Regional-scale variation of characteristics of hydrocarbon fluid inclusions and thermal conditions along the Paleozoic Laurentian continental margin in eastern Quebec, Canada

2000 ◽  
Vol 48 (3) ◽  
pp. 193-211 ◽  
Author(s):  
G. Chi
Keyword(s):  
Continental Margin ◽  
Fluid Inclusions ◽  
Regional Scale ◽  
Thermal Conditions ◽  
Hydrocarbon Fluid ◽  
Scale Variation

Characterization of hydrocarbon fluid inclusions by infra-red and fluorescence microspectrometry

1990 ◽  
Vol 54 (375) ◽  
pp. 311-324 ◽  
Author(s):  
Nicole Guilhaumou ◽  
Nathalie Szydlowskii ◽  
Bernard Pradier
Keyword(s):  
Fluid Inclusions ◽  
Aromatic Hydrocarbons ◽  
Fluorescence Emission ◽  
Liquid Hydrocarbon ◽  
Fluorescence Emission Spectrum ◽  
Hydrocarbon Fluid ◽  
Liquid Phases ◽  
Infra Red ◽  
Aliphatic And Aromatic Hydrocarbons

AbstractLiquid-hydrocarbon-bearing fluid inclusions have often been described associated with petroleum occurrences and diagenetic sediments. Infra-red microspectrometry allows characterization of fluid inclusions greater than 20 µm by establishing the presence of aliphatic and aromatic hydrocarbons as well as associated H2O, CO2 and CH4. Semi-quantitative analyses have been made by focussing on gaseous and liquid phases separately. Some CH2/CH3 and CO2/CH4 ratios have been determined by this method.Fluorescence microspectrometry permits precise measurements of the fluorescence emission spectrum of chromophore-bearing organic phases (essentially aromatic hydrocarbons) in fluid inclusions greater than 10 µm. Such a spectrum is a function of both the gross composition of the trapped oil and its thermal history.Both of these methods lead to the in situ characterization of hydrocarbon fluid inclusions. They are useful in providing a quantifiable distinction between different oil generations trapped during mineral growth in diagenetic and epigenetic minerals.

scholarly journals Large regional-scale variation in C3/C4 distribution pattern of Inner Mongolia steppe is revealed by grazer wool carbon isotope composition

2009 ◽  
Vol 6 (5) ◽  
pp. 795-805 ◽  
Author(s):  
K. Auerswald ◽  
M. H. O. M. Wittmer ◽  
T. T. Männel ◽  
Y. F. Bai ◽  
R. Schäufele ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Inner Mongolia ◽  
Isotope Composition ◽  
Regional Scale ◽  
C4 Plants ◽  
Entire Area ◽  
Community Biomass ◽  
Farm Scale ◽  
Sheep Wool ◽  
Scale Variation

Abstract. This work explored the spatial variation of C3/C4 distribution in the Inner Mongolia, P. R. China, steppe by geostatistical analysis of carbon isotope data of vegetation and sheep wool. Standing community biomass (n=118) and sheep wool (n=146) were sampled in a ~0.2 Mio km2 area. Samples from ten consecutive years (1998–2007) were obtained. Community biomass samples represented the carbon isotopic composition of standing vegetation on about 1000 m2 ("community-scale"), whereas the spatio-temporal scale of wool reflected the isotope composition of the entire area grazed by the herd during a 1-yr period (~5–10 km2, "farm-scale"). Pair wise sampling of wool and vegetation revealed a 13C-enrichment of 2.7±0.7‰ (95% confidence interval) in wool relative to vegetation, but this shift exhibited no apparent relationships with environmental parameters or stocking rate. The proportion of C4 plants in above-ground biomass (PC4, %) was estimated with a two-member mixing model of 13C discrimination by C3 and C4 vegetation (13Δ3 and 13Δ4, respectively), in accounting for the effects of changing 13C in atmospheric CO2 on sample isotope composition, and of altitude and aridity on 13Δ3. PC4 averaged 19%, but the variation was enormous: full-scale (0% to 100%) at community-scale, and 0% to 85% at farm-scale. The farm-scale variation of PC4 exhibited a clear regional pattern over a range of ~250 km. Importantly PC4 was significantly higher above the 22°C isotherm of the warmest month, which was obtained from annual high-resolution maps and averaged over the different sampling years. This is consistent with predictions from C3/C4 crossover temperature of quantum yield or light use efficiency in C3 and C4 plants. Still, temperature gradients accounted for only 10% of the farm-scale variation of PC4, indicating that additional factors control PC4 on this scale.

scholarly journals Thermal conditions during deformation of partially molten crust from TitaniQ geothermometry: rheological implications for the anatectic domain of the Araçuaí belt, eastern Brazil

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1223-1242 ◽  
Author(s):  
G. C. G. Cavalcante ◽  
A. Vauchez ◽  
C. Merlet ◽  
M. Egydio-Silva ◽  
M. H. Bezerra de Holanda ◽  
...  
Keyword(s):  
Partial Melting ◽  
Flow Direction ◽  
Regional Scale ◽  
Thermal Conditions ◽  
Middle Crust ◽  
Low Viscosity ◽  
Lateral Extrusion ◽  
Eastern Brazil ◽  
Gravity Driven ◽  
Gravity Driven Flow

Abstract. During the Neoproterozoic orogeny, the middle crust of the Araçuaí belt underwent widespread partial melting. At the regional scale, this anatectic domain is characterized by a progressive rotation of the flow direction from south to north, suggesting a 3-D deformation of the anatectic middle crust. To better determine whether melt volumes present in the anatectic middle crust of the Araçuaí orogen were large enough to allow a combination of gravity-driven and convergence-driven deformation, we used the titanium-in-quartz (TitaniQ) geothermometer to estimate the crystallization temperatures of quartz grains in the anatectic rocks. When possible, we compared these estimates with thermobarometric estimates from traditional exchange geothermobarometers applied to neighboring migmatitic kinzigites. TitaniQ temperatures range from 750 to 900 °C, suggesting that quartz starts crystallizing at minimum temperatures of ≥ 800 °C. These results, combined with the bulk-rock chemical composition of diatexites, allows the estimation of a minimum of ~ 30% melt and a corresponding viscosity of ~ 109–1010 Pa s. Such a minimum melt content and low viscosity are in agreement with interconnected melt networks observed in the field. Considering that these characteristics are homogeneous over a wide area, this supports the finding that the strength of the middle crust was severely weakened by extensive partial melting, making it prone to gravity-driven flow and lateral extrusion.

Small differences in ombrotrophy control regional-scale variation in methane cycling among Sphagnum-dominated peatlands

2018 ◽  
Vol 139 (2) ◽  
pp. 155-177 ◽  
Author(s):  
C. Zalman ◽  
J. K. Keller ◽  
M. Tfaily ◽  
M. Kolton ◽  
L. Pfeifer-Meister ◽  
...  
Keyword(s):  
Regional Scale ◽  
Methane Cycling ◽  
Scale Variation

Geology and petroleum prospectivity of the deepwater Otway and Sorell basins: new insights from an integrated regional study

2011 ◽  
Vol 51 (2) ◽  
pp. 692 ◽  
Author(s):  
Andrew Stacey ◽  
Cameron Mitchell ◽  
Goutam Nayak ◽  
Heike Struckmeyer ◽  
Michael Morse ◽  
...  
Keyword(s):  
Continental Margin ◽  
Regional Scale ◽  
Rift System ◽  
Aeromagnetic Data ◽  
Regional Study ◽  
Sequence Stratigraphic ◽  
Petroleum Systems ◽  
Tectonic History ◽  
Complex Structural ◽  
Potential Field Modelling

The frontier deepwater Otway and Sorell basins lie offshore of southwestern Victoria and western Tasmania at the eastern end of Australia’s Southern Rift System. The basins developed during rifting and continental separation between Australia and Antarctica from the Cretaceous to Cenozoic. The complex structural and depositional history of the basins reflects their location in the transition from an orthogonal–obliquely rifted continental margin (western–central Otway Basin) to a transform continental margin (southern Sorell Basin). Despite good 2D seismic data coverage, these basins remain relatively untested and their prospectivity poorly understood. The deepwater (> 500 m) section of the Otway Basin has been tested by two wells, of which Somerset–1 recorded minor gas shows. Three wells have been drilled in the Sorell Basin, where minor oil shows were recorded near the base of Cape Sorell–1. As part of the federal government-funded Offshore Energy Security Program, Geoscience Australia has acquired new aeromagnetic data and used open file seismic datasets to carry out an integrated regional study of the deepwater Otway and Sorell basins. Structural interpretation of the new aeromagnetic data and potential field modelling provide new insights into the basement architecture and tectonic history, and highlights the role of pre-existing structural fabric in controlling the evolution of the basins. Regional scale mapping of key sequence stratigraphic surfaces across the basins, integration of the regional structural analysis, and petroleum systems modelling have resulted in a clearer understanding of the tectonostratigraphic evolution and petroleum prospectivity of this complex basin system.

scholarly journals Towards a palaeoclimatic model of rock-glacier formation in the Swiss Alps

2000 ◽  
Vol 31 ◽  
pp. 281-286 ◽  
Author(s):  
Regula Frauenfelder ◽  
Andreas Kääb
Keyword(s):  
Regional Scale ◽  
Thermal Conditions ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Swiss Alps ◽  
Inventory Analysis ◽  
Rock Glacier ◽  
Altitudinal Distribution ◽  
Polymorphic Type ◽  
Rock Glaciers

AbstractClimate and its long-term variability govern ground thermal conditions, and for this reason represent one of the most important impacts on creeping mountain permafrost. The decoding and better understanding of the present-day morphology and distribution of rock glaciers opens up a variety of insights into past and present environmental, especially climatic, conditions on a local to regional scale. The present study was carried out in the Swiss Alps using two different approaches: (1) kinematic analysis of specific active rock glaciers, and (2) description of the altitudinal distribution of relict rock glaciers. Two theoretical shape concepts of active rock-glacier morphology were derived’ a"monomorphic" type, representing presumably undisturbed, continuous development over several millennia and a ˚polymorphic" type, reflecting a system of (possibly climatically affected) individual creep streams several centuries old. The topoclimatic-based inventory analysis indicated an average temperature increase at relict rock-glacier fronts of approximately +2°C since the time of their decay, which is a sign of rock-glacier ages reaching back to the Alpine Late Glacial. The temperature difference of some tenths of a degree Celsius found for active/inactive rock glaciers is typical for the bandwidth of Holocene climate variations. These results confirm the importance of Alpine rock glaciers as highly sensitive indicators of past temperature evolution.

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