Structure and stratigraphy of the Borrowdale Volcanic rocks of the Kentmere area, English Lake District

Abstract

The Borrowdale Volcanic rocks of Kentmere have been reinvestigated. A previous structural interpretation (Mitchell 1929) involving Caledonian isoclines superimposed upon pre-Caradocian NNE trending folds is shown to be incorrect; neither set of structures exist. The geometry of the major structural elements in the area, the Nan Bield Anticline and the Caledonoid cleavage, is described. Evidence is adduced which suggests that the anticline was formed in pre-Caradxian time as a large open fold trending approximately E-W. Its present geometry and that of the Wren Gill Monocline result from the superimposition of the regional end-Silurian cleavage obliquely and inhomogeneously across this preexisting fold.The volcanic succession is divided into four compositionally and petrographically defined formations. In upward sequence these are the Nan Bield and Wren Gill formations (andesitic lavas and tuffs), Kentmere Formation (mainly dacitic pryoclastic rocks) and the Garbourn Formation (andesites and dacites), totalling over 2800 m. It is thought that much of this succession was deposited subaqueously.

Initial Time Of Two High Altitude Crater Lakes (Nevado De Toluca, Central Mexico) Recorded In Subfossil Cladocera

“…Lakes are fre quently the ob jects of both lim no logi cal and palaeolimnological stud ies. Their gen e sis and ages are a subject of in ter est for many re search ers around the world (McNamara, 1979;Soper, N.J. and Numan, N.M.S., 1974;Wiêckowski, 2009). The ma jor ity of stud ies fo cused on high lat i tude and low land lakes.…”