Open AccessA high southerly palaeolatitude for Southern Britain in Early Ordovician times: palaeomagnetic data from the Treffgarne Volcanic Formation SW Wales
Author(s) -
Trench A.,
Torsvik T. H.,
Dentith M. C.,
Walderhaug H.,
Traynor J.J.
Publication year - 1992
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1992.tb00840.x
Subject(s) - ordovician , geology , conglomerate , paleontology , volcano , volcanic rock , paleomagnetism , sedimentary rock
SUMMARY A palaeomagnetic pole is reported from late Tremadoc‐early Arenig volcanics of the Treffgarne Volcanic Formation, southwest Wales. This pole, located at N56d̀, E306d̀ ( dp/dm =9/10), implies that Southern Britain was positioned at c . 60d̀S during Early Ordovician times. These data are considered palaeomagnetically reliable based upon a positive intraformational conglomerate test. Comparison with palaeomagnetic results from the southern Laurentian margin suggests the intervening Iapetus Ocean to have reached a width of at least 5000 km at this time. A partial magnetic overprint of Hercynian age is also identified (pole: S42d̀, E346d̀, dp/dm = 5/9) and is correlated with similar remagnetization features across southern and central Wales. Geological indicators of palaeotemperature in the south/central Welsh Basin most likely reflect a Hercynian thermochemical pulse.