Zircons in volcanic rocks

Slow oxygen diffusion rates in igneous zircons from metamorphic rocks

Empirical tests of oxygen exchange rate in zircon crystals from amphiboliteand granulite-facies metamorphic rocks of the Grenville Province demonstrate preservation of igneous dO through protracted igneous and metamorphic histories, forming the basis of quantitative estimates of diffusion rate. Granitic orthogneisses, which cooled slowly after granulite-facies metamorphism, show no consistent r...

Generalized Titanomagnetite in Hawaiian Volcanic Rocks'

A ferromagnetic oxide mineral with spinel structure was separated from Hawaiian volcanic rocks ranging from basalt to trachyte . The chemical compositions of all the specimens have been arranged on an oxygen reaction line, and can safely be interpreted as the result of a process of either oxidation or reduction of material with composition on or near this line. In the trachyte the mineral was f...

Groundwater in Sedimentary, Metamorphic and Volcanic Rocks

Ultrasonic velocity measurements in volcanic rocks: correlation with microtexture

This paper summarizes results of a study of porosity, permeability, microstructure and acoustic properties of volcanic and pyroclastic rocks fromCampi Flegrei (CF) andMt. Etna (ET), Italy. We have measured the hydraulic, transport and acoustics properties of 28 room-dry samples at ambient conditions, 25 room-dry samples under confining pressure (up to 60 MPa) and 5 brine saturated samples under...

Isotopic composition of strontium in volcanic rocks from oahu.

Analysis of several well-documented specimens from each of the three volcanic series on Oahu gives the following mean ratios of Sr(87) to Sr(86): the Waianae series, 0.7030 +/- 0.00010 (sigma); the Koolau series, 0.70385+/- 0.00009 (sigma); and the Honolulu series, 0.7029 ++/- 0.00006 ( sigma). The mean ratio of Sr(87) to Sr(86) of the Koolau series specimens is significantly higher than the me...