Geologic, fluid inclusion, and stable isotope studies of the tin-tungsten deposits of Panasqueira, Portugal

Kelly, William G.; Rye, Robert O.

doi:10.2113/gsecongeo.74.8.1721

Cited by 255 publications

(211 citation statements)

References 0 publications

Supporting

Mentioning

197

Contrasting

Unclassified

Order By: Relevance

“…Map of Portugal showing the location of Panasqueira and the distribution of the Hercynian granitic rocks (redrawn after Inverno and Ribeiro, 1980). northern Portugal (Kelly and Rye, 1979). The sub-horizontal ore veins are enclosed within a tightly folded schist and greywacke complex of Pre-Cambrian to Carboniferous age, the Beira Schists, into which the granites involved were emplaced.…”

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%

“…The veins consist predominantly of quartz, with wolframite, cassiterite and chalcopyrite present in economic concentrations. The paragenetic sequence is quite complicated (for simplified versions see Kelly and Rye, 1979;Polya, 1989). The veins cut a greisenised granitic cupola, which crops out within the mine workings, but are not restricted to its vicinity.…”

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%

“…These authors proposed depths of formation for the fracture system of between 1 and 2 km below the water table using fluid inclusion results and phase relationships in the system NaC1-H20-CO2 for a boiling (effervescing) fluid. Kelly and Rye (1979) recognised that the Panasqueira vein morphologies suggested that they were predominantly dilational structures formed by the forceful intrusion of fluid. They compared the structures (stepped margins and splitting veins) to those seen within magmatic dykes by Pollard (1973) and they similarly proposed that the fluids responsible for fracturing and dilation forced their way upwards into the schists from a reservoir below the deposit.…”

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%

“…The driving mechanism for the extension within the Beira Schists was fluid pressure. The processes causing such abnormal fluid pressures within the area have been linked to the crystallisation of granite and the release of volatiles, though the involvement of meteoric waters has also been inferred (Kelly and Rye, 1979;Polya, 1989).…”

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%

“…Kelly and Rye (1979) tried to overcome this difficulty and suggested that as only some minerals showed consistent relative age relationships, any paragenetic sequence should be based chiefly on those minerals. As an aid to understanding such paragenetic variations the temporal and spatial relationship between the end-member textures in the Panasqueira vein system is investigated in this paper using structural and textural observations.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Textural evolution of W-Cu-Sn-bearing hydrothermal veins at Minas da Panasqueira, Portugal

1991

View full text Add to dashboard Cite

Combined structural and textural studies of the quartz veins of the Panasqueira W~Cu-Sn deposit of central Portugal have revealed the presence of coeval forms of crack-seal and cavity-fill mineral textures. The textures result from the dilational and infilling histories of brittle fractures produced within the host rock by the intrusion of pressurised fluids. Crack-seal textures were produced wherever or whenever crystal growth rates matched or were greater than fracture dilation rates, whereas cavityfill textures developed wherever or whenever dilation rates were quicker than those of crystal growth. Rates of dilation within the blade-like fissures were naturally lowest at the edges, where types of crackseal textures were produced, and highest in the cores, where cavity-fill texture formed. During propagation the linkage of adjacent echelon blades, by the rupture of the host-rock straps (bridges) between them, enhanced dilation rates and led to the widespread development of cavity-fill textures. Within the composite fissures so produced, environments in which types of crack-seal textures could form were restricted to the fissure margins and to areas where the tensile strain was sympathetically shared between closely spaced fissures. Textures and minerals characteristic of each fracture environment were able to form simultaneously within the fracture system.

show abstract

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%

Section: Beira Schist ~ Early Precambrianmentioning

confidence: 99%