Geology

Biography

Biography: Frank Mattern

Abstract

To distinguish different SRSF environments, detailed measured sections, their comparison and correlation are essential. Unchannelized outer fan deposits display simple, parallel bedding of high lateral continuity. Mid-fan channels exhibit complex bedding patterns with vertical and lateral random distributions of channel fills, axial erosion, bed convergence towards the channel margins and linear bed continuity. Only outer fan beds can be laterally correlated on a local to regional scale. Inner fans/fan valleys are rarely exposed. Fan environments can further be distinguished by (1) different turbidite facies associations: mainly B, C and D in outer and A, B, C, D, and channel margin facies in middle fans, (2) greater average bed and layer thicknesses in mid-fans than in outer fans, (3) more frequent amalgamations in channel fills than in outer fans, (4) more frequent tabular amalgamations in outer fans, (5) more frequent nontabular amalgamations in mid-fan channels, and (6) more frequent dish structures in mid-fan channels. Fan valley fills comprise coarse conglomerates. In their vicinity mud-rich basin slope deposits may occur. SRSFs occur in restricted continental basins, either isolated or as coalescing fans. Lateral fan extent often measures close to 25 km with thicknesses usually Ë‚300 m. Their shape in plain view (radial, curved) depends on the basin floor slope. SRSF formation is closely related to tectonics. Their sand is immature, deriving from nearby sources and transported by short rivers with a steep gradient. Tectonics provide for narrow shelves, making SRSFs relatively insensitive to sea-level changes. Submarine canyons may intercept sand from longshore drift and/or rivers and funnel it to the fans.