Thermal aureoles of igneous intrusions: some possible indications of hydrothermal convective cooling

Journal Article · Thu Jan 01 04:00:00 EST 1981 · J. Geol.; (United States)

DOI:https://doi.org/10.1086/628561· OSTI ID:7054705

Parmentier, E M; Schedl, A

The size and shape of metamorphic aureoles is investigated as a possible indicator of hydrothermal convective cooling of epizonal igneous intrusions. A simple family of numerical models illustrates the effect of convective cooling on maximum temperatures attained in the country rock surrounding an intrusion. Boundary layer approximations have also been applied to describe convection of vaporizing groundwater near the contact of an intrusion early in its cooling history. Maximum temperature isotherms are taken to reflect the width and shape of thermal aureoles defined by preserved mineral assemblages as appears to be reasonable based on several well-studied conductively cooled intrusions. The thermal aureoles of intrusions for which oxygen and hydrogen isotope data indicate convective groundwater circulation have been examined on the basis of the simple numerical and boundary layer models. The shape of the low temperature alteration aureole of the well-mapped El Salvador porphyry copper deposit suggests convective cooling of a permeable intrusion. The width of the low temperature (greenschist) aureole of the Mull intrusive complex can be explained by convective cooling of permeable intrusive rock. The narrow high temperature (amphibolite) aureole of the Cuillin gabbro on Skye can be explained by strong convective cooling; but the low temperature (greenschist) aureole is wide enough to be consistent with conductive cooling, thus suggesting decreasing permeabilities during the cooling history. This is consistent with oxygen isotope sampling and other geologic observations.

• Research Organization: Brown Univ., Providence, RI
• OSTI ID: 7054705
• Journal Information: J. Geol.; (United States), Journal Name: J. Geol.; (United States) Vol. 89:1; ISSN JGEOA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
BOUNDARY LAYERS
CONVECTION
COOLING
ENERGY TRANSFER
GEOTHERMAL SYSTEMS
HEAT TRANSFER
HYDROTHERMAL SYSTEMS
IGNEOUS ROCKS
INTRUSION
ISOTOPES
LAYERS
MATHEMATICAL MODELS
METAMORPHIC ROCKS
OXYGEN ISOTOPES
PERMEABILITY
PLUTONIC ROCKS
ROCKS