Geology and mineralogy of the Santo Nino Ag-Pb-Zn vein, Fresnillo District, Mexico

Conference · Tue Jan 01 00:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6596801

Gemmell, J B; Zantop, H; Birnie, R W

The Santo Nino Ag-Pb-Zn vein is the major producer of the Fresnillo District, located 750 km NW of Mexico City. It is over 2.4 km long, more than 480 m in vertical extent, more than 2.5 m wide overall, and has average grades of >600 gm/t Ag and <2% combined Pb and Zn. The vein is hosted by a tilted sequence of Cretaceous graywackes, shales and andesitic volcanics and extends upward into a Lower Tertiary conglomerate. Up to 5 separate opening events occurred along the vein, resulting in discontinuous stages of brecciation and crustiform banding. Ore mineral zonation is well developed both vertically and laterally and closely reflects metal and metal ratio distributions. Ore minerals are sphalerite, galena, pyrite, chalcopyrite, arsenopyrite, marcasite, pyrrhotite, acanthite, native silver, and three coexisting solid solution series, pyrargyrite-proustite, polybasite-arsenopolybasite, and tetrahedrite-tennantite in a gangue of quartz, calcite, clay, sericite,and chlorite. A 5-stage paragenetic sequence can be established: 1) pyrite, arsenopyrite, quartz, 2) sphalerite, galena, chalcopyrite, quartz, 3) tetrahedrite, pyrargyrite, polybasite, quartz, 4) acanthite, native silver, calcite, quartz, and 5) calcite. Preliminary microprobe analyses indicate that the Ag-rich solid solution series are Sb-rich in the central and upper portions of the vein and As-rich at deeper levels.

• Research Organization: Dartmouth College, Hanover, NH (USA)
• OSTI ID: 6596801
• Report Number(s): CONF-8510489-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
LEAD ORES
MINERALIZATION
MINERALOGY
MEXICO
SILVER ORES
ZINC ORES
CHALCOPYRITE
CRETACEOUS PERIOD
GALENA
GEOLOGIC HISTORY
GRAYWACKE
MARCASITE
PETROGENESIS
PYRITE
SHALES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER SULFIDES
DEVELOPING COUNTRIES
GEOLOGIC AGES
IRON COMPOUNDS
IRON SULFIDES
LATIN AMERICA
LEAD COMPOUNDS
LEAD SULFIDES
MESOZOIC ERA
MINERALS
NORTH AMERICA
ORES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
580300* - Mineralogy
Petrology
&amp; Rock Mechanics- (-1989)