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 ?
Drilling has identified that this CSAMT geophysical anomaly appears to be related to advanced argillic alteration ('lithocap') under cover.
The prospect is defined by a large 1.5-by-1-kilometer zone of argillic alteration, with the alteration zone possibly related to an epithermal gold system.
The alteration zones of a typical porphyry system are also present including propylitic and potash, while, some phyllic and argillic alteration has also been observed.
The Pemberton Hills target is a 3.5 km by 1.5 km area of advanced argillic alteration of a type often found overlying porphyry copper deposits.
Wildhorse Plain hosts an area of probable epithermal alteration made up of fluorite, argillic alteration and minor sulphide.
Nor is there a zonation of oxygen isotopic compositions that would be predicted for intrusion-driven water-rock interaction--magmatic fluids near the intrusive centres followed progressively outwards by [[sup.18]O-depletion (propylitic alteration) and then [[sup.18]O-enrichment (argillic alteration), as meteoric-hydrothermal waters became dominant in the cooling system through circulatory fluid flow above the brittle-ductile boundary as is evident in the distribution of [[delta].sup.18][O.sub.WR] values in Figure 4.
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.
The incidental discovery of sizeable potential argillic alteration in the Kunlun is a 'bonus' discovery and may be related to the gold in the Hotien district.