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The Early Jurassic was characterized by extreme carbon-cycle perturbations that are associated with abrupt environmental and climatic change. However, the evidence mainly derives from sections in the western Tethys and northern Europe: localities situated in the northern hemisphere. This paper presents new records of foraminiferal biostratigraphic, sedimentological and carbonate carbon-isotope (δ 13 Ccarb) data from the Tibetan Kioto Platform formed in the southeastern Tethys (southern hemisphere) during the Sinemurian-lowermost Toarcian interval. Six foraminiferal zones have been recognized: late Sinemurian Textulariopsis sinemuriensis, Pliensbachian Planisepta compressa, Bosniella oenensis, Cyclorbitopsella tibetica and Streptocyclammina liasica, and earliest Toarcian Siphovalvulina sp. A. Based on biostratigraphy, δ 13 Ccarb data allow correlation with coeval records from the western Tethys and northern Europe by the identification of both negative and positive δ 13 C excursions. The negative excursions characterize the Sinemurian-Pliensbachian boundary event (SPBE) and the margaritatus-spinatum zone boundary event (MSBE); the positive δ 13 C excursion characterizes the margaritatus zone event (ME). Facies evolution in the Early Jurassic indicates that the establishment of carbonate sedimentation on the Kioto Platform occurred in the context of a global sea-level rise partly coincident with the SPBE and that, in common with other coeval platforms, carbonate production following the negative shift was predominantly made up of skeletal carbonates. Furthermore, the spread of the Lithiotis Fauna on the Kioto Platform followed the rebound of isotopic values after the SPBE. This phenomenon has been observed in the Western Tethys and suggests that the global biocalcification event represented by the flourishing of the Lithiotis Fauna may have occurred synchronously across the Tethys, possibly reflecting the creation of more favourable marine conditions after the SPBE. Biostratigraphic data indicate that certain index larger benthic foraminifera became extinct around the onset level of the MSBE, likely due to the deleterious impact of this event. However, as in 3 more northerly localities, the Lithiotis Fauna persisted during the late Pliensbachian in the shallow-water platforms of the Tethys until its disappearance in the early Toarcian.

Early Jurassic syn-sedimentary extensional tectonics in the central Southern Alps controlled patterns of deposition within\ud the Calcari Grigi carbonate platform. We used variogram maps to gather model-independent information on the spatial distribution of thicknesses of selected platform units and investigated whether major syn-sedimentary faults outlined subsiding domains during platform growth. Thicknesses display a spatial organization that suggests that large fault belts, often coincident with exposed Jurassic extensional structures, transected large parts of the platform. The network of four fault systems (trending NNW–SSE and NE–SW) displays orthorhombic symmetry, suggesting non-Andersonian faulting and a true triaxial strain field with N100°E maximum extension or transfer shear zones connecting major NNW–SSE trending extensional faults. In both cases, inherited structures of Permian to Triassic age may have played a primary role in Jurassic faulting. If confirmed throughout the South-Alpine domain, this arrangement could shed new light on Early Jurassic rifting mechanisms in the Southern Alps

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