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The Role of Lake Levels in Oil Shale Distribution
However, lake systems have another control that most often plays a most important role – lake levels. Lake levels control water depth, location of depositional environments, distribution of sediment volume and lake salinity.
The depositional history of the Green River Fm illustrates the above model. Numerous lake level changes controlled the location of the lake shorelines. After an initial highstand, the lake regressed, and deeper water was restricted to the central part of the basin. During periods of low lake level, the water depth was too shallow on the lake margins for long term stratification, which is required for the anoxic state in the lower part of the water column. Yet the algal bloom persisted, as indicated by the rich oil shale deposits in the center of the basin. After the low lake level phase, water chemistry changed and salinity increased. Soon after, prominent oil shale beds were deposited throughout the basin. These beds are related both to the high lake levels and creation of brines in the lake, both enhancing long-term stratification of the lake’s water column.
Thrust Faults as a Mechanism of Attenuation in the Steep Limbs of Forced Folds
• Backthrusting from the upper detachment of a triangle zone (Sterne and Raynolds, 2001; Sterne, 2002))
• Shortening from east-west compression (Siddoway, 2002)
• Rotated growth faults (Weimer, 2004)
An analysis of this large displacement structure (associated with the Golden and Rampart Range faults), as well as several small-displacement folds, shows that the east dipping faults are part of a conjugate thrust system. The conjugate faults are a primary mechanism of attenuation as the strata are folded over the edge of an uplifted basement block. Thinning of 19 percent by this mechanism was measured in a shale unit in one outcrop.
Analyzing the orientation of thrust faults in the steep limbs of a variety of structures along the Front Range and in Central Colorado indicates that this is a common phenomenon in extended steep limbs of forced folds. These thrust faults appear to be part of an orderly system of layer-parallel extension. Thrust faults that dip into the uplifted block will place older strata over younger strata and thrust faults that dip away from the uplifted block place younger strata over older strata.
This system appears to be scale-independent, as it is observed operating on the sub-meter scale and the sub-kilometer scale. The process can create isolated, rhombic boudins or fault panels. These conjugate systems can tectonically isolate a sandstone boudin within a shale unit.
Our results suggest that the conjugate set may initiate when the strata have been tilted about 60 degrees from horizontal. With further rotation of the steep limb (even to overturned) the conjugate set is also rotated. With rotation, one of the sets becomes more favorably oriented to slip and becomes dominant.
This October, Girl Scouts from the Denver Metro area will participate in a Dinosaur Ridge Day in Morrison. This event gives them opportunities to earn badges in a number of areas, particularly in the geosciences. These young ladies will also have the opportunity to meet and talk to women geoscientists and potentially consider careers in these areas.
AWG and RMS-AEG, which are co-sponsors of this event, are looking for volunteers from all geoscience organizations in the Rocky Mountain region. About 60 volunteers will be needed, overall. Commitment will involve a half-day (or more) on the Open Ridge Day October 7.
Please consider volunteering for this important event. If you have any questions, please contact the coordinator Clare Marshall at dinodiscovery@dinoridge.org.
Moab's La Quinta Inn is located at 815 S. Main Street, 8 blocks from downtown and 1.5 blocks from the City Market, where we'll be assembling our own box lunches early Saturday and Sunday mornings (September 30 and October 1) before heading out to the field.
We've reserved a block of 25 rooms (most with single kings, but some with double queens) for Friday and Saturday, September 29-30 at $78 + tax per night for single or double occupancy. The hotel offers a heated outdoor pool, exercise and laundry facilities and, last but not least, complimentary continental breakfast in the lobby starting at 0700.
Note: Each person will be responsible for his lodging in Moab. So, while we have reserved the rooms, you will have to pay for your room yourself. Camp grounds and locations can be found on the Moab city website www.moab-utah.com
For more information on our accommodations, including directions, visit http://www.lq.com and enter Moab, UT in the search form, or call the hotel directly (435) 259-8700.
Cost for the trip is $35.00. That will cover the guidebook printing, and refreshments.
We have tried to keep costs to a minimum for the participants. So we decided that participants will have to bring their own lunches on the field trip. We will be providing water and soft drinks. There is a City Market that opens at 6:00 am, a few blocks from the La Quinta, for those who would like to buy lunch materials. We will provide a guidebook.
A few of the stops have not been included on other field trips. Some of the stops will require high clearance vehicles so if you have one, please bring it along, and plan on carpooling on the field trip days with the folks who don't have that kind of vehicle. It would be good if friends who know others that will attend the trip carpool from Denver. The trip will end between 4 and 5 p.m. on Sunday.
Deadline!
Registration payment of $35 must be received by September 25. See Form below.
return to Jeremy McCreary
6242 S. Elmira Circle East
Greenwood Village, CO 80111
Home: (303) 744-0907
Mobile: (303) 901-8280
E-mail: jeremy@cliffshade.com (jeremy@clffshade.com)
A receipt will be printed and handed out at the field trip.
Name(s): __________________________________
Phone: _______________________________
E-Mail: ________________________
Bring appropriate clothing, lunch, and water.
Number of Participants: ________ @ $35 a person
Total of all attending: $____________
For registration, send this form and your check made out to Colorado Scientific Society to Jeremy McCreary, 6242 S. Elmira Circle East, Greenwood Village, CO 80111. Deadline is Sept. 25.
Colorado Scientific Society’s regular meetings are held the 3rd Thursday of the month at the American Mountaineering Center in Golden (unless otherwise advertised). Social time begins at 6:30 p.m. and talks start at 7:00 p.m. For more information, contact Chuck Kluth at 303- 904-2939, kluth@earthlink.net
Denver Gem and Mineral Show,Sep. 15-17, 10 a.m.-6p.m.Merchandise Mart, 58th Ave. and I-25 "Minerals of South America". Admission $5. kids under 13 w/parent, free; teens, seniors 65+, $3. www.denvermineralshow.com
Denver Mining Club meets every Monday (except when noted) at Country Buffet near Bowles and Wadsworth (at 8100 W. Crestline Ave.) 11:30-1:00.Sep. 11, Nick Michael, SRK Consulting, "Financing your mine". Sep. 18, Chris Herald, Solitario Resources, "New exploration developments, Pachuca Real, Mexico (silver), Bongara, Peru (zinc), Brazil (gold). http://china-resources.net.
Denver International Petroleum Society meets the second Friday of each month at the Wynkoop Brewing Co., 18th and Wynkoop Streets. Reception begins at 11:30, luncheon at noon, program at 12:30. Make reservations (required) by leaving message at (303) 623-5396. Reservations accepted after 8 a.m. on Friday until 10:30 a.m. on Wednesday prior to the meeting. Cancellations accepted until 11:00 am Wednesday prior to the meeting. Cost: $15 for lunches; talk only is available for $2 (make checks payable to “D.I.P.S.”). Contact Keith Murray at (303) 986-8554 for information.
Denver Region Exploration Geologists’ Society (DREGS) meets in the Mutual Consolidated Water Building, 12700 West 27th Avenue, Lakewood. Social hour 6:00-7:00 p.m. Technical presentation at 7:00 p.m. Meetings are normally scheduled for the first Monday of each month. Sep. 11, Paul Schmidt, "Coarse gold and diatreme volcanic vents at the Spring Valley discoveries, Pershing County, Nevada". For information contact Jim Piper, (303) 932-0137, or the website http://www.dregs.org.
Denver Well Logging Society (DWLS) meets on the third Tuesday of each month, Sept. through May. Lunch and a technical talk at the Wynkoop Brewery begins at 11:30 a.m., 18th and Wynkoop Sts. in Denver. Subject matter usually deals with the application of well logs to oil and gas exploration. Call Eleice Wickham at 303-573-2781 for res. http://dwls.spwla.org.
Rocky Mountain Association of Geologists (RMAG) Social at 11:30, lunch at noon, talk at 12:30. Reservations are taken at 303-623-5396 until 10:30 am, Wed. before the lunch. Cancellations are taken until 11 am on Wed. at 303-573-8621. Lunch--$20 at the door. Talk only (no res)— $3. Location: Denver Petroleum Club, Anaconda Tower, 555-17th St, 37th floor. Sep. 15, Steve Natali (tentative), "Geophysics cracks the Piceance Basin". http://www.rmag.org
Colorado Mineral Society, May 6, Silent Auction, held by the, 11 a.m.-3 p.m., at Holy Shepherd Lutheran Church, 920 Kipling St., see http://www.coloradomineralsociety.org/upcomingevents.html or call 303-237-2947. No charge, all welcome.
Rocky Mountain SEPM Reception at 11:30, lunch at noon, speaker at 12:30. Reservations, Dave Uhl:303-389-5092 before noon of preceding Friday. $15.00 lunch, $3 talk only. Wynkoop Brewing Company, 1634 18th St., Denver. David.uhl@EnCana.com.
Co-AIPG 11:30-social, noon-1:30-lunch and speaker. Cost-$25. University Club, 1673 Sherman St, Denver. Reservations: Tom Cavanaugh, 303-458-5550, tcavanaugh@ascg.com.
University of Colorado at Boulder, Geological Sciences Colloquium Wednesdays, 4:00-5:30, Rm. 180.Refreshments at 3:30 on the 3rd floor. Sep. 13, Tom Marchitto, "The ocean's role in atmospheric CO2 lowering during glacial periods". Sep 27, Alan Robock, "Comparing climatic response to low and high latitude volcanic eruptions." 303-492-8141.Web page: http://www.colorado.edu/GeolSci.
Colorado State University, Dept of Geosciences,Rm. 320 Natural Resources Bldg, 4:10 pm. Sep 11, Paul Nicholson, ARAMCO, Richard Groshong, UA, "A structural model for typical hydrocarbon traps in Saudi Arabia." 970-491-5661. http://www.cnr.colostate.edu/geo/seminars/spring2005.html
Friends of Dinosaur Ridge. Fireside chats at Morrison Town Hall, 7 p.m. Web page: http://www.dinoridge.org. Admission is free, but donations are welcome. For more information contact the FODR Visitor Center at (303) 697-3466.
Colorado School of Mines, Van Tuyl Lectures Fri, from 3:00-4:00 in Berthoud Hall, Room 108. http://www.mines.edu/academic/geology.
USGS Geologic Division Colloquium. Thursdays, 1:30 , Foord Room, Building 20, Denver Federal Center. Contact: Pete Modreski, USGS, 303-202-4766, email pmodreski@usgs.gov.
For a constantly updated, online geo-calendar, visit the Colorado Geological Survey at: