Geochemical evolution of Dalradian metavolcanic rocks: implications for the break-up of the Rodinia supercontinent
D.J. Fettes
R. Macdonald
J.G. Fitton
D. Stephenson
M.R. Cooper
10.6084/m9.figshare.3452873
https://geolsoc.figshare.com/articles/journal_contribution/Geochemical_evolution_of_Dalradian_metavolcanic_rocks_implications_for_the_break-up_of_the_Rodinia_supercontinent/3452873
<p>Neoproterozoic basaltic magmatism in the Dalradian Supergroup of Scotland and Ireland was associated with the break-up of
the Rodinia supercontinent. Magmas were erupted in rift-related basins along a strike length of at least 700 km and during
a time period of <em>c</em>. 80 Ma. New major and trace element analyses of metabasalts from several formations are presented to trace the variations
in magma compositions in time and space. The primary magmas resulted from variable degrees of mixing of melts derived from
mantle sources similar to those of normal and enriched mid-ocean ridge basalts; some younger lavas also show evidence of contamination
with continental crust. In contrast to speculations about magmatism elsewhere in Rodinia, the evidence here suggests that
there was no involvement of a mantle plume in basalt generation. For example, the Scottish promontory of Laurentia drifted
rapidly southwards through <em>c</em>. 25° over the duration of the magmatism, with no evidence of significant elevation above sea level, as might be expected
from involvement of a plume. Generation of the primary magmas might have taken place predominantly through decompression melting
in depleted upper mantle containing enriched streaks and blobs. Both the Dalradian lithostratigraphy and the metabasaltic
compositions are consistent with extreme lithospheric stretching and possibly rupture during the earliest phase of magmatism,
whereas generation of later magmatism appears to have been associated with major fault systems, possibly on a foundering continental
margin.
</p>
2016-06-21 10:43:07
magma compositions
show evidence
strike length
metabasaltic compositions
Dalradian Supergroup
Dalradian lithostratigraphy
involvement
700 km
fault systems
trace element analyses
sea level
time period
Dalradian metavolcanic rocks
Rodinia supercontinent
Geochemical evolution
basalt generation
mantle plume
80 Ma
Rodinia supercontinent Neoproterozoic basaltic magmatism
Scottish promontory
mantle sources
Geology