argillic alteration

argillic alteration

[är′jil·ik ‚ȯl·tə′rā·shən]
(geology)
A rock alteration in which certain minerals are converted to minerals of the clay group.
References in periodicals archive ?
Drill hole PU-RC-94, drilled 5km southeast of PU-RC-80 in the north eastern portion of the Pampa Union block, intersected what the company interprets to be a new prospective area for porphyry mineralization, with strong phyllic and argillic alteration within a porphyritic andesite unit.
A visual analysis of the LANDSAT H image shows that argillic alteration (contrast between 1650 and 2215 nm) is associated with dark pixels instead of bright pixels.
These could be grouped into hardness geometallurgical domains, such that it was found that green mica alteration is always related to harder rocks, potassic alteration with intermediate hardness, and phyllic and argillic alteration with softer rocks.
Wildhorse Plain hosts an area of probable epithermal alteration made up of fluorite, argillic alteration and minor sulphide.
Multiple veins have been identified, with argillic alteration and erratic silver and gold values.
According to Dia Bras, "high grades of gold in outcrop over two structural trends, as well as highly anomalous stream sediment samples that indicate a gold mineralized area in the core of the large argillic alteration area" exist on the La Verde Prospect.
A recent field campaign in the area (see FIGURE 1) allowed identifying argillic alteration (no differentiation was made between intermediate and advanced in field) and silicification with vuggy silica (found in a isolated outcrop affected by the Villamaria-Termales fault and near to a hot spring with 63[degrees]C in temperature).
In the course of its investigations, the ICGRSG team also discovered several areas of probable argillic alteration and ferruginous outcrops of the types associated with hydrothermal deposits.
The strong argillic alteration of the host rocks has been interpreted to represent the upper portions of a high sulfidation deposit.
The gold is found in association with pyrite and argillic alteration is pervasive.
Sericitic and argillic alteration are also widespread, especially in the underground exposures, where fracture association is also evident.
Gold mineralization is associated with quartz veining, silicification, argillic alteration and anomalous arsenic, antimony, and silver.