In:
Geology, Geological Society of America, Vol. 51, No. 2 ( 2023-02-01), p. 189-192
Abstract:
High-grade ores in low-sulfidation epithermal precious metal deposits include banded quartz veins that contain gold dendrites. The processes by which dendrite growth takes place have been subject to debate for decades, especially given that these deposits are known to form from dilute thermal liquids that contain only trace amounts of gold. It is shown here that growth of gold dendrites in epithermal veins at the McLaughlin deposit in California (western USA) originally took place within bands of gel-like noncrystalline silica. The gel provided a framework for the delicate dendrites to form. The high permeability of the gel allowed the diffusion and advection of gold from the thermal liquids flowing across the top of the silica layers to the sites of crystal growth within the gel. Over time, the gel hardened to form opal-AG. This silica phase is thermodynamically unstable and recrystallized to quartz that has a distinct mosaic texture.
Type of Medium:
Online Resource
ISSN:
0091-7613
,
1943-2682
Language:
English
Publisher:
Geological Society of America
Publication Date:
2023
detail.hit.zdb_id:
184929-3
detail.hit.zdb_id:
2041152-2
SSG:
13
