ALBERT

Description: Three fundamental stages of the Cretaceous-Neogene tectonic evolution of the Odessa Shelf and Azov Sea (northern margins of western and eastern Black Sea basins, respectively) have been documented from the analysis of reinterpreted regional seismic profiling and one-dimensional (1-D) subsidence analysis of 49 wells, for which the stratigraphic interpretation was recently revised. (1) An initial active rifting stage began within the Early Cretaceous (not later than Aptian-Albian times) and continued until the end of the Santonian in the Late Cretaceous (c. 128-83 Ma). A system of half-grabens with mainly south-dipping normal faults developed on the Odessa Shelf at this time. The most profound faulting, accompanied by volcanic activity, occurred in the NE-SW orientated Karkinit-Gubkin rift basin at the boundary between the Eastern European and Scythian platforms. The footwalls of half-grabens were exposed above sea level and subject to erosion at this time. Active extensional processes affected the western part of Azov Sea and, while the onset and cessation of these cannot be tightly constrained, they are compatible with the well constrained results from the Odessa Shelf. (2) The second tectonic stage is one of passive post-rift thermal subsidence that lasted from the Campanian (Late Cretaceous) until the end of the Middle Eocene (83-38.6 Ma). (3) The third stage of basin evolution is one of inversion tectonics in a compressional setting. Discrete inversion events occurred at the end of the Middle Eocene, during the Late Eocene, during the Early Miocene and at Middle Miocene times (c. 38.6 Ma, c. 35.4 Ma, c. 16.3 Ma, c. 10.4 Ma, respectively) and typical inversion structures developed on the Odessa Shelf, some parts of which were uplifted and significantly eroded (down to the Lower Cretaceous succession). The southern part of the Azov Sea, opening into the northernmost eastern Black Sea basin, subsided rapidly during this time; thereafter, until the Quaternary, rapid subsidence was limited to its southeastern part, which was incorporated into the Indolo-Kuban foreland basin of the Greater Caucasus orogen.

Description: Fishers' knowledge research (FKR) aims to enhance the use of experiential knowledge of fish harvesters in fisheries research, assessment, and management. Fishery participants are able to provide unique knowledge, and that knowledge forms an important part of "best available information" for fisheries science and management. Fishers' knowledge includes, but is much greater than, basic biological fishery information. It includes ecological, economic, social, and institutional knowledge, as well as experience and critical analysis of experiential knowledge. We suggest that FKR, which may in the past have been defined quite narrowly, be defined more broadly to include both fishery observations and fishers "experiential knowledge" provided across a spectrum of arrangements of fisher participation. FKR is part of the new and different information required in evolving "ecosystem-based" and "integrated" management approaches. FKR is a necessary element in the integration of ecological, economic, social, and institutional considerations of future management. Fishers' knowledge may be added to traditional assessment with appropriate analysis and explicit recognition of the intended use of the information, but fishers' knowledge is best implemented in a participatory process designed to receive and use it. Co-generation of knowledge in appropriately designed processes facilitates development and use of fishers' knowledge and facilitates the participation of fishers in assessment and management, and is suggested as best practice in improved fisheries governance.

Description: Ellesmere Island in Arctic Canada displays a complex geological evolution. The region was affected by two distinct orogenies, the Palaeozoic Ellesmerian orogeny (the Caledonian equivalent in Arctic Canada and Northern Greenland) and the Palaeogene Eurekan orogeny, related to the opening of Baffin Bay and the consequent convergence of the Greenland plate. The details of this complex evolution and the present-day deep structure are poorly constrained in this remote area and deep geophysical data are sparse. Receiver function analysis of seven temporary broad-band seismometers of the Ellesmere Island Lithosphere Experiment complemented by two permanent stations provides important data on the crustal velocity structure of Ellesmere Island. The crustal expression of the northernmost tectonic block of Ellesmere Island (~82°–83°N), Pearya, which was accreted during the Ellesmerian orogeny, is similar to that at the southernmost part, which is part of the Precambrian Laurentian (North America-Greenland) craton. Both segments have thick crystalline crust (~35–36 km) and comparable velocity–depth profiles. In contrast, crustal thickness in central Ellesmere Island decreases from ~24–30 km in the Eurekan fold and thrust belt (~79.7°–80.6°N) to ~16–20 km in the Hazen Stable Block (HSB; ~80.6°–81.4°N) and is covered by a thick succession of metasediments. A deep crustal root (~48 km) at ~79.6°N is interpreted as cratonic crust flexed beneath the Eurekan fold and thrust belt. The Carboniferous to Palaeogene sedimentary succession of the Sverdrup Basin is inferred to be up to 1–4 km thick, comparable to geologically-based estimates, near the western margin of the HSB.

Description: The Greater Caucasus and southern Crimean Mountains form part of a fold–thrust belt located on the northern margin of the Black Sea, south of the Precambrian craton of eastern Europe. Its southern limit is approximated by the Main Caucasus Thrust, which runs to the west from onshore Russia and Georgia along the whole of the northern margin of the Black Sea. The Main Caucasus Thrust is related to a zone of present-day seismicity along the southern Crimea–Caucasus coast of the Black Sea called the Crimea–Caucasus Seismic Zone. Thick continental crust north of the Main Caucasus Thrust lies adjacent to the thin ‘suboceanic' or transitional crust of the Black Sea Basin. A local seismic tomography study of this area in the vicinity of the Kerch and Taman peninsulas, which lie between the Azov Sea and the Black Sea, has been carried out based on 195 weak (m b ≤3) earthquakes occurring from 1975 to 2010 and recorded at four permanent and three temporary seismological stations on the Kerch and Taman peninsulas. The results, for a volume of about 200 x 100 km (east–west and north–south, respectively) and a depth of about 40 km, provide evidence for significant heterogeneity in the P-wave and S-wave velocities. Velocities inferred in the northern part of the model suggest that the continental crust underlying the Crimea–Azov region north of the Main Caucasus Thrust is of different tectonic affinity (cratonic) than that underlying the northeastern part of the Black Sea, south of the Main Caucasus Thrust (Neoproterozoic–Palaeozoic accretionary domain). In the southern part of the model, at depths of 25–40 km, the uppermost mantle below the thin quasi-oceanic crust of the Black Sea has anomalous low P-wave velocities with high P- to S-wave velocity ratios. This is tentatively interpreted as representing serpentinized upper mantle of continental lithosphere exhumed during Cretaceous rifting and lithospheric hyperextension of the eastern Black Sea. The transition between the continental domains and the crust underlain by anomalous upper mantle is closely related to the Crimea–Caucasus Seismic Zone, where earthquake foci deepen northwards, suggesting that the latter is being thrust under the former in this intra-plate setting.

Description: The DOBRE-2 wide-angle reflection and refraction profile was acquired in June 2007 as a direct, southwestwards prolongation of the 1999 DOBREfraction'99 that crossed the Donbas Foldbelt in eastern Ukraine. It crosses the Azov Massif of the East European Craton, the Azov Sea, the Kerch Peninsula (the easternmost part of Crimea) and the northern East Black Sea Basin, thus traversing the entire Crimea–Caucasus compressional zone centred on the Kerch Peninsula. The DOBRE-2 profile recorded a mix of onshore explosive sources as well as airguns at sea. A variety of single-component recorders were used on land and ocean bottom instruments were deployed offshore and recovered by ship. The DOBRE-2 datasets were degraded by a lack of shot-point reversal at the southwestern terminus and by some poor signal registration elsewhere, in particular in the Black Sea. Nevertheless, they allowed a robust velocity model of the upper crust to be constructed along the entire profile as well as through the entire crust beneath the Azov Massif. A less well constrained model was constructed for much of the crust beneath the Azov Sea and the Kerch Peninsula. The results showed that there is a significant change in the upper crustal lithology in the northern Azov Sea, expressed in the near surface as the Main Azov Fault; this boundary can be taken as the boundary between the East European Craton and the Scythian Platform. The upper crustal rocks of the Scythian Platform in this area probably consist of metasedimentary rocks. A narrow unit as shallow as about 5 km and characterized by velocities typical of the crystalline basement bounds the metasedimentary succession on its southern margin and also marks the northern margin of the northern foredeep and the underlying successions of the Crimea–Caucasus compressional zone in the southern part of the Azov Sea. A broader and somewhat deeper basement unit (about 11 km) with an antiformal shape lies beneath the northern East Black Sea Basin and forms the southern margin of the Crimea–Caucasus compressional zone. The depth of the underlying Moho discontinuity increases from 40 km beneath the Azov Massif to 47 km beneath the Crimea–Caucasus compressional zone.

Description: The origin and age of topography along the west Greenland margin is a matter of continued debate. Evidence for tectonically driven Neogene uplift has been argued from interpretations of offshore seismic surveys, onshore fission-track data and inferred episodes of cooling. Here, analysis of seismic reflection profiles and 1D modelling of exploration wells along the Greenland margin of Davis Strait demonstrate that the data are consistent with a model of ancient continental topography affected by late Cretaceous–early Palaeocene rifting followed by thermal subsidence where offshore Neogene tectonic uplift is not required. This interpretation for the offshore evolution of the west Greenland margin has implications for the adjacent onshore evolution and for other continental margins developed throughout the Atlantic–Arctic rift system.

Description: 〈span〉〈div〉SUMMARY〈/div〉Recently an ambitious experiment combining deep seismic surveys from near-vertical and wide-angle acquisition methods was carried out in Brazil. The seismic lines are essentially coincident and crossed the Parnaíba Basin from west to east near latitude 5°S. Here, the wide-angle reflection and refraction (WARR) and deep seismic reflection (DSR) results, which were previously interpreted independently, are compared by directly correlating WARR interfaces converted to TWTT with the major reflective horizons identified in the zero-offset image and by considering coincident reflectivity patterns displayed in both data sets. This integrated WARR and DSR analysis allowed a spatial association of the apparently acoustically featureless crust imaged in the DSR profile to the high reflectivity observed in the WARR data. Numerical tests and elastic modelling show that variations of the elastic properties of the crust, particularly as they are characterized by low 〈span〉Vp〈/span〉 and 〈span〉Vs〈/span〉 contrasts with a possible increase of the 〈span〉Vp〈/span〉/〈span〉Vs〈/span〉 ratio, can only weakly explain the observed reflectivity patterns but that fine-scale lithological heterogeneity within the crust is capable of replicating the observed contrasting seismic responses. The segment of the Parnaíba Basin crust that is characterized by fine-scale lithological heterogeneity lies directly above a mafic crustal underplate defined by the WARR model and was named as the Grajaú domain on the basis of WARR-derived velocity model. The applied methodologies allow added value to be taken from the independent seismic data sets and provide new information about crustal structure that may have important implications for overlying intracontinental basin evolution.〈/span〉

Description: The sedimentary basins of the Davis Strait area developed mainly as a result of late Mesozoic and Cenozoic rifting processes that led to the formation of the West Greenland, southeast Baffin, and east Labrador continental margins. Recently acquired regional geophysical data in the area provide considerable new constraints on sedimentary basin and crustal thicknesses as well as plate kinematic reconstructions. Further, the chrono-stratigraphy and vitrinite reflectance data for several of the northern Labrador margin wells have been re-correlated and corrected. Given this, new 1-D models for the subsidence and thermal evolution of a number of the exploration wells located on the conjugate West Greenland and east Baffin/Labrador margins have been computed. Model predictions based on lithospheric extension agree well with observed stratigraphic and thermal data from West Greenland, southeast Baffin, and east Labrador wells. Calculated stretching factors for the wells are remarkably similar, except for those off southeast Baffin Island, which are higher. This implies that this area was subject to more intense rifting prior to the onset of magmatism in the early Paleocene. In turn, this may suggest that the magmatism was related to rifting and not, as commonly believed, linked to the arrival of a mantle plume at the beginning of the Paleocene. The modelled thermal histories indicate that maximum subsurface temperatures occurred at different times throughout the Cenozoic, depending mainly on the sedimentation (burial) histories, surface temperatures, and heat flow. Prediction of hydrocarbon generation in the area must therefore include these parameters.