New U-Pb ages for the Eastern Mesozoic Belt of northeastern California: Implications for stratigraphy, tectonic evolution, terrane assignment and possible correlation with Mesozoic units in the western Great Basin of Nevada


The northwest-striking, southwest-dipping, volcanic rock dominated Eastern
Mesozoic Belt (EMB) of northeastern California is the host of the Plumas copper belt.
The exposure belt can be divided into three depositional sequences. The late
Sinemurian/early Pliensbachian through early ToarcianKettle Rock sequence (KRS)
consists of shallow marine clastic and carbonate rock, coarse tuff breccia, and
plagioclase-phyric dacite and rhyolite. The unconformably overlying, late
early Bajocian through Tithonian Mount Jura sequence (MJS) contains a lower section
of volcanic cobble conglomerate, massive sandstone, and fissile shale, and an upper
section consisting of coarse-grained, locally-derived subaerial to shallow marine
clastic rock locally interbedded with thin flows of vesicular andesite or heterolithic
felsic tuffs and intruded by small masses of hypabyssal breccia, sills, and dikes. The
unconformably overlying Evans Peak sequence (EPS) consists of a coarsening upward
assemblage of plant-bearing, marine black shale, coarse-grained quartzose
sandstone, and chert pebble conglomerate overlain by interbedded fluvial sandstone,
shale, volcanic-cobble conglomerate, and distal ash-flow tuff. Granitic rock of
Toarcian and Tithonian age intrudes the KRS and MJS. Post-Barremian diorite intrudes
the EPS.

SKU: 2010-15 Category:

Additional information


Primary Author

Geoff Christensen



Deposit Type

Geologic Era

Geochronological Method