... magmatic-hydrothermal events in close proximity to the porphyry deposits. The propylitic alteration halos that surround the Cu-Au deposits contain widespread hydrothermal titanite, as do the younger altered volcanic and intrusive rocks. Here, we present a comprehensive laser ablation-inductively coupled...

...Adam Pacey; Jamie J. Wilkinson; Adrian J. Boyce; Ian L. Millar Abstract In porphyry ore deposit models, the propylitic alteration facies is widely interpreted to be caused by convective circulation of meteoric waters. However, recent field-based and geochemical data suggest that magmatic-derived...

...Jamie J. Wilkinson; Michael J. Baker; David R. Cooke; Clara C. Wilkinson Abstract The mineral chemistry of epidote and chlorite from the propylitic halo at El Teniente, in samples collected at distances up to 6.6 km from the deposit center, was determined by microprobe and laser ablation...

.... Alteration mapping represents an effective technique for prospecting for hydrothermal deposits, but, in low-grade metamorphic terrains, recognition of propylitic assemblages that represent the boundary of the mineralizing system is hampered by their resemblance to metamorphic mineral assemblages. Our results...

...M. Cassiaux; D. Proust; M. Siitari-Kauppi; P. Sardini; Y. Leutsch Abstract The porosity of a propylitized granite from Charroux (France), with no fractures or sealed fractures, increases by more than four times from the unaltered (0.3%) to the altered rock (1.4%). This evolution results from...

... system near Tintic, Utah. Propylitic alteration of volcanic rock can be subdivided into actinolite, epidote, and chlorite subzones. An actinolite subzone containing actinolite, epidote, chlorite, and calcite extends 250 m away from the secondary biotite zone. An epidote subzone containing epidote...

... (10,000,000 oz) of gold (including 277,000,000 metric tons ore at 1.2 ppm Au as open-pit reserves plus past open-pit production) occur in tuff overprinted by both early, pervasive propylitic alteration (quartz-adularia-albite-chlorite-calcite-pyrite + or - epidote) and later, more fracture-controlled potassic...

...J. I. Lindley; P. C. Ragland; C. E. Chapin ABSTRACT Large-scale propylitic alteration of two texturally distinct, Oligocene ash-flow tuffs has been investigated: the crystal-poor, one-feldspar, rhyolitic A-L Peak Tuff and the crystal-rich, two-feldspar, rhyolitic to quartz latitic Hells Mesa Tuff...

... of the hydrothermal fluids. During propylitic overprinting of potassic alteration changes in whole-rock geochemistry relate to the destruction of biotite (both igneous and hydrothermal) and the formation of chlorite, epidote, calcite, and apatite. These changes result in the loss of ail rare-earth elements (REE) due...

...Robert Roy Coats Abstract Descriptions of several occurrences of propylitized andesites are reviewed, including the original descriptions of "propylites." The principal explanations that have been offered for propylitization are: (a) dynamometamorphism; (b) autohydration; (c) origin through post...

...DONALD C NOBLE Abstract Chemically unaltered calcium-bearing plagioclase (An 20 –An 60 ) of volcanic origin is found in propylitically altered and low-grade metamorphosed volcanic rocks from several areas. Although parts of the relict plagioclase phenocrysts are replaced by albite or by other...