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[en] On the southern side of the Beausset syncline (southwest Provence), lithostratigraphic and structural propositions are divergent. Since 1978, the available geological map at 1/50 000 has revealed these contradictions. During the recent revision of these maps at 1/10 000 scale and with detailed triasic lithostratigraphy, the authors have proposed a new interpretation of the relationship between the Trias and Santonian in diverse structural units of this area. These facts confirm premature tectonic phases (before Santonian), evoked since 1891 by M. Bertrand in this area (Saint-Jean oratory), where the embryonic structures are taken back in the following phases of the Paleogene. Similarly to the other hills around Toulon (Var), this premature genesis of the provençal folds can be attributed to the diapiric behaviour of the Trias, which seems to be the main engine of these local and initial structures. (Author)
[en] Full text : The plegicil-geographical researches had established the predominant development of definite non-anticlinal traps in some stages and oil deposits related with them. At the final stage of the Alpine tectonic cycle more favorable conditions rise for formation of paleogemorphological and structural-stractigraphical types of non-anticlinal traps due to relation with increase of the tectonic movements contrast and existence of numerous regional and local bakers in sedimentation. The complex history of the geotechnical development of the mentioned large tectonic units made the favorable conditions for formation of non-anticlinal traps of different in various stratigraphical complexes. Marine tangerines begun in the Early Cretaceous had led to accumulation of carbonaceous mainly, then sandy-clayey formations. The Middle Cretaceous is characterized with instability of the geotectonic regime
[en] Complete text of publication follows. The relationship between the strength and stability of the Earth's magnetic field and its tendency to reverse is a matter of continuing debate. A key time period in which to investigate the link is the Cretaceous Normal Superchron (CNS) when the field remained in a normal polarity for 40 Ma. Considerable effort to produce high quality palaeointensity estimates from the CNS is underway however this is no easy task. Finding suitably aged (and dated) material from which reliable palaeodirections can be obtained is just the start. Here we assess the presently available data in the global database and discuss recent results obtained using the microwave palaeointensity technique. The advantage of using the microwave method compared to the conventional Thellier method is that alteration during the experiment can be reduced leading to higher experimental success rates. However, as with the conventional Thellier method, samples must contain an original thermal remanence carried by single domain behaving grains. Detailed rock magnetic and microscopy studies in conjunction with comparisons to results from other studies at the sample, flow and site level are used to investigate possible biases.
[en] Based on the background of Yanshanian tectonic activity in the northern Junggar basin, the temporal and spatial distribution characteristics of Yanshanian unconformity events in the northern Junggar basin are systematically studied through interpretation and comparison of outcrop profiles and seismic profiles. The study shows that Yanshanian stratigraphic unconformity in the northern part of Junggar Basin mainly manifests in the angle unconformity between Xishanyao formation and Toutunhe formation, Toutunhe formation and Tugulu group, which indicates that the study area mainly experienced three important periods of unconformity: the end of Xishanyao formation in middle Jurassic, the end of Toutunhe formation and the end of Tugulu group in early Cretaceous. From the analysis of the unconformity structure and its regional distribution characteristics, it can be concluded that the most prominent Yanshanian tectonic unconformity events occurred mainly in the late Jurassic and showed the unconformity distribution characteristics of the weak compression fold deformation under the background of strike-slip uplift. (paper)
[en] Data on the N and C isotopic composition are presented for the Lower Triassic claystones of the Abrek section of southern Primorye (Far East). The results showed five N isotopic intervals and several negative C isotopic excursions of the Induan–lower Olenekian stages of the Abrek section.
[en] The geologic and metallogenic characteristic of the metamorphic Massif shows the presence of possible uranium vein type mineralization as a result of a hidrotermal genetic process. Metalliferous fluids rising along the fault system were responsible for the deposition of the uranium in the reduction zones, i.e. presence of pyrite, organic matter and others. This type of uranium minerization is proposed for the Bibijagua area and for the Revolucion and Lela area the same type is expected. The gamma spectrometric analysis was used to evaluate the geological samples
[en] The plate tectonics theory generally leads us to consider that Iberia was an independent plate separated from Europe by the North Pyrenean Fault (NPF). The NPF has been commonly interpreted as a transform fault associated with a huge counterclockwise transverse and rotational movement that allowed the opening of the Bay of Biscay and the relative eastward motion of Iberia during the Mesozoic. According to some interpretations, this movement may have generated an interplate gap several hundreds of km wide, which led to the creation of an oceanic crust during the Late Jurassic and Early Cretaceous. However, field studies recently carried out in the Pyrenees do not support these interpretations. The North Pyrenean Fault (NPF) of Tertiary age is observed in the central and eastern Pyrenees, where pioneering researchers defined it as separating the North Pyrenean Zone from the Axial Zone.However, this fault cannot be identified in the western part of the range to the west of the Ossau valley. Consequently, the geodynamic evolution of Iberia has always been dependent on Europe, especially during the failed oceanic rifting in the Mid-Cretaceous. Indeed, during this period, a central zone of crustal thinning occupied by turbiditic basins separated the European from the Iberian continental crust, with a very localized mantle exhumation found only in the Mauleon basin. Therefore, far from being an interplate range, the Pyrenees can neither be considered as an intraplate unit. We can define this orogenic belt as resulting from the Tertiary tectonic inversion of a Mid-Cretaceous rift system. According to this new interpretation, Iberia would not have been an isolated plate but represented an unstable, outlying part of Europe. Rather than displaying the features of a rigid lithospheric unit with well-defined boundaries, Iberia grouped together different crustal blocks undergoing specific movements at particular times. During the Mesozoic, normal, reverse or strike-slip displacements along their boundary faults generated several en echelon basins (Bilbao, Logrono, Soria and Maestrazgo in Spain; Parentis, Arzacq and the North Pyrenean Flysch Trough in France) whose diachronous development accounts very well for the opening of the Bay of Biscay and the relative W-E sinistral movement of the Iberian crust with respect to the European crust. In this way, we note a more marked paleogeographic shift in the western Basque region than in eastern Catalonia. Therefore, the Pyrenees were not generated by an interplate collision, but merely reflect the confrontation of two distended but continuous continental domains during the Tertiary, leading to the incipient underthrusting of the Iberian crust under the European crust. This zone of confrontation/convergence does not correspond in any way to the NPF, but rather comprises a complex imbricated structure revealed by a jump in the Moho, both in the Pyrenees and in the Cantabrian belt, which has recently become known as the North Iberian Fault. (Author)
[en] Three exploration wells were selected near Mosul city (Az-29, Bm-15, and Kd-1) to study the palynozones and hydrocarbon generation potential of the Upper Triassic Baluti and Kurrachine Formations. This study was completed in two phases: The first was a study of palynofacies and their paleoenvironmental indications, degree of preservation, diversity of palynomorphs, and organic maturity of the rocks according to palynomorphs' color using a refracted light microscope. More than 80 slides of organic matter were used for this study. Four palynofacies were tentatively recognized. (1) The first palynofacies is diagnostic of the Baluti Formation in the Az-29 and Kd-1 wells; (2) The second palynofacies appeared at different depths in the Kurrachine Formation in three wells. (3) The third was only found between the depths of 4,534 to 4,685 m in the well Az-29. (4) The fourth was only found between 3,500- and 3590-m depth in the well Bm-15. A distal coastal marine environment is suggested for the Baluti Formation and restricted lagoonal environment for the Kurrachine Formation. The second phase used organic geochemical analyses to confirm the suggested paleoenvironmental and hydrocarbon generation material. Three techniques were used, namely total organic carbon, pyrolysis, and pyrolysis gas chromatography, on more than 35 samples from different depths in three wells. The analyses proved that a sufficient quantity of organic matter occurs that and has suitable maturity for hydrocarbon generation potential of oil and gas. (author)
[en] In Liard Basin of northern British Columbia, syn-depositional motion on the Bovie structure resulted in greater thicknesses of Cretaceous sediments. The Early Cretaceous Garbutt Formation was deposited during the initiation of a major marine transgression. Organic-rich shales and siltstones in its lower part record maximum flooding and have been informally termed the Radioactive Zone (RZ). The Garbutt Formation is dominated by shales and siltstones and is here subdivided into three informal units; the lower Garbutt Formation (LGF), the succeeding RZ and the upper Garbutt Formation (UGF). The combined thickness of the Radioactive Zone and lower Garbutt Formation is 40 to over 120 m thick and can be at greater than 2000 m depth in Liard Basin. The lower Garbutt Formation is not recognized east of the Bovie structure and the RZ is considerably thinner or absent locally, suggesting this area remained high relative to Liard Basin. Total organic carbon and Rock-Eval data suggest that the RZ is a good to very good source rock and that the LGF is also a good source rock. Organic matter is dominantly Type II kerogen, although more terrestrial Type III input becomes prevalent in western parts of the basin. Thermal maturity inferred from Tmax, in addition to hydrogen index levels, indicate that these rocks are in the oil window in northern Liard Basin and in the wet gas window within central Liard Basin. Porosities average 8% and matrix compositions average 39 wt.% quartz, 4 wt.% feldspar and calcite and 53 wt.% clays (illite/mica, kaolinite and chlorite). The properties of the RZ and LGF indicate that a potential liquids-rich shale gas play may occur within central Liard Basin. (author)