A vein occurrence of co-existing talc, saponite, and corrensite, Builth Wells, Wales

Laurence Garvie, R. Metcalfe

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Unique phyllosilicate assemblages occur in quartz-calcite veins cutting altered andesite at Builth Wells, UK. These veins show: (1) central talc-dominated assemblage, grading into a saponite/corrensite/chlorite-dominaled assemblage near their walls; (2) talc replacing calcite and quartz; and (3) closely associated blocky and fibrous saponite. Fibrous saponite occurs in narrow (<1 cm) fractures that extend for up to 1 m from major (≤ 50 cm wide) talc-bearing veins. A thin halo (<5 mm) of wall-rock alteration, containing blocky saponite and minor corrensite, borders the fibrous saponite. These minerals may have originated when cooling, low-pH, quartz-saturated, Mg-rich fluid invaded pre-existing quartz/calcite veins. Quartz is replaced by talc where calcite dissolution caused the pH to increase. Wallrock alteration liberated Fe and Al to the fluid causing blocky saponite and corrensite to form. Fibrous saponite formed where lithostatic pressures were directed across hydraulic fractures.

Original languageEnglish (US)
Pages (from-to)223-240
Number of pages18
JournalClay Minerals
Volume32
Issue number2
DOIs
StatePublished - Jan 1 1997

Fingerprint

corrensite
Talc
saponite
talc
Quartz
Calcium Carbonate
well
quartz
calcite
Bearings (structural)
Wall rock
Fluids
fluid
phyllosilicate
wall rock
andesite
chlorite
Minerals
Dissolution
dissolution

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

A vein occurrence of co-existing talc, saponite, and corrensite, Builth Wells, Wales. / Garvie, Laurence; Metcalfe, R.

In: Clay Minerals, Vol. 32, No. 2, 01.01.1997, p. 223-240.

Research output: Contribution to journalArticle

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