The South Asian Monson (SAM) is one of the most intense climatic elements yet its initiation and variations are not well established. Dating the deposits of SAM wind-driven currents in IODP cores from the Maldives yields an age of 12. 9 Ma indicating an abrupt SAM onset, over a short period of 300 kyrs. This coincided with the Indian Ocean Oxygen Minimum Zone expansion as revealed by geochemical tracers and the onset of upwelling reflected by the sediment’s content of particulate organic matter. A weaker ‘proto-monsoon’ existed between 12.9 and 25 Ma, as mirrored by the sedimentary signature of dust influx. Abrupt SAM initiation favors a strong influence of climate in addition to the tectonic control, and we propose that the post Miocene Climate Optimum cooling, together with increased continentalization and establishment of the bipolar ocean circulation, i.e. the beginning of the modern world, shifted the monsoon over a threshold towards the modern system.

No abstract

Based on high-resolution reflection seismic and core data from IODP Expedition 359 we present a new channel-related drift type attached to a carbonate platform slope, which we termed delta drift. Like a river delta, it is comprised of several stacked lobes and connected to 3 3 a point source. The delta drifts were deposited at the exit of two gateways that connect the Inner Sea of the Maldives carbonate platform with the open ocean. The channels served as conduits focusing and accelerating the water flow; Entrained material was deposited at their mouth where the flows relaxed. The lobe-shaped calcareous sediment drifts must have formed under persistent water through flow. Sediment supply was relatively high and continuous, resulting in an average sedimentation rate of 17 cm ka-1. The two delta drifts occupy 342 and 384 km 2 , respectively; with a depositional relief of approximately 500 m. They have a sigmoidal clinoform reflection pattern with a particular convex upward bending of the foresets. In the Maldives the drift onset marks the transition from a sea-level controlled to a progressively current dominated depositional regime. This major event occurred in the Serravallian about 13 Ma ago, leading to the partial drowning of the carbonate platform and the creation of shallow seaways. The initial bank-enclosed topography resembles an "empty bucket" geometry which is rapidly filled by the drift sediments that aggrade and prograde into the basin. Thereby the depositional environment of the delta drifts changes from deep water (>500) to shallow-water conditions at their topsets, indicated by the overall coarsening upward trend in grain size and the presence of shallow water large benthic foraminifers at their top.

Please cite this article as: bertrand, L., geraud, Y., Le Garzic, E., Place, J., Diraison, M., Walter, B., Haffen, S., A multiscale analysis of a fracture pattern in granite: A case study of the Tamariu granite,The in-depth investigation of fractured reservoirs is mainly limited to geophysical data that 2 is in 3D and mostly on the scale of hundred meters to several kilometers or boreholes data that 3 is in 1D and at meter to lower scale. The study of outcropping analogs of buried reservoirs is 4 therefore a key tool for the characterization of the fault and fracture network at the reservoir 5 scale. Tamariu granite has been the subject of this study with the aim to analyze faults and 6 fractures from seismic to borehole scale. With the combination of satellite picture at different 7 resolution and field study, we perform a statistical analysis focused of the length and 8 orientation from infra centimeter crack to hundred kilometer length fault. On the whole range 9 of scale studied, i.e. on 7 orders of magnitude, we have defined a length distribution following 10 a power-law with an exponent a= -2. On the contrary to the length that can be modeled with a 11 unique law, the orientation data shows a variation depending on the scale of observation: as 12 the fault and fracture sets are suitable from the regional faults to the centimeter crack, the 13 proportion of the sets varies at each scale of observation.