Beschreibung: Mayotte fore-slopes exhibit a distinct pattern in overall morphology, starting in the deep with an unlithified sedimentary wedge and slope, followed upwards by a cemented slope, and finally by a steep, almost vertical wall. On top of the wall, drowned reefs occur. Dated corals may reveal the history of sea-level changes indicating pristine reef growth during late isotope stage 3 (at 55–24 ka) at a present-day water depth greater than 80 m. A maximum sea-level drop of 150 m occurred during the last glacial maximum, around 20 ka. This lowering of sea-level is documented by karst features such as small caves and corroded and jagged surfaces. The phase of deglaciation is recorded by two give-up reef levels at 100–90-m water depth and 65–55-m water depth which we may relate to the Bølling (14 ka) and post Younger Dryas (11.5 ka) meltwater pulses, known from the deep-sea record.

Beschreibung: Mayotte fore-slopes exhibit a distinct pattern in overall morphology, starting in the deep with an unlithified sedimentary wedge and slope, followed upwards by a cemented slope, and finally by a steep, almost vertical wall. On top of the wall, drowned reefs occur. Dated corals may reveal the history of sea-level changes indicating pristine reef growth during late isotope stage 3 (at 55–24 ka) at a present-day water depth greater than 80 m. A maximum sea-level drop of 150 m occurred during the last glacial maximum, around 20 ka. This lowering of sea-level is documented by karst features such as small caves and corroded and jagged surfaces. The phase of deglaciation is recorded by two give-up reef levels at 100–90-m water depth and 65–55-m water depth which we may relate to the Bølling (14 ka) and post Younger Dryas (11.5 ka) meltwater pulses, known from the deep-sea record.

Beschreibung: The plateau of Jbel Bou Dahar (High Atlas, Morocco) represents an outstanding example of a well-preserved early Mesozoic carbonate platform. Field observations of the large-scale sedimentary structures and the arrangement of lithofacies associations within the mid- and lower slope were combined with detailed microfacies analyses and gamma-ray measurements. The investigations were carried out in order to (1) resolve the sequence stratigraphic architecture of the slope, and (2) reconstruct the sediment export patterns and depositional processes related to high-frequency sea-level variations. The slope strata are arranged into two different types of lithofacies associations that are bounded by characteristic discontinuities and show a specific occurrence along the investigated slope section. The steep (8-18°) mid-slope is dominated by thick- to medium-bedded limestone successions that were able to maintain a high angle of repose due to their detrital composition. The sediment packages are bounded by basal low-angle unconformities and wedge out within the lower slope or thin into the adjacent basin as single carbonate layers. The sediments are characterized by coarse-grained and poorly sorted floatstones to rudstones, which show low gamma-ray values and contain components derived mainly from the platform edge. The facies associations were interpreted as debris-flow deposits that were exported during sea-level lowstands when the flattened platform top and extended parts of the margin were exposed and sediment production was restricted mainly to the outer margin and upper slope section. In contrast, the gently dipping lower slope (4-18°) is characterized by rhythmic limestone-marl alternations that show increasing thicknesses with increasing distance from the platform. From the lower part of the mid-slope down, the successions onlap the debris-flow deposits, forming a characteristic interfingering pattern of different lithofacies associations. The medium- to thin-bedded carbonates of the limestone-marl alternations comprise two different microfacies types: (1) mudstones to wackestones with high gamma-ray values and a mixed shallow-marine to deep-marine microfacies, overlain by (2) well-sorted, arenitic packstones to grainstones with low gamma-ray values and a shallow-marine component composition. The latter points to the platform interior and margin as primary source areas. The shallow-marine material was exported during sea-level highstands when the carbonate factory included the entire platform margin and the flooded lagoons of the platform top. During these periods, the exported fine-grained sediments could maintain only low angles of repose. Thus they bypassed the steep upper and mid-slope sections, developed into turbidites during downslope transport, and were finally redeposited on the gently dipping lower slope and in the adjacent basin. The architecture of the investigated slope area shows a characteristic interfingering of different facies associations that can be interpreted as genetic highstand and lowstand stratigraphic sequences. The arrangement of these sequences along the slope, as well as their composition, were controlled by high-frequency sea-level fluctuations, affecting the primary sediment production (source area), export patterns, and sedimentary processes, resulting in a shift of the depositional centers during different sea-level stands.

Beschreibung: Stratigraphic records from northwestern Pangea provide unique insight into global processes that occurred during the latest Permian extinction (LPE). We examined a detailed geochemical record of the Festningen section, Spitsbergen. A stepwise extinction is noted as: starting with (1) loss of carbonate shelly macrofauna, followed by (2) loss of siliceous sponges in conjunction with an abrupt change in ichnofabrics as well as dramatic change in the terrestrial environment, and (3) final loss of all trace fossils. We interpret loss of carbonate producers as related to shoaling of the lysocline in higher latitudes, in relationship to building atmospheric CO 2 . The loss of siliceous sponges is coincident with the global LPE event and is related to onset of high loading rates of toxic metals (Hg, As, Co) that we suggest are derived from Siberian Trap eruptions. The final extinction stage is coincident with redox-sensitive trace metal and other proxy data that suggest onset of anoxia after the other extinction events. These results show a remarkable record of progressive environmental deterioration in northwestern Pangea during the extinction crises.

Beschreibung: The controversial Capitanian (Middle Permian, 262 Ma) extinction event is only known from equatorial latitudes, and consequently its global extent is poorly resolved. We demonstrate that there were two, severe extinctions amongst brachiopods in northern Boreal latitudes (Spitsbergen) in the Middle to Late Permian, separated by a recovery phase. New age dating of the Spitsbergen strata (belonging to the Kapp Starostin Formation), using strontium isotopes and d 13 C trends and comparison with better-dated sections in Greenland, suggests that the first crisis occurred in the Capitanian. This age assignment indicates that this Middle Permian extinction is manifested at higher latitudes. Redox proxies (pyrite framboids and trace metals) show that the Boreal crisis coincided with an intensification of oxygen depletion, implicating anoxia in the extinction scenario. The widespread and near-total loss of carbonates across the Boreal Realm also suggests a role for acidification in the crisis. The recovery interval saw the appearance of new brachiopod and bivalve taxa alongside survivors, and an increased mollusk dominance, resulting in an assemblage reminiscent of younger Mesozoic assemblages. The subsequent end-Permian mass extinction terminated this Late Permian radiation.