NEW GEOLOGIC MAP COMPILATION, WITH REVISED TECTONOSTRATIGRAPHIC INTERPRETATION, OF THE SIERRA NEVADA, CALIFORNIA AND NEVADA

We present a newly compiled geologic map of the Sierra Nevada and a bit of the surrounding region prepared as part of the upcoming Sierra Nevada Digital Earth Science Atlas. The map was prepared for display at 1:400,000, appropriate for plotting on a 40 X 66 inch (1016 × 1676 mm) page. Contacts were simplified from source maps to be legible at that scale, and units too small to discern at that scale were omitted or deleted.

The map was prepared in four layers:

1. Glacial deposits and large landslides
2. Late Cretaceous and Cenozoic cover strata
3. Basement rocks west of the Melones-Gillis Hill-Dogwood Peak fault, which roughly bisects the rocks west of the batholith in the northern and central part of the area
4. Basement rocks of the remainder of the map area (initially prepared by the late W.J. Nokleberg, who began the atlas project)

Basement rocks, defined here as Paleocene and older metamorphic and plutonic rocks, are divided into tectonostratigraphic units, primarily terranes and plutonic complexes, many of which are subdivided into lithologic or tectonic sub-units. Plutonic complexes are combined with roughly coeval metavolcanic rocks into “arcs”, representing the remains of relatively long-lived (10s of m.y.) periods of continental margin arc volcanism. In the western foothills (Layer 3), the basement is grouped into three terranes, two of which make up a superterrane stitched by ~165-168 Ma plutons, overlain/intruded by Middle and Late Jurassic sedimentary and igneous rocks, and subsequently intruded by Late Jurassic and Early Cretaceous plutons. In the eastern Sierra Nevada, the roof pendants comprise a suite of “arcs” that were progressively amalgamated and intruded/overlain by subsequent “arcs”.

Late Cretaceous and Cenozoic cover strata are grouped into a series of sedimentary and volcanic rock units. Sedimentary units are grouped by age and depositional environment and record Late Cretaceous to Quaternary sedimentation in fluvial, marine, basinal, and eolian environments. Volcanic rock units are grouped by age and composition and record late Eocene to Quaternary magmatism in varied tectonic regimes.

Glacial deposits are common throughout moderate to higher elevations and latitudes of the Sierra Nevada and record many periods of glaciation occurring from ~2.7 Ma to ~0.1 ka. Landslide deposits are also prevalent and include several mega-landslides in the Owens Valley.