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Palaeomagnetism and chronology of Caledonian igneous episodes in the Cross Fell Inlier and northern Lake District
Author(s) -
Piper J. D. A.,
Mccook A. S.,
Watkins K. P.,
Brown G. C.,
Morris W. A.
Publication year - 1978
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350130108
Subject(s) - fell , geology , paleomagnetism , paleozoic , chronology , orogeny , volcano , dike , paleontology , igneous rock , group (periodic table) , ordovician , volcanic rock , geochemistry , tectonics , chemistry , organic chemistry
This study employs palaeomagnetism to differentiate between Palaeozoic minor intrusions in northern England. The lamprophyres of the Cross Fell Inlier subdivide petrographically into kersantites and minettes. All the kersantites have steep directions of magnetisation probably correlating with an interval of anomalous geomagnetic field in Caradocian times. The Threlkeld–St John's microgranodiorite (445 m.y.) and Carrock Fell dolerite dyke swarm also possess steep magnetisations assigned to the same interval. The minettes have shallow directions of magnetisation similar to the Shap Granite (393 m.y.) and correlate with the later Caledonian intrusions of northern England. These episodes of intrusion are separated by late‐Silurian tectonism and define a trend of increasing K 2 O/Na 2 O in the later magmas of the Caledonian orogeny. Miscellaneous palaeomagnetic results from the Borrowdale Volcanic Group, Embleton diorites and Haweswater dolerite are also reported.