34S and 18O abundances differentiate Upper Cambrian and Lower Devonian gypsum-bearing units, District of Mackenzie, N.W.T.—an update

1982 ◽  
Vol 19 (6) ◽  
pp. 1246-1254 ◽  
Author(s):  
Robert O. van Everdingen ◽  
M. Asif Shakur ◽  
H. Roy Krouse
Keyword(s):  
Lower Devonian ◽  
Sulfur Isotope ◽  
Thrust Fault ◽  
Upper Cambrian ◽  
Rock Formation ◽  
Opposite Trend ◽  
The Mean ◽  
Rock Strata ◽  
Sulfur Isotope Data ◽  
Isotope Analyses

Previous sulfur isotope data for the Lower Devonian Bear Rock Formation and the Upper Cambrian Saline River Formation in the District of Mackenzie, N.W.T. have been supplemented by additional sulfur isotope analyses as well as δ18O determinations on sulfates from outcrops, drill cuttings, and cores. Whereas the mean δ34S value for the Bear Rock Formation is lower than that of the Saline River Formation (+17.8 ± 1.8‰ versus +29.7 ± 2.2‰), the opposite trend was found for the mean δ18O values (+15.6 ± 1.0‰ versus +13.0 ± 1.5‰). The new data confirm that, for all samples analysed, there is no overlap between δ34S values for the two formations, while the δ18O data display some overlap. The earlier δ34S data for samples from an evaporitic section on the northeast side of the Norman Range (originally mapped as consisting entirely of Saline River Formation) indicated the presence of a thrust fault in the section, with Saline River strata overlying Bear Rock strata. The δ18O data for those samples, which fortuitously fall into two non-overlapping groups, confirm the earlier conclusions based on the δ34S data and allow us to define the position of the thrust-fault contact somewhat more closely.

Stratigraphic differentiation by sulfur isotopes between Upper Cambrian and Lower Devonian gypsum-bearing units, District of Mackenzie, N.W.T.

1977 ◽  
Vol 14 (12) ◽  
pp. 2790-2796 ◽  
Author(s):  
Robert O. van Everdingen ◽  
H. Roy Krouse
Keyword(s):  
Standard Deviation ◽  
Lower Devonian ◽  
Sulfur Isotope ◽  
Sulfur Isotopes ◽  
Lower Portion ◽  
Main Thrust ◽  
Upper Cambrian ◽  
Rock Formation ◽  
Rock Strata ◽  
Isotope Analyses

Sulfur isotope analyses of gypsum in outcrop and subsurface samples from the Lower Devonian Bear Rock Formation gave δ34S values ranging from + 10.3 to + 21.8‰ (mean + 16.1‰, standard deviation 2.85‰); samples from the Upper Cambrian Saline River Formation gave δ34S values ranging from + 24.7 to + 40.2‰ (mean + 30.3‰, standard deviation 3.65‰). The lower portion of one outcrop section of 532 ft (162.2 m) on the northeast side of the Norman Range (Franklin Mountains), mapped as Saline River Formation, showed anomalous δ34S values (+ 10.3–+ 18.7‰), suggesting correlation with the Bear Rock Formation. It is likely that at least 97 ft (29.6 m) of Bear Rock strata are present in this section, overlain by a maximum of 435 ft (132.6 m) of gypsiferous Saline River strata that form the base of the main thrust plate of the Norman Range in this locality.

Carbon, oxygen, and sulfur isotope compositions and model of the Silurian rock formation in northwestern Belarus

2018 ◽  
Vol 53 (1) ◽  
pp. 1-13 ◽  
Author(s):  
A. A. Makhnach ◽  
S. A. Kruchek ◽  
B. G. Pokrovsky ◽  
G. D. Strel’tsova ◽  
O. V. Murashko ◽  
...  
Keyword(s):  
Sulfur Isotope ◽  
Rock Formation

scholarly journals Geochemical description and sulfur isotope data for Shahrak intrusive body and related Fe‐mineralization (east Takab), northwest Iran

Island Arc ◽  
2020 ◽  
Vol 29 (1) ◽  
Author(s):  
Ali A. Sepahi ◽  
Hamid Ghoreishvandi ◽  
Mohammad Maanijou ◽  
Teruyuki Maruoka ◽  
Hamed Vahidpour
Keyword(s):  
Sulfur Isotope ◽  
Intrusive Body ◽  
Isotope Data ◽  
Northwest Iran ◽  
Sulfur Isotope Data

scholarly journals The Influence of Coupled Thermomechanical Processes on the Pressure and Temperature due to Cold Water Injection into Multiple Fracture Zones in Deep Rock Formation

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
Bruno Figueiredo ◽  
Chin-Fu Tsang ◽  
Auli Niemi
Keyword(s):  
Pore Pressure ◽  
Cold Water ◽  
Injection Pressure ◽  
Initial Permeability ◽  
Fracture Zones ◽  
Maximum Increase ◽  
Rock Formation ◽  
Deep Rock ◽  
The Mean ◽  
Fluid Pore Pressure

A technique to produce geothermal energy from deep rock formations at elevated temperatures consists of drilling two parallel deep boreholes, the second of which is directed so as to intersect a series of fractures produced by hydraulic fracturing in the first borehole. Then, the first borehole is used for injection of cold water and the second used to produce water that has been heated by the deep rock formation. Some very useful analytical solutions have been applied for a quick estimate of the water outlet temperature and injection/production pressures in this enhanced geothermal system (EGS), but they do not take into account the influence of thermomechanical and hydromechanical effects on the time evolutions of the pressure and temperature. This paper provided help for the engineering design of the EGS based on these analytical solutions, by evaluating the separate influences of the thermal (T), hydromechanical (HM), thermo-hydro-mechanical (THM) effects on the fluid pore pressure and temperature. A thermo-hydro-mechanical (THM) model was developed to simulate the heat extraction from multiple preexisting fracture zones in the hot rock formation, by considering permeability changes due to the injection pressure as a function of changes in the mean effective stress. It was found that the thermal effects (without coupling with mechanical effects) led to a decrease of the transmissivity of the fracture zones and a consequent increase in the injection pressure, by a maximum factor of 2. When the temperature is constant, the influence of the hydromechanical effects on the fluid pore pressure was found to be negligible, because in such scenario, the variation of the mean effective stress was 3 MPa, which was associated with a maximum increase in the initial permeability of the fracture zone only by a factor of 1.2. Thermo-hydro-mechanical effects led to a maximum increase in the permeability of the fracture zones of approximately 10 times the initial value, which was associated with a decrease in the fluid pore pressure by a maximum factor of 1.25 and 2, when hydrological and thermohydrological effects were considered, respectively. Changes in temperature were found not to be affected significantly by the thermomechanical and hydromechanical effects, but by the flow rate in the fracture zones. A sensitivity analysis was conducted to study the influence of the number, the initial permeability, the elastic modulus and the residual porosity of the fracture zones, and the elastic modulus of the confining intact rock, on the simulation results. The results were found to be the most sensitive to the number and the initial permeability of the fracture zones.

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