Donald C. Ross 1973 <p>Trondhjemitic rocks are relatively abundant in the granitic&nbsp;terranes of the western Sierra Nevada and the Klamath Mountains but&nbsp;have not been found in the granitic plutons of the Salinian block, which&nbsp;lies westward, across the San Andreas fault. A ternary plot of modal&nbsp;quartz : K-feldspar : plagioclase from more than 200 granitic samples&nbsp;from the Salinian block has an elongate, nearly horizontal, quartz-rich&nbsp;trend that appears trondhjemitic to some observers. However, petrographic&nbsp;and chemical comparison of these rocks with trondhjemite&nbsp;from the type area in Norway and with rocks called trondhjemite in the&nbsp;Western United States shows that the granitic rocks of the Salinian&nbsp;block are not trondhjemitic. The absence of trondhjemite in the&nbsp;Salinian block further supports the contention that this terrane is not&nbsp;merely a westward continuation of Sierran basement but is a displaced&nbsp;basement block.</p> application/pdf en U.S. Geological Survey Are the granitic rocks of the Salinian block trondhjemitic? article