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Тhis paper represents palaeoenvironmental reconstructions for Lichvin interglacial and the transition to subsequent glaciation. Three warmings of interstadial rang have been established within this transitional period. The earliest Kosha interstadial was relatively warm. Subsequent Bulatovo and Mar`ino interstadials were distinct by more continental and colder climatic conditions.

The Ediacaran-Cambrian transition is marked by the diversification of metazoans in the marine realm. However, this is not recorded by the Ediacaran-Cambrian Bambuí Group of the São Francisco basin, Brazil. Containing the sedimentary record of a partially confined foreland basin system, the Bambuí strata bear rare metazoan remnants and a major carbon isotope positive excursion decoupled from the global record. This has been explained by changes in the paleogeography of the basin, which became a restricted epicontinental sea in the core of the Gondwana supercontinent, promoting episodes of shallow water anoxia. Here, we report new δ15Nbulk data from the two lowermost second-order transgressive-regressive sequences of the Bambuí Group. The results show a rise of δ15N values from +2 to +5‰ in the transgressive system tract of the basal sequence, which was deposited when the basin was connected to other marginal seas. Such excursion is interpreted as an oxygenation event in the Bambuí sea. Above, in the regressive systems tract, δ15N values vary from +2 to +5‰, pointing to instabilities in the N-cyle that are concomitant with the onset of basin restrictions, higher sedimentary supply/accommodation ratios, and the episodic anoxia. In the transgressive systems tract, the δ15N values stabilise at ∼+3.5‰, pointing to the establishment of an appreciable nitrate pool in shallow waters in spite of the basin full restriction as marked by the onset of a positive carbon isotope excursion. In sum, our data show that the N-cycle and its fluctuations were associated with variations in sedimentary supply/accommodation ratios induced by tectonically-related paleogeographic changes. The instability of the N-cycle and redox conditions plus the scarcity of nitrate along regression episodes might have hindered the development of early benthic metazoans within the Bambuí seawater and probably within other epicontinental seas during the late Ediacaran-Cambrian transition.

Parts of the Blue Nile basin showed good oil indications a decade ago, the puzzling question is why no oil draining. The common geological sense will go towards the lateral lithologic variations and its impacts on the porosity and permeability and thus towards the dynamics of the processes that governs and generate this architecture and the modes of its development. This study aims to reveal the basin architecture and its evolution, and it strongly suggests the application of constrained 2D backstripping technique using process oriented gravity modeling (POGM) technique and use the discrimination between the rift and sediment anomalies. By decompaction stratigraphic seismic sections, isostasy, recover the geometry of the crust at time of rift, calculating and adding the contribution of sediments and water to rift gravity anomaly, compare between the observed free air and the calculated gravity. POGM technique results a good discrimination between sediment and rift gravity contributions, and a value of 45 km thickness of elastic lithosphere, which is used to constrain the backstripping technique. Results from the backstripping shows the basin is a half graben type, the extension factor varies from 1.04 up to 1.1, which is accommodated by listric normal fault and the rotated blocks which compromise the hanging wall and developed to be the basin. The relative movement between these blocks and the foot wall goes different behaviors from acting independently to act as one unit this interplay change the normal faults into reverse faults, made temporal segmentation of the basin, relief, internal drainage patterns and migration of basin depocentre. From a tectonostratigraphic point of view, the Blue Nile basin evolution is given by different paleoenviroments and their positions in terms of time and space are controlled by interplay of sediment supply and basin capacity which are climatic and structural/thermal subsidence dependents respectively.

We present analytical results of organic compounds in the deep sea sediments recovered from the Central Pacific and the western tropical Pacific and describe recent progresses in sedimentary biomolecules as tools for reconstructing paleoenviroments. Biomolecules derived from terrestrial higher plants such as C25-C35 n-alkanes, C24-C28 fatty alcohols, or C23-C34 fatty acids in the surface sediments from 175° E transect show high concentrations in the higher latitudes in the Northern Hemisphere. Relative abundances of these terrestrial biomarkers are markedly different between low (15°N-15°S) and high (48°N-19°N) latitudes. Such a difference could be interpreted in terms of different wind regimes between the two areas. Unsaturation degree of long-chain alkenones (Uk37) derived from haptophyte algae suggests that sea surface temperature in the western tropical Pacific during the last glacial maximum was nearly the same as that of the present. We also found that the alkenone abundances over the last 20 kyr are anti-correlated with sedimentary nitrogen isotopic ratios, suggesting that a production rate of alkenones by haptophyte algae is controlled by the nutritional state of the algae.