting

Fuchsite and other Cr-rich phyllosilicates in ultramafic enclaves from the Almadén mercury mining district, Spain

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 345-354 ◽  
Author(s):  
D. Morata ◽  
P. Higueras ◽  
S. Domínguez-Bella ◽  
J. Parras ◽  
F. Velasco ◽  
...  
Keyword(s):  
High Temperature ◽  
Hydrothermal Alteration ◽  
Large Range ◽  
Block Size ◽  
Hydrothermal Fluids ◽  
Mining District ◽  
Cr Content ◽  
Mercury Mining ◽  
Early Alteration

AbstractFuchsite and other Cr-rich phyllosilicates, paragenetic with dolomite, are present in some ultramafic enclaves from the ‘frailesca’ rock (a lapilli- to block-size pyroclastic lithic-tuff), in the Almadén mercury mining district, Spain. Analyses (EMPA and TEM) of fuchsite and Cr-chlorite showed a relatively large range in levels of Cr2O3. Petrographic relationships between these phyllosilicates and primary relics of Cr-spinel crystals, as well as their high Cr content, indicate that these Cr-rich minerals originated from primary chromian spinels through an early hydrothermal alteration stage. The hydrothermal fluids accounting for this early alteration would be of relatively high temperature, high aCO2 and aK, and variable aNa/K. In a later alteration stage, fuchsite was partially or totally replaced by illite and Cr-illite, giving rise to an argillitic alteration.

scholarly journals The Velardeña Zn–(Pb–Cu) skarn-epithermal deposits, central-northern Mexico: New physical-chemical constraints on ore-forming processes

2020 ◽  
Vol 72 (3) ◽  
pp. A270719
Author(s):  
Abigail Jiménez-Franco ◽  
Carles Canet ◽  
Pura Alfonso ◽  
Eduardo González-Partida ◽  
Abdorrahman Rajabi ◽  
...  
Keyword(s):  
Ore Deposits ◽  
The Other ◽  
Mining District ◽  
General Increase ◽  
Epithermal Deposits ◽  
Northern Mexico ◽  
Physical Chemical ◽  
Mineral Assemblages ◽  
Santa Maria ◽  
Mineral System

The Velardeña mining district is economically the most important of Durango state. The ore deposits occur in different skarn zones developed within the intrusive contact between Mesozoic limestones and Eocene granitic stocks and dikes. The most important ore deposits are related to the Santa María dike and Reyna de Cobre porphyritic stock (separated from each other by 10 km). They occur as irregularly shaped replacement masses developed near the intrusive contact and have a skarn paragenesis dominated by calc-silicates and sulfides. The mineral assemblages show replacement textures and are dominated by calcic clinopyroxene (Di97-53Hd42-02Jh04-01) and garnet (Ad100-57Grs43-00) in the exoskarn, with wollastonite particularly abundant in the endoskarn. Hydrous silicates are actinolite, epidote, and chlorite, whereas sulfides include pyrite, sphalerite, pyrrhotite, galena, chalcopyrite, and sulfosalts. Scheelite, hematite, quartz, and calcite are also present. According to sphalerite geobarometry, the skarns formed at hypabyssal depths (~3–4 km). They developed by a succession of replacive mineralizing events, including (a) a prograde stage at temperatures from ≥470 to 335 °C in conditions of low f (CO2), followed by (b) a retrograde stage from 335 to 220 °C. There was a general increase in f (O2), accompanying the temperature decline during the formation of the system, which accounts for a process of mixing with cooler, oxidizing, and dilute water. During the retrograde stage, wollastonite, calcic garnet and clinopyroxene formed. On the other hand, hydrous silicates, sulfides, sulfosalts, scheelite, and hematite crystallized during the retrograde stage. Skarn mineralization is crosscut by veins of calcite, fluorite, adularia, and sphalerite. The vein mineralization formed at temperatures below 200 °C. The different ore deposits of Velardeña constitute a telescoped skarn–epithermal mineral system.

scholarly journals Geology and geochemistry of jasperoids from the ‘Montaña de Manganeso’ district, San Luis Potosí, north-central Mexico

2021 ◽  
Vol 38 (3) ◽  
pp. 193-209
Author(s):  
Joseph Madondo ◽  
Carles Canet ◽  
Fernando Núñez-Useche ◽  
Eduardo González-Partida
Keyword(s):  
Hydrothermal Alteration ◽  
Hydrothermal Activity ◽  
Central Mexico ◽  
Mining District ◽  
High Angle ◽  
Geological Evidence ◽  
North Central ◽  
Hydrothermal Processes ◽  
Show Evidence ◽  
Feeder Zone

Large outcrops of jasperoids occur in the ‘Montaña de Manganeso’ mining district in north-central Mexico. They range from massive manganiferous jasperoids to highly brecciated, hematitic jasperoid. The jasperoids of ‘Montaña de Manganeso’ occur mainly as replacements of limestone, sandstone and shale, commonly nearby high-angle fault systems. The mineralogy of the jasperoids consist of quartz and its polymorphs (chalcedony, tridymite and cristobalite), Fe-Mn oxyhydroxides, calcite and minor barite. Many outcrops show evidence of several periods of brecciation and silicification. The geochemical signature of the jasperoids suggests that silicification was product of hydrothermal activity. The jasperoids display enrichment in elements of hydrothermal provenance such as Ba, Sr, As, Cr, Mo, Sb, Ni, Zn and Cu, whereas are strongly depleted in the elements indicative of clastic sources such as Ti, K, Th and Zr. Element ratios such as (Fe+Mn)/Ti, Al/(Al+Fe+Mn), Fe/Mn and U /Th, along with the Al-Fe-Mn and Fe-Mn-(Ni+Co+Cu)×10 ternary diagrams confirm a hydrothermal origin. Low ∑REE, an enrichment of LREE over HREE, negative Ce anomalies and positive Y anomalies (YPASS/HoPAAS) also support the hydrothermal processes. The geological evidence, in the form of a feeder zone and extensive hydrothermal alteration, show that the silica forming the rocks originated from ascending hot fluids.

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