Reconstruction of Late Paleozoic Basins in Nevada: A Summary

Nevada experienced several episodes of tectonism during the late Paleozoic, resulting
in formation, filling, uplift, and exposure of several spatially overlapping basins.
Each time of exposure resulted in the formation of unconformities across much
of Nevada (e.g., Trexler and others, 2004; Cashman and others, 2010). These events
occurred between the Antler and Sonoma orogenies, thus documenting active tectonism
in Nevada throughout late Paleozoic time. It can be difficult to understand and
predict the distribution of late Paleozoic rocks in light of these syndepositional uplifts
and unconformities. Here, we present an overview of the basins and unconformities
that formed from Mississippian to early Permian time, built on a series of palinspastically
reconstructed maps.
Mississippian rocks document two significant depositional basins. The early Mississippian
Antler foreland (Kinderhookian to Meramecian) contains submarine fan
conglomerate, deep marine organic-rich shale, and carbonate shelf rocks. In contrast,
the late Mississippian (Chesterian) Antler successor basin has fluvio-deltaic conglomerate,
marine shale, and local quartz sandstone with swamp deposits containing
abundant paleosols.
Pennsylvanian to lower Permian rocks record a more segmented and complex
depositional history. In early to early middle Pennsylvanian (Morrowan to Atokan)
time, the Mississippian clastic facies are mostly replaced by a broad carbonate shelf.
In middle Pennsylvanian (Desmoinesian) time the carbonate shelf persisted in the
south but was replaced by a narrow deep marine basin in the north. By late Pennsylvanian
to early Permian (Missourian to Sakmarian) time, shallow water deposition
returned to northern and central Nevada, with a combination of sandy limestone and
coarse clastic facies. The carbonate shelf persisted into early Permian time in the
south, with development of a submarine channel complex during early middle Permian
(Sakmarian) time. The preliminary time-slice paleogeographic maps presented
here highlight regional unconformities and facies distributions in the basins for four
specific late Paleozoic time intervals. These data are critical for understanding and
predicting facies distributions to evaluate mineralization potential in late Paleozoic
strata of Nevada.
Key Words: late Paleozoic, Nevada, tectonostratigraphy, paleogeography, unconformities