Carol M. Dehler
Department of Geology,Utah State University,  4505 Old Main Hill, Logan, Utah  84333  Carol.Dehler@usu.edu

carol mug shot


RESEARCH                TEACHING                ETC




                       

             
                                   











RESEARCH:

DISCIPLINES AND INTERESTS:  Sedimentology, stratigraphy, field mapping, petrography, stable-isotope geochemistry, diagenesis, current emphasis on climate, tectonics, and correlation of Neoproterozoic successions

RESEARCH PROJECTS:
NEOPROTEROZOIC WESTERN U.S.
GEOARCHEOLOGY OF COLORADO
NEW MEXICO MAPPING
DEVONIAN GREAT BASIN


STUDENT RESEARCH:

De Grey, L.D., 2005. Geology of the Swallow Canyon 7.5-minute quadrangle, Daggett County,
Utah and Moffat County, Colorado: facies analysis and stratigraphy of the Neoproterozoic eastern Uinta Mountain Group, M.S. Thesis, Idaho State University, 122 p.

Brehm, A. M., 2007.  A re-evaluation of the Jesse Ewing Canyon Formation, Uinta Mountain Group, Northeastern Utah.  Utah State University MS thesis, 232 p.

Myer, C.M., current.  Sedimentology, stratigraphy, and geochemistry of the Neoproterozoic Red Pine Shale, Uinta Mountains, northeastern Utah:  Implications for paleogeography, tectonic setting, and climate change during the Neoproterozic of western Laurentia.

Rybczynski, D., current.  Geologic mapping of the UInta Mountain Group, Goslin Mountain 7.5-minute quadrangle and vicinity.

Kingsbury, E., current (at ISU--co-advisor Paul Link).  
Geologic mapping of the Uinta Mountain Group, Kings Peak 7.5-minute quadrangle and vicinity.

Babb, S, and Daley, Lynsie, current.  Petrgraphic mapping of sandstones from the Neoproterozoic Jesse Ewing Canyon Formation, Uinta Mountains, Utah.  Undergraduate research.



STUDENTS EMPLOYED:

LAURA DEGREY--MINE GEOLOGIST, KINROSS GOLD CORP., ROUND MOUNTAIN GOLD, ROUND MOUNTAIN, NEVADA 
ANDY BREHM--PETROLEUM GEOLOGIST, ANADARKO, HOUSTON, TEXAS











NEOPROTEROZOIC WESTERN U.S.:

These projects focus on mid- to late Neoproterozoic strata and their implications for global paleoclimate, regional tectonics, ocean geochemistry, and correlation. 


carol jakes the red castle fm






Jaking the Red Castle Formation, High Uintas (left).  Carrying samples out of the Uintas with help from Thomas and Sonny the llamas.  Kings Peak, highest peak in Utah, on skyline (right).












splitNEOPROTEROZOIC UINTA MOUNTAIN GROUP, UTAH AND COLORADO

The Uinta Mountain Group(UMG)  is an amazingly understudied, 4-7 km thick succession of newly dated Proterozoic strata.  U-Pb analyses on detrital zircons has revealed a maximum depositional age of 766 Ma (Fanning and Dehler, 2005). Therefore, the UMG correlates to other dated Neoproterozoic successions in the western U.S. such as the Chuar Group.   Ongoing research in the western Uintas is focused on the Red Pine Shale--an organic-rich shale sequence (TOC)>6%).  These rocks are amenable to chemostratigraphic analyses (on organic carbon) and a detailed C-isotope curve has been generated for about 1000 m of this unit.  More traditional stratigraphic and sedimentologic studies are also underway --this unit has not been thoroughly described and paleoenvironmental interpretations remain controversial.  Correlative(?) strata on the eastern side of the range are very different and we (me and students) hypothesize that the UMG in this area represents 4-7000 m of braided stream and marginal marine deposition.  Mapping in the eastern UMG by students has resulted the subdivision  into formations, and sequence stratigraphic principles may be applicable.  We also hypothesize (me and Doug Sprinkel from the UGS) that the eastern UMG correlates with the units to the west (e.g., Red Pine Shale), but years of mapping will be necessary to test this.  Strata in the Kings Peak area in the central part of the range is amenable to sequence stratigraphy and will help to test this hypothesis.

Photo to left:  Typical outcrop of the eastern UMG (braided stream deposits).  Bushes are ~ 1 m tall.



                                                                                            






Photo to right:  Interbedded organic-rich shales and cross-bedded sandstones of the Red Pine Shale, central Uinta Mountains.  Susannah Porter for scale. 










Photo below:  Facies change in the Jesse Ewing Canyon Formation:
Neoproterozoic fan delta complex!
Laura DeGrey for scale.


jesse ewing can fm








Photomicrograph to right (2.5X):  Typical quartz arenite in the eastern Uinta Mountain Group.  
That's right, much of this Precambrian unit is NOT quartzite, but simply a well cemented sandstone.










danthe outlaw

Above:  Dan Rybczynski in his map area near the type section of the new formation of Outlaw Trail, eastern Utah.



splitCHUAR GROUP--NEOPROTEROZOIC RECORD OF THE GRAND CANYON AREA

 
This research project was part of a larger, NSF-funded project designed to answer large- and small-scale questions about the Neoproterozoic history of the Southwestern US and beyond.  The Chuar Group is a postage stamp of an outcrop belt (150 km2), but is one of the few unmetamorphosed successions of this age.  The focus of my PhD project was to characterize and interpret the Chuar Group in terms of depositional environments and basin style, as well as climate and ocean geochemistry.  Conclusions of this work reveal large-scale C-isotope shifts in organic and carbonate carbon.  These shifts coincide with lithostratigraphic and shale geochemical data and the combined datasets (see below) suggest that climate control was a player for the C-isotopic variability.  This is significant when considering the age of the Chuar Group (>742 Ma) and how it may be coeval or precursory to global-scale glaciations.  See Karlstrom et al, 2000, Porter and Knoll, 2000; Dehler et al, 2001; Timmons et al., 2001, Dehler et al., 2005 for more information.  Research on this amazing unit continues.


 





 




Figure to left:  The generation and comparison of multiple  datasets collectively indicate climate as a control on the carbon cycle in the mid-Neoproterozoic (see Dehler et al., 2005, GSAB)

    






     
 


Photo to right:  The Jupiter and Carbon Canyon members of the Chuar Group, ~400 m in view.  
Are these strata hot or what?














Photo to left:  The "brain bed"--complex stromatolites often referred to as Baicalia or Boxonia.  Note the intimate relationship with variegated siliclastic shale.  These microbial buildups likely grew when climate was dryer and sea level was relatively lower (and there was more glacial ice on the planet).  See Dehler et al., 2001 for reasoning.
.












Photo to right:  Meter-scale cycles in the Carbon Canyon Member of the Chuar Group,
interpreted to be glacioeustatic.  See Dehler et al., 2001
.



 







Photo to left:  The Sixtymile Formation unconformably overlies the Chuar Group.  Note paleovalley--is this a record of sea-level drawdown due to glaciation during the late Neoproterozoic (Sturtian)?





 splitOTHER NEOPROTEROZOIC RESEARCH:

ChUMP hypothesis (Chuar-Uinta Mountain-Pahrump groups).

This idea has been proposed by many workers.  Recent detailed work on all three of these successions will allow testing the idea that the Chuar, Uinta Mountain, and Pahrump groups, are, atleast in part, correlative and were part of a western Interior  Seaway in the Neoproterozoic. 

Correlation of mid- to late Proterozoic deposits in Utah and Idaho.  NSF $ pending.  The goal here is to answer questions about the style and timing of the rifting of the western Laurentian margin.  This project will also address the timing and style of glaciations during this time, and test the snowball Earth hypothesis.

C-isotope stratigraphy of the Toby cap carbonate.  Emmanuelle Arnaud and I are studying this cap carbonate to see if it is "like the others"...

Paleoecology and the carbon cycle prior to the Sturtian glaciation.  Susannah Porter and I are looking at fossil and stratigraphic data from mid-Neoproterozoic units to try and understand the cause(s) for ensuing low-latitude glaciations.




 





GEOARCHEOLOGY OF COLORADO:

Sourcing quartzite arifacts from the Gunnison basin, southern Colorado--NSF funded, 3 year project.  
Collaborative project with Bonnie Pitblado, Archeologist also at USU.


photomicrographphotomicrograph
 The photomicrograph on the left is from a rock sample known to have been quarried by Paleoindians.  The photomicrograph to the right is from a quartzite artifact, found in the same geographic area, and visually matched to the rock sample.  There are similarities and differences.  The question is whether any quartzite formation is distinctive enough physically and (or) chemically to allow it to be used as a fingerprint for artifact sourcing, in the same way that obsidian and chert are used.  Magnification is 2.5X in both pictures.  Geochemical techniques tested so far are INAA, ICPMS-LA, ICPMS-AD, XRF, and flourescence.  The most promising methods thusfar are ICPMS combined with petrography.  Watch for a paper in the journal Archeology for a paper by Pitblado et al. in 2008.












NEW MEXICO MAPPING:
This research is under the supervision of Mike Timmons at the New Mexico Bureau of Mines and is supported by STATEMAP.  Mapping emphasis is on the Carlsbad, New Mexico area which is dominated by Permian and Tertiary bedrock.  There are also a lot of surficial units which record the history of the Pecos River.  Other mapping projects are in the Farmington area of New Mexico where the K-T boundary is exposed.  








Teepee structure in the Permian backreef of southern New Mexico--Dark Canyon, Guadalupe Mountains.











                                                                                                                                         Joel and Sienna in front of the Permian Capitan Reef, southern New Mexico.





DEVONIAN STRATIGRAPHY OF THE GREAT BASIN:

This research is a continuation of my Master's thesis work (Northern Arizona University).  This work focuses on the Lower and Middle Devonian strata in central Idaho, the related vertebrate and invertebrate assemblages, and biostratigraphic/sequence stratigraphic correlation with other Devonian strata in the Great Basin and possibly globally.   Dave Elliott  (my MS advisor) and I are looking for students to work on some of these problems.  (See Dehler, 1995; Grader and Dehler, 1999)






TEACHING:


Above:  Return from Capitol Reef...time travel complete.



Current courses: 
GEO3200  EARTH THROUGH TIME
GEO6800  THE SEDIMENTARY RECORD






Other courses taught:  Field Methods, Field Camp, Earth Systems Science, Physical Geology,
Sedimentology and Stratigraphy, Advanced General Geology (graduate-level), Tectonics and Sedimentation (graduate-level)





ETC: