Lower and Middle Devonian strata crop out on the former
stable carbonate platform that existed in the Quinn Canyon Range,
through the carbonate shelf edge in the Pancake Range, to the
carbonate slope and outer-shelf basin in the Reveille Range.
The strata of the Reveille Range record a transition from
deposition on the carbonate platform in the Lower Devonian, to
deposition at the carbonate platform margin, to deposition in the
outer-shelf basin in the Middle Devonian. Conodonts collected from
the base of the Sevy Dolomite yield a kindlei-Zone age, an indication
that the Sevy Dolomite is younger than previously recognized.
Throughout the Lower and Middle Devonian, carbonate strata
of the Pancake Range and Quinn Canyon Range were deposited on the
shallow carbonate platform. Conodonts collected from the base of the
Lower Alternating Member of the Simonson Dolomite in the Quinn
Canyon Range have a slightly older age (serotinus- to costatus Zone)
than other eastern Nevada locations.
The Lower Devonian Sevy Dolomite was deposited in a shallow
carbonate subtidal through supratidal environment and is similar in
outcrop throughout the ranges. Petrographic studies show that the
samples are lithologically and diagenetically similar, indicating a
similar intensity of dolomitization from the precursor calcareous
mudstone. The Formation classifies as bioturbated mudstone and
wackestone.
The Middle Devonian Simonson Dolomite was deposited in
shallow carbonate subtidal through supratidal environments. The
Simonson Dolomite was affected by Milankovitch Cycles, glacioeustatic
oscillations of sea level, producing a characteristic rhythmic
bedding.
The Middle Devonian Sadler Ranch Formation and Denay
Limestone are lithologically and diagenetically different from the
shallow water deposits of the Lone Mountain Dolomite, Sevy
Dolomite, and Simonson Dolomite. The Sadler Ranch Formation and
Denay Limestone were deposited at the carbonate platform edge and
on the carbonate slope and outer-shelf basin, respectively. The
Sadler Ranch Formation is dolomitized and may be classified as
fossiliferous wackestone and mudstone. The Denay Limestone is not
dolomitized and is classified as mudstone and fossiliferous grainstone
and packstone.
Dolomitization in the Paleozoic strata of Nevada is a secondary
feature, an early diagenetic replacement of strata which were
originally limestone. This replacement process was controlled by
transgressions and regressions of the shoreline. Shallow carbonate
platform deposits (shelfal and tidal-flat) are dolomitized, whereas
deep water outer-shelf basin and slope deposits are not. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34319 |
| Date | 21 May 1996 |
| Creators | Nelson, Storr L. |
| Contributors | Niem, Alan R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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