Volcanic rocks from Temiscouata Lake, Que

Backstay and Irvine: Alkaline Volcanic Rocks from Gusev

Introduction: Study of the Martian crust by orbital spectroscopy and SNC meteorites has so far only recognized subalkaline volcanic rocks. However, Spirit rover measured high alkalis and low silica in picritic basalts on the Gusev plains [1,2], allowing the possibility that alkaline differentiates might occur. Isolated rocks having mildly alkaline compositions and distinctive spectra have now b...

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...

Geochemical Constraints on the Origin of Volcanic Rocks from the Andean Northern Volcanic Zone, Ecuador

Whole-rock geochemical data on basaltic to rhyolitic samples from 12 volcanic centers are used to constrain the role of continental crust in the genesis of magmas formed beneath the anomalously wide subduction-related volcanic arc in Ecuador. Relatively homogeneous, mantle-like, isotopic compositions across the arc imply that the parental magmas in Ecuador were produced largely within the mantl...

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