Maturation thermique de la matière organique dans un bassin du Paléozoïque inférieur, basses-terres du Saint-Laurent, Québec, Canada

1991 ◽  
Vol 28 (7) ◽  
pp. 1019-1030 ◽  
Author(s):  
Y. Héroux ◽  
R. Bertrand
Keyword(s):  
Hydrothermal Activity ◽  
Contact Metamorphism ◽  
Thermal Maturation ◽  
Solid Bitumen ◽  
North East ◽  
The North ◽  
Tectonic Transport ◽  
Connecticut Valley ◽  
Domain 3 ◽  
Locally Fine

The organic matter (OM) sampled in 15 oil exploration wells and 102 outcrops of Cambrian-Ordovician rocks in the St. Lawrence Lowlands consists of zooclasts (chitinozoans, graptolites, and scolecodonts) and solid bitumen (mainly pyrobitumen). The reflectance of pyrobitumen, transformed in vitrinite-equivalent (Ro-Std-B), indicates that the upper part of the platform sequence is mature (condensate zone) in the Québec area, but overmature in the Montréal area.The platform is divided into three domains based on optical texture of OM and types of bitumen: domain 1, south of Montréal, contains a highly reflecting and coked pyrobitumen showing alteration rims; domain 3, east of Trois-Rivières, contains low-reflecting, late solid bitumen commonly associated with oil impregnations; domain 2, located midway, contains a pyrobitumen with moderate reflectance and, locally, fine mosaic texture. The thermal maturation in the autochthonous sequences of the St. Lawrence Lowlands and in the Appalachian allochthons increases from the north-east toward the south-west and in the direction of the Appalachian belt. In wells, the gradient of Ro-Std-B with depth decrease from the autochthonous zone toward the Appalachian belt, and is inversely related with thickness of the sequences. Isoreflectance values parallel the outline of the Chambly–Fortierville Syncline in the central and eastern parts of the basin. Consequently, thermal maturation predates folding. Reflectance jumps observed between the Lowlands and the first Appalachian overthrusts, and observed when crossing Logan's Line, demonstrate that the maximum burial of Appalachian sequences predates the tectonic transport. The Ro-Std-B in allochthonous zones shows higher values in the St-Francis River cross-section than in structural equivalent units of the Québec area. Therefore the increase of thermal maturation observed from the northeast toward the southwest, in the St. Lawrence Lowlands, is also developed in the Appalachian allochthonous units. A post-Taconic regional thermal event explains this similarity in both autochthonous and allochthonous sequences, with the sequences of the Connecticut Valley – Gaspé Synclinorium being the most thermally mature.Zones of highest thermal maturation, locally observed in the Montréal area, are explained by (i) hydrothermal activity (Ro-Std = 3–4%), accounted for by sulfate and sulfide mineralization (Ba, Zn, Pb) and by (ii) contact metamorphism, related to alkaline intrusions (Ro-Std-B = 13%). The contact metamorphism is restricted to aureoles less than 5 km wide around the Monteregian alkaline intrusions, but the hydrothermal alteration, apparently not related to contact metamorphism, covers an area of 10 km around mineralized domains.

scholarly journals Mode of Occurrence of Nepheline Syenites in the Gorkha-Ampipal Area, Central Nepal Lesser Himalaya

1995 ◽  
Vol 11 ◽  
Author(s):  
M. R. Dhital
Keyword(s):  
Nepheline Syenite ◽  
Hot Springs ◽  
Country Rock ◽  
Hanging Wall ◽  
Hydrothermal Activity ◽  
Contact Metamorphism ◽  
Low Grade ◽  
Main Central Thrust ◽  
The North ◽  
Ore Minerals

In the Gorkha-Ampipal area, low-grade metamorphic rocks of the Kuncha Formation are delimited in the north by the Masel Thrust. The Kuncha Formation is characterised by doubly-plunging, en-echelon types of noncylindrical folds which are 2 to 20 km long (essentially in NW-SE direction), and have wavelengths of a few km. Mineral and stretching lineations are gently plunging due NNE or SSW. The hanging wall of the Masel Thrust is represented by garnet-biotite schists and gneisses. The schists and gneisses make up a steeply northward dipping homocline. In contrast to the rocks of the footwall, they are generally gently dipping and constitute several mesoscopic folds. Further north, the homocline is discordantly overlain by the intensely deformed unit of phyllites, graphitic schists, marbles, crystalline limestones, and calcareous quartzites. The Main Central Thrust sharply overrides the latter unit and brings with it gently northward dipping kyanite-garnet-biotite schists, quartzites, feldspathic schists, and mylonitic gneisses. There are several nepheline syenite intrusive bodies in the Kuncha Formation in the vicinity of the villages Harmi Bhnnjyang, Ampipal, Chanp Bhanjyang, Bhulbhule Khar, and Luintel Bhanjyang. Two separate bodies are also encountered at the confluence of the Masel Khola and the Daraundi Khola. The nepheline syenite bodies observed in the study area vary widely in their shape, size, and orientation. The largest pluton is observed in the vicinity of the villages Ampipal and Chanp Bhanjyang. It is about 7.5 km long in NNE-SSW direction and about 2 km wide. The second largest body is observed between the villages Bandre and Luintel Bhanjyang. It is about 2.5 km long approximately in east-west direction and 300 m wide. Numerous other smaller bodies ranging in size from hundreds of m to a few cm also occur in the region. The nephelinesyenites show sharp and irregular contacts with the country rock, they are crosscut by numerous dykes, and occasionally the effect of contact metamorphism is also observed in the country rock. The northeastern part of the largest nepheline syenite pluton (which occurs between Ampipal and Chanp Bhanjyang) is covered by about 500 m thick band of impure marbles. Rare, thin alternations of impure marble with phyllite as well as large (more than 10 m in diameter) scattered marble boulders areseen on the slopes NE of Chanp Bhanjyang, N of Bhulbhule Khar, at the saddle of Lagamkot, and at Khanigaun. The secondary mineralisation in the marbles is represented by magnetite, actinolite, biotite, and chlorite. There exist a few old iron mine workings in the magnetite mineralisation zones. Similar minerals are also seen in the nepheline syenite suggesting a direct relationship between the mineralisation in the nepheline syenite and the marbles. Generally, the nepheline syenite bodies exhibit the same trends of foliation and lineation as those of the country rock, and therefore, they must be intruded before the development of the secondary structures. There are a few hot springs at Bhulbhule Khar, which contain a high amount of H2S gas and sulphur, and are coming through the nepheline syenite. The development of copper as well as other secondary ore minerals and several generations of veins in the country rock, and the presence of hot springs probably indicate a continued hydrothermal activity in that area up to the recent times.

scholarly journals Sinistral transpression and hydrothermal activity during emplacement of the Early Proterozoic Julianehåb batholith, Ketilidian orogenic belt, South Greenland

1994 ◽  
Vol 163 ◽  
pp. 5-22
Author(s):  
B Chadwick ◽  
P Erfurt ◽  
T Frisch ◽  
R.A Frith ◽  
A.A Garde ◽  
...  
Keyword(s):  
Shear Zones ◽  
Field Work ◽  
Hydrothermal Activity ◽  
Vertical Shear ◽  
Early Proterozoic ◽  
North West ◽  
North East ◽  
The North ◽  
Granitoid Rocks ◽  
Quartz Veining

The first systematic investigations of the central part of the Early Proterozoic Ketilidian orogen in the vicinity of Søndre Sermilik in the early 1960s suggested that this part of the orogen comprised a mixture of the Julianehåb granite, altered supracrustal rocks and older orthogneisses. Recent field work has shown that the area consists only of a variably deformed suite of granitic to dioritic plutonic rocks and a range of hornblende-bearing dykes of the appinite suite which all belong to the Julianehåb batholith. Steep to vertical shear zones with widths from a few centimetres to more than one kilometre are a significant element of the structure. The principal shear zones trend north-east and they are parallel to the schistosity and subhorizontal linear structures in the granitoid rocks. Kinematic indicators in many of the shear zones indicate sinistral transcurrent displacements. The relationships between granite fabrics, shear zones and mafic dykes suggest that the Julianehåb batholith was emplaced during subduction from the south towards the Archaean craton in the north-west in a sinistral transpressional system. Effects of hydrothermal alteration, mainly in the form of quartz veining, silicification, chloritisation, epidotisation and pyritisation, are common within and adjacent to the largest shear zones. These effects are believed to be related to late stages of the evolution of the batholith. Gold anomalies appear to be closely tied to the hydrothermal phenomena.

Ras al Khaimah: further archaeological discoveries

Antiquity ◽  
1976 ◽  
Vol 50 (200) ◽  
pp. 216-222
Author(s):  
Beatrice De Cardi
Keyword(s):  
United Arab Emirates ◽  
The State ◽  
Focused Attention ◽  
North East ◽  
The North ◽  
History Of ◽  
The City

Ras a1 Khaimah is the most northerly of the seven states comprising the United Arab Emirates and its Ruler, H. H. Sheikh Saqr bin Mohammad al-Qasimi, is keenly interested in the history of the state and its people. Survey carried out there jointly with Dr D. B. Doe in 1968 had focused attention on the site of JuIfar which lies just north of the present town of Ras a1 Khaimah (de Cardi, 1971, 230-2). Julfar was in existence in Abbasid times and its importance as an entrep6t during the sixteenth and seventeenth centuries-the Portuguese Period-is reflected by the quantity and variety of imported wares to be found among the ruins of the city. Most of the sites discovered during the survey dated from that period but a group of cairns near Ghalilah and some long gabled graves in the Shimal area to the north-east of the date-groves behind Ras a1 Khaimah (map, FIG. I) clearly represented a more distant past.

Lichens in the North-East regions of Cyprus

1999 ◽  
Vol 110 (5-6) ◽  
pp. 455-463 ◽  
Author(s):  
S. Güvenç ◽  
Ş Öztürk
Keyword(s):  
North East ◽  
The North

TBE in Italy

2019 ◽  
Author(s):  
Valentina Tagliapietra ◽  
Flavia Riccardo ◽  
Giovanni Rezza
Keyword(s):  
Case Series ◽  
East Part ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low incidence country for tick-borne encephalitis (TBE) in Europe. Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.

TBE in Italy

2020 ◽  
Keyword(s):  
Surveillance System ◽  
Ad Hoc ◽  
National Level ◽  
Case Series ◽  
Incidence Rates ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low-incidence country for tick-borne encephalitis (TBE) in Europe.1 Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.2-5 A national enhanced surveillance system for TBE has been established since 2017.6 Before this, information on the occurrence of TBE cases at the national level in Italy was lacking. Both incidence rates and the geographical distribution of the disease were mostly inferred from endemic areas where surveillance was already in place, ad hoc studies and international literature.1

The influence of submesoscale eddies on hydrochemical parameters and structural and functional characteristics of phytoplankton in the north-eastern part of the Black Sea

2019 ◽  
pp. 24-40
Author(s):  
Sergey B. Kuklev ◽  
Vladimir A. Silkin ◽  
Valeriy K. Chasovnikov ◽  
Andrey G. Zatsepin ◽  
Larisa A. Pautova ◽  
...  
Keyword(s):  
Anticyclonic Eddy ◽  
The Black Sea ◽  
Hydrochemical Parameters ◽  
North East ◽  
The North ◽  
Seasonal Thermocline ◽  
North Eastern ◽  
Quantitative Indicators ◽  
The City ◽  
North Eastern Part

On June 7, 2018, a sub-mesoscale anticyclonic eddy induced by the wind (north-east) was registered on the shelf in the area of the city of Gelendzhik. With the help of field multidisciplinary expedition ship surveys, it was shown that this eddy exists in the layer above the seasonal thermocline. At the periphery of the eddy weak variability of hydrochemical parameters and quantitative indicators of phytoplankton were recorded. The result of the formation of such eddy structure was a shift in the structure of phytoplankton – the annual observed coccolithophores bloom was not registered.

Engineering-Geological Studies Of The Territory, Soils Of Foundation And Foundations Of The Architectural Monument Of The "Melnikov’s House" In Moscow

2019 ◽  
pp. 41-51
Keyword(s):  
Working Condition ◽  
Overlying Water ◽  
North East ◽  
The North ◽  
Geological Processes ◽  
Architectural Monument ◽  
Geological Conditions ◽  
Zone Of Influence ◽  
Complex Engineering ◽  
Building Engineering

On the basis of engineering and design surveys of the building, engineering-geological and geophysical studies of the soils of the territory conducted by the article authors, as well as with due regard for the results of studies conducted on this territory by other authors, the features of the foundations, soils of their foundation and engineering-geological conditions of the territory of the Melnikov House are established. It is shown that the Melnikov house is located under complex engineering-geological conditions on the territory of high geological risk, in the zone of influence of tectonic disturbance. To the North of the area there is a zone of intersection of the observed disturbance with a larger disturbance that can have an impact on geological processes. To the North-East of the site of the Melnikov House, a sharp immersion of the roof of carbon deposits was revealed. It promotes groundwater seepage into limestone of the carbonate strata from overlying water-bearing sands and activation of processes of suffusion removal and sinkhole phenomena of the soil. The surveyed area is assessed as potentially karst-hazardous and adjacent to it from the North-East territory as karst-dangerous. In this regard any construction on the adjacent territory can provoke activation of sinkhole phenomena on the surface. The foundations of the building are basically in working condition. Existing defects can be eliminated during repair. The foundation soils mainly have sufficient bearing capacity. Areas of the base with bulk soil can be reinforced. However, when developing a project for the reconstruction of the building and its territory, it should be taken into account that the design of the Melnikov House does not provide for its operation on the loads at the formation of sinkholes.

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