Metamorphic units- Several types of metamorphic rocks are found in the range, including quartzo-feldspathic gneiss (figure 3), amphibolitic gneiss, and heavily foliated rocks of granitic, and dioritic origin. These metamorphics are strongly banded on both cm and meter scale. The likely protolith of these units is the Union Hills and Alder Groups, which are a series of volcanic (both basaltic and andesitic) and volcanic clastic rocks found in the Transition Zone.
Foliated tonalitic and granodioritc plutons-
Foliated intrusive rocks are also found to the north and south of
the metamorphics. Though these plutons can contain compositional
banding and intense foliation, they are distinguished by their
mineralogy and grain size (which is generally coarser than the
metamorphics). These bodies appear to have intruded either
during or between foliation forming events as tabular sheets that
are elongate along the strike of the S1 foliation.
Figure 3. Photograph of
quartzo-feldspathic gneiss in the southern White Tank Mtns. The
gneiss is banded on the cm scale with amphibolitic gneiss.
A Proterozoic pegmatite vein (right center of view) has
locally disrupted and complexly folded the gneiss.
Bedrock Geology Project
Proterozoic rock units
Remote Sensing techniques
References and Acknowledgments
Geology and Web pages by Steven Wood and Stephen J. Reynolds, Dept. of Geology, Arizona State University, Tempe, AZ -- July 1998