A Mid-Mesozoic Breccia from the Coast of Labrador

1975 ◽  
Vol 12 (1) ◽  
pp. 44-51 ◽  
Author(s):  
A. F. King ◽  
N. J. McMillan
Keyword(s):  
Vitrinite Reflectance ◽  
Early Jurassic ◽  
Labrador Sea ◽  
Igneous Activity ◽  
Shallow Seas

A unique occurrence of Mesozoic breccia cut by lamprophyric-carbonatite dikelets, near Makkovik, Labrador is interpreted to relate to the opening of the Labrador Sea. The breccia has been dated by nannofossils; vitrinite reflectance studies show that some time during or after deposition the rock was heated to at least 170 °C. It is suggested that shallow seas extended westward beyond the present Labrador Marginal Trough during early Jurassic time and that the period of late alkaline igneous activity is related to the rifting between Greenland and Labrador that commenced about the middle of the Mesozoic Era.

40Ar–39Ar dating of alkali basaltic dykes along the southwest coast of Greenland: Cretaceous and Tertiary igneous activity along the eastern margin of the Labrador Sea

1999 ◽  
pp. 19-29 ◽  
Author(s):  
Lotte Melchior Larsen ◽  
David C. Rex ◽  
W. Stuart Watt ◽  
Philip G. Guise
Keyword(s):  
Alkali Basalt ◽  
Dyke Swarm ◽  
Labrador Sea ◽  
Precambrian Basement ◽  
Stress Regime ◽  
Southwest Coast ◽  
Eastern Margin ◽  
Step Heating ◽  
Igneous Activity ◽  
Break Up

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Melchior Larsen, L., Rex, D. C., Watt, W. S., & Guise, P. G. (1999). 40Ar–39Ar dating of alkali basaltic dykes along the southwest coast of Greenland: Cretaceous and Tertiary igneous activity along the eastern margin of the Labrador Sea. Geology of Greenland Survey Bulletin, 184, 19-29. https://doi.org/10.34194/ggub.v184.5227 _______________ A 380 km long coast-parallel alkali basalt dyke swarm cutting the Precambrian basement in south-western Greenland has generally been regarded as one of the earliest manifestations of rifting during continental stretching prior to break-up in the Labrador Sea. Therefore, the age of this swarm has been used in models for the evolution of the Labrador Sea, although it has been uncertain due to earlier discrepant K–Ar dates. Two dykes from this swarm situated 200 km apart have now been dated by the 40Ar–39Ar step-heating method. Separated biotites yield plateau ages of 133.3 ± 0.7 Ma and 138.6 ± 0.7 Ma, respectively. One of the dykes has excess argon. Plagioclase separates confirm the biotite ages but yield less precise results. The age 133– 138 Ma is earliest Cretaceous, Berriasian to Valanginian, and the dyke swarm is near-coeval with the oldest igneous rocks (the Alexis Formation) on the Labrador shelf. A small swarm of alkali basalt dykes in the Sukkertoppen (Maniitsoq) region of southern West Greenland was also dated. Two separated kaersutites from one sample yield an average plateau age of 55.2 ± 1.2 Ma. This is the Paleocene–Eocene boundary. The swarm represents the only known rocks of that age within several hundred kilometres and may be related to changes in the stress regime during reorganisation of plate movements at 55 Ma when break-up between Greenland and Europe took place.

Optical properties of organic matter in relation to thermal gradients and structural deformation

1985 ◽  
Vol 315 (1531) ◽  
pp. 157-186 ◽  
Keyword(s):  
Optical Properties ◽  
Static Pressure ◽  
Vitrinite Reflectance ◽  
Structural Deformation ◽  
Physical Parameters ◽  
Low Grade ◽  
Organic Petrology ◽  
Geological Conditions ◽  
Igneous Activity ◽  
General Response

The general response of macerals to the coalification process, the effectiveness of organic geochemical and petrological parameters as estimators of coalification and the applicability of different microscopical parameters in the assessment of rank are reviewed. The central role of vitrinite reflectance as the most widely used estimator of coalification from brown coals to the low -grade metamorphic zone is established on the basis of its relatively uniform variation with rank, specificity, ease and rapidity of measurement and cheapness. Factors influencing the optical properties ofvitrinites are considered. Temperature has the dominant influence in modifying optical properties with rank, but time, static pressure and stress can all have significant influences upon the course of optical properties, depending upon particular geological conditions. Static pressure has a retarding effect on the coalification process, but it is also responsible for creating increasing anisotropy within the condensing aromatic structures as rank rises. Hydrostatic pressures and pore pressures can contribute to the overpressuring of sediments, thus affecting their thermal conductivities and consequently the rate of coalification. Stress is responsible for the development of biaxicity in the reflectance indicatrix. Fast and high levels of heating from igneous bodies cause textural effects on vitrinites as a result of carbonization that are quite different from those of coalification. Recognizing these different influences upon the optical properties of vitrinites, examples are given of the use and application of vitrinite reflectance in the preparation of rank maps, in the burial histories of basins, in the timing of coalification in relation to orogenesis and igneous activity and in the zones of anchimetamorphism and low-grade metamorphism. Consideration is also given to the problem of ‘provincialism ’ in correlations between chemical and physical parameters and to the future development of optical studies in organic petrology and their relation to organic geochemical investigations.

Triassic olivine-normative diabase from Northumberland Strait, eastern Canada: implications for continental rifting

1986 ◽  
Vol 23 (7) ◽  
pp. 1013-1021 ◽  
Author(s):  
Georgia Pe-Piper ◽  
Lubomir F. Jansa
Keyword(s):  
Early Jurassic ◽  
Igneous Rocks ◽  
Late Triassic ◽  
Geochemical Evolution ◽  
High Alumina ◽  
Continental Rifting ◽  
Eastern Canada ◽  
Mafic Rocks ◽  
Eu Anomaly ◽  
Igneous Activity

Two intervals of mafic igneous rocks were encountered within a Silurian to Carboniferous sequence in an exploratory offshore well located in the Gulf of St. Lawrence, eastern Canada. Geochemical and radiometric analyses show that the lower mafic rocks are Early Silurian continental tholeiite lavas, with their radiogenic clock thermally reset during the Late Devonian. The upper igneous interval consists of several dikes of high-alumina diabase characterized by flat, relatively unenriched REE spectra and a positive Eu anomaly. This diabase resembles olivine tholeiites. Two K/Ar dates suggest a Late Triassic age for these intrusions. The dike composition differs from that of known Late Triassic and Early Jurassic continental tholeiites nearby in Nova Scotia, which are associated with a late stage of continental rifting. The Triassic – Early Jurassic igneous activity shows a pattern of geochemical evolution that we relate to mantle upwelling.

MATURATION PATTERNS IN THE PERTH BASIN

1979 ◽  
Vol 19 (1) ◽  
pp. 94 ◽  
Author(s):  
A. J. Kantsler ◽  
A. C. Cook
Keyword(s):  
Vitrinite Reflectance ◽  
Upper Jurassic ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Geothermal Gradients ◽  
The North ◽  
Reservoir Conditions ◽  
Igneous Activity ◽  
Hydrocarbon Deposits ◽  
Very High

Vitrinite reflectance data from wells drilled in the Perth Basin show that major variations exist in the pattern of rank distribution within the basin. Generally, rank gradients are low and near linear, but some wells show curvature of the rank profile in the Early Jurassic and Triassic parts of their sections. Curvature of the rank profile is generally associated with a shallow depth to basement, but the presence of very high ranks in parts of the Permian section on the Beagle Ridge suggests that a Permian to Jurassic thermal event associated with local igneous activity or the initiation of rifting, or both, may also be a controlling factor. Low, linear rank gradients from parts of the basin such as the Bunbury Trough and the thick Upper Jurassic sections of some of the deeper sub-basins are taken to indicate that low geothermal gradients have operated since the Permian,in the former instance and certainly since the Jurassic in the latter. Such conditions imply slow generation of hydrocarbons.Higher geothermal gradients and rank gradients in parts of the basin as in the north Dandaragan Trough and Vlaming Sub-basin imply enhanced hydrocarbon generation, particularly as calculated palaeotemperatures indicate that the advent of higher geothermal gradients is likely to have been relatively recent. Potential source rocks occur throughout the basin and provided that suitable structural and reservoir conditions can be delineated, the prospects of discovering more commercial hydrocarbon deposits are high.

Paleo-Heat Flow Anomaly at the End of Middle Permian in NE Sichuan Basin, SW China: Did an Ocean Trough Exist?

2013 ◽  
Vol 734-737 ◽  
pp. 139-146
Author(s):  
Chuan Qing Zhu ◽  
Song Rao ◽  
Sheng Biao Hu
Keyword(s):  
Heat Flow ◽  
Sichuan Basin ◽  
Vitrinite Reflectance ◽  
Middle Permian ◽  
Early Triassic ◽  
Late Permian ◽  
Sw China ◽  
Northeastern Sichuan ◽  
Igneous Activity ◽  
Northeastern Sichuan Basin

It is an issue whether the Kaijiang-Liangping area (in the northeastern Sichuan Basin, SW China) was a controversial ocean trough during Changxing age in the late Permian-early Triassic. Some vitrinite reflectance (Ro) profiles from wells in the northeastern Sichuan Basin show obvious breaks, and the breaks are coincident with the boundary between the middle Permian and late Permian. Based on the Ro data, the heat flow history in the northeastern Sichuan Basin was reconstructed. The result shows that the heat flow reached its peak value at the end of middle Permian (~260Ma). The spatiotemporal feature of the heat flow evolution is not in agreement with the fact that there was a Kaijiang-Liangping Trough existing in the late-Permian to early Triassic. The palaeo-heat flow anomaly was, in fact, a response to the igneous activity in late middle Permian.

The Influences of the Rank of Coal on Methane Sorption Capacity in Coals/Wpływ Rzędu Węgla Na Pojemność Sorpcyjną Metanu W Węglach

2014 ◽  
Vol 59 (2) ◽  
pp. 509-516
Author(s):  
Andrzej Olajossy
Keyword(s):  
Sorption Capacity ◽  
Coalbed Methane ◽  
Vitrinite Reflectance ◽  
Sorption Isotherms ◽  
Volatile Matter ◽  
Low Rank ◽  
Hard Coal ◽  
Petrographic Composition ◽  
Methane Sorption ◽  
Indian Coals

Abstract Methane sorption capacity is of significance in the issues of coalbed methane (CBM) and depends on various parameters, including mainly, on rank of coal and the maceral content in coals. However, in some of the World coals basins the influences of those parameters on methane sorption capacity is various and sometimes complicated. Usually the rank of coal is expressed by its vitrinite reflectance Ro. Moreover, in coals for which there is a high correlation between vitrinite reflectance and volatile matter Vdaf the rank of coal may also be represented by Vdaf. The influence of the rank of coal on methane sorption capacity for Polish coals is not well understood, hence the examination in the presented paper was undertaken. For the purpose of analysis there were chosen fourteen samples of hard coal originating from the Upper Silesian Basin and Lower Silesian Basin. The scope of the sorption capacity is: 15-42 cm3/g and the scope of vitrinite reflectance: 0,6-2,2%. Majority of those coals were of low rank, high volatile matter (HV), some were of middle rank, middle volatile matter (MV) and among them there was a small number of high rank, low volatile matter (LV) coals. The analysis was conducted on the basis of available from the literature results of research of petrographic composition and methane sorption isotherms. Some of those samples were in the form (shape) of grains and others - as cut out plates of coal. The high pressure isotherms previously obtained in the cited studies were analyzed here for the purpose of establishing their sorption capacity on the basis of Langmuire equation. As a result of this paper, it turned out that for low rank, HV coals the Langmuire volume VL slightly decreases with the increase of rank, reaching its minimum for the middle rank (MV) coal and then increases with the rise of the rank (LV). From the graphic illustrations presented with respect to this relation follows the similarity to the Indian coals and partially to the Australian coals.

Oil to Source Rock Correlation Using Biomarker Data Through Pattern Matching and Fingerprinting Analysis in “Kitkat” Field, Jabung Block, South Sumatra Basin

2020 ◽  
Author(s):  
S., R. Muthasyabiha
Keyword(s):  
Pattern Matching ◽  
Source Rock ◽  
Vitrinite Reflectance ◽  
Hydrocarbon Exploration ◽  
Source Rocks ◽  
Maturity Level ◽  
Fingerprinting Analysis ◽  
Kerogen Type ◽  
Oil Characteristics ◽  
Biomarker Data

Geochemical analysis is necessary to enable the optimization of hydrocarbon exploration. In this research, it is used to determine the oil characteristics and the type of source rock candidates that produces hydrocarbon in the “KITKAT” Field and also to understand the quality, quantity and maturity of proven source rocks. The evaluation of source rock was obtained from Rock-Eval Pyrolysis (REP) to determine the hydrocarbon type and analysis of the value of Total Organic Carbon (TOC) was performed to know the quantity of its organic content. Analysis of Tmax value and Vitrinite Reflectance (Ro) was also performed to know the maturity level of the source rock samples. Then the oil characteristics such as the depositional environment of source rock candidate and where the oil sample develops were obtained from pattern matching and fingerprinting analysis of Biomarker data GC/GCMS. Moreover, these data are used to know the correlation of oil to source rock. The result of source rock evaluation shows that the Talangakar Formation (TAF) has all these parameters as a source rock. Organic material from Upper Talangakar Formation (UTAF) comes from kerogen type II/III that is capable of producing oil and gas (Espitalie, 1985) and Lower Talangakar Formation (LTAF) comes from kerogen type III that is capable of producing gas. All intervals of TAF have a quantity value from very good–excellent considerable from the amount of TOC > 1% (Peters and Cassa, 1994). Source rock maturity level (Ro > 0.6) in UTAF is mature–late mature and LTAF is late mature–over mature (Peters and Cassa, 1994). Source rock from UTAF has deposited in the transition environment, and source rock from LTAF has deposited in the terrestrial environment. The correlation of oil to source rock shows that oil sample is positively correlated with the UTAF.

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