Numerical experiments on /sup 18/O depletion in igneous intrusions cooling by groundwater convection

Journal Article · Mon Aug 10 04:00:00 EDT 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB086iB08p07131· OSTI ID:5939855

Parmentier, E M

The intrusive and host rocks of epizonal igneous intrusions cooled by groundwater convection are depleted in /sup 18/O by oxygen exchange with low-/sup 18/O meteoric waters. This study describes numerical experiments on the hydrothermal convective cooling and /sup 18/O depletion of a family of simple two-dimensional model intrusions. Cooling and depletion histories are calculated on the basis of conservation laws for mass, Thermal energy, and /sup 18/O atoms along with Darcy's law to describe flow in permeable rock and a kinetic description of water-rock oxygen exchange. Exchange is described on the basis of the measured oxygen diffusivity in feldspar which is large compared to that in the other rock-forming minerals. The resulting equations are solved using finite difference approximations. The numerical experiments examine the effect of intrusion size, intrusive and host rock permeabilities, and host rock thermal environment on the /sup 18/O depletion that develops as an intrusion cools and show that the depletion patterns in a cooled intrusion are sensitive to parameters describing the intrusion and its environment. The dependence of several general characteristics of these patterns on the model parameters is described. Depletions obtained from the sampling of natural intrusions are discussed in the context of this sample family of models.

• Research Organization: Department of Geological Sciences, Brown University, Providence, Rhode Island 02912
• OSTI ID: 5939855
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 86:B8; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580200 -- Geophysics-- (-1989)
580202* -- Geophysics-- Volcanology-- (1980-1989)
CONVECTION
EVEN-EVEN NUCLEI
GROUND WATER
HYDROGEN COMPOUNDS
INTRUSION
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MAGMA
MAGMATISM
NUCLEI
NUMERICAL SOLUTION
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
ROCK-FLUID INTERACTIONS
STABLE ISOTOPES
TWO-DIMENSIONAL CALCULATIONS
WATER