Salinity reduction of the end-Triassic sea from the Alpine region into northwestern Europe

Abstract
The paleoecological analysis of the Penarth Group (= Rhaetic) of southern England and Wales [UK] is undertaken in terms of a species-richness comparison with the Zlambach and Koessen Beds of the Austrian Alps. The 3 groups studied, bivalves, foraminifers and ostracods, comprise the most important invertebrate faunas occurring in the deposits cited. All show significant diversity from the Alps into northwest Europe. Coupled with the disappearane of stenohaline elements including ammonites, and taking into account other facies information, the evidence suggests atransgression of a shallow epicontinental sea in northwest Europe at the end of the Triassic. The salinity of this sea (.apprx. 25-30.permill.) was appreciably below that of the Tethyan ocean.