Tectonostratigraphic evolution of the <em>c.</em> 780–730 Ma Beck Spring Dolomite: Basin Formation in the core of Rodinia
Emily F. Smith
Francis A. MacDonald
James L. Crowley
Eben B. Hodgin
Daniel P. Schrag
10.6084/m9.figshare.3453938.v1
https://geolsoc.figshare.com/articles/dataset/Tectonostratigraphic_evolution_of_the_em_c_em_780_730_Ma_Beck_Spring_Dolomite_Basin_Formation_in_the_core_of_Rodinia/3453938
<p>The Beck Spring Dolomite is a mixed carbonate–siliciclastic succession exposed in Death Valley, California, that was deposited
between 780 and 717 Ma. Along with its bounding units, the Horse Thief Springs Formation below and unit KP1 of the Kingston
Peak Formation above, the Beck Spring Dolomite were deposited in one of the ChUMP (Chuar–Uinta Mountains–Pahrump) basins with
subsidence commonly attributed to the nascent rifting of Rodinia. These pre-Sturtian successions preserve eukaryotic microfossil
assemblages, diverse microbialites, and large carbon isotope anomalies directly below Sturtian-age glacial deposits. Here
we present new geological mapping, measured stratigraphic sections, carbon isotope chemostratigraphy and detrital zircon geochronology
from the Beck Spring Dolomite and its bounding units. The carbon isotope excursion at the top of the Beck Spring Dolomite
has previously been attributed to meteoric diagenesis associated with karst breccias, but here we demonstrate that these breccias
are instead mass flow deposits that formed during deposition of the Kingston Peak Formation and that the carbon isotope excursion
is not only reproducible throughout the basin, but is associated with transgression rather than regression and exposure. In
addition, we refine local correlations and discuss the use of chemostratigraphic curves from these units for regional and
global correlations. The Beck Spring Dolomite was deposited during the second of three distinct basin-forming events recorded
in the Pahrump Group with basin inversion occurring between each event. The presence of syn-sedimentary faults, the character
of the lateral facies change and detrital zircon provenance analyses indicate that the Beck Spring Dolomite fringed a coeval
palaeo-high to the south in a tectonically active basin. Detrital zircon age distributions in the Beck Spring Dolomite show
sharp probability peaks at <em>c.</em> 1200, 1400 and 1800 Ma, consistent with local sources to the SW in the Mojave block rather than transcontinental rivers.
The <em>c.</em> 1800 Ma probability peak is less prominent in the KP1 samples. In addition, KP1 also records slump folding and is overlain
by an unconformity. We suggest that these features are consistent with the emergence of a local fault to the NE. Deposition
of the Beck Spring Dolomite and bounding units do not record evidence of incipient rifting of the western margin of Laurentia
but instead reflect a distinct and separate tectonothermal event.
</p>
2016-06-21 11:47:18
tectonothermal event
Pahrump Group
Basin Formation
mass flow deposits
Kingston Peak Formation
probability peaks
detrital zircon geochronology
Horse Thief Springs Formation
detrital zircon provenance analyses
Beck Spring Dolomite
eukaryotic microfossil assemblages
carbon isotope excursion
NE
Tectonostratigraphic evolution
717 Ma
stratigraphic sections
SW
Detrital zircon age distributions
Mojave block
carbon isotope anomalies
record evidence
carbon isotope chemostratigraphy
1800 Ma probability peak
KP 1
chemostratigraphic curves
KP 1 samples
karst breccias
Death Valley
facies change
basin inversion
1800 Ma
records slump
unit KP 1
Beck Spring Dolomite show
Geology