The Romanche transverse ridge (equatorial Atlantic) is located in the northern flank of the fracture zone, opposite the eastern ridge-transform intersection (RTI). It constitutes a major positive topographic anomaly that reaches a height of over 4 km above the level predicted by the thermal subsidence curve. A series of E-W aligned peaks, located on the crest of the transverse ridge, were at sea level during early and middle Miocene times; they are presently capped by a ~300 m thick, shallow-water carbonate platform that grew on a subsiding oceanic crust basement surface flattened by erosion at sea level. These structures are now about 1 km below sea level. High resolution seismic reflection surveys and multibeam morphobathymetry as well as study of samples recovered from the carbonate platform allowed a reconstruction of the paleoenvironment and of the vertical movements of the peaks starting from the lower Miocene. Ages derived from microfossils suggest that the base of the carbonate platform dates from 17-25 m.y. ago and the sinking of the platform started between 18 and 13 m.y. ago. These data were included in a numerical simulation model that takes into account thermal and tectonic subsidence, growth potential of the carbonates, subaerial and submarine erosion rates and Mio-Pliocene absolute sea level fluctuations. The results outline the subsidence history of the Romanche transverse ridge and suggest post-Miocene subsidence faster than that predicted by the thermal cooling model.

Der zuerst (1851) erwähnte Horizont ist derjenige der Macrocephalus-Schichten in der Umgebung von Wölflinswil . Er wurde dort ins Oxfordien gestellt, dessen Basis durch einen  rugensteinförmigen Thoneisen-stein» gebildet wird, eine Schicht, die sich wohl am ehesten mit dem englischen Kelloway Rock vergleichen lässt. <...>

The present study is a report on the volcanic deposits which form the southern part of the Absaroka Range and which occur in the adjoining region in northwestern T/yoraing* This investigation has been undertaken with the object of eliminating discrepancies in correlation within the lower subdivisions of the Absaroka Range, chiefly between the Bighorn and Wind River basins.

Stream sediment geochemistry has been described as a very robust, successful mineral exploration technique and has proven to be effective even when sampling was poorly carried out (Fletcher, 1997). Much of its early success for discovering new mineral deposits in British Columbia can be traced to the pioneers of exploration geochemistry who recognized the ability of more mobile elements such as copper and zinc to concentrate in sediment from broad range of stream environments. This proved to be an advantage in the 1950’s when exploration focused primarily on the search for porphyry copper deposits. Sediment sampling techniques could afford to be less rigorous because formation of copper stream geochemical anomalies was less susceptible to the variations in sample site environment. However, it became apparent that geochemical surveys for gold and other heavy minerals needed more careful collection of sediment from a specific energy environment so that maximum anomaly contrast could be achieved. <...>