10.6084/m9.figshare.3453941.v1
Taylor M. Kilian
Taylor M.
Kilian
Wouter Bleeker
Wouter
Bleeker
Kevin Chamberlain
Kevin
Chamberlain
David A. D. Evans
David A. D.
Evans
Brian Cousens
Brian
Cousens
Palaeomagnetism, geochronology and geochemistry of the Palaeoproterozoic Rabbit Creek and Powder River dyke swarms: implications
for Wyoming in supercraton Superia
Geological Society of London
2016
Snowy Pass Supergroups
palaeomagnetic pole
rift basin development
Wind River uplifts
Ga
Superior craton
Ma
Rabbit Creek swarm
Wyoming craton
TIMS
Palaeoproterozoic Rabbit Creek
Powder River dyke swarms
Rabbit Creek dykes
Geology
2016-06-21 11:47:24
Journal contribution
https://geolsoc.figshare.com/articles/journal_contribution/Palaeomagnetism_geochronology_and_geochemistry_of_the_Palaeoproterozoic_Rabbit_Creek_and_Powder_River_dyke_swarms_implications___for_Wyoming_in_supercraton_Superia/3453941
<p>It is likely that Archaean cratons of Laurentia had different palaeogeographic histories prior to their amalgamation. New
palaeomagnetic, geochronological and geochemical evidence supports a reconstruction of the Wyoming craton adjacent to the
southern margin of the Superior craton at 2.16 Ga, before rifting (<em>c.</em> 2.1–2.0 Ga) and eventual reamalgamation after the Hudsonian Orogeny (<em>c.</em> 1.8 Ga). U–Pb ages (TIMS on baddeleyite) from five dykes yield two groups of ages at <em>c.</em> 2164 and 2155 Ma. The younger group of ages defines the Rabbit Creek swarm at 2161–2152 Ma and precisely dates its palaeomagnetic
pole. Two large and differentiated dykes (>100 m) in the Bighorn and Wind River uplifts are geographically related to the
Rabbit Creek swarm but have slightly different orientations and yield slightly older ages at 2171–2157 Ma. These dykes may
be parts of a single intrusion (the ‘Great Dyke of Wyoming’) that spans over 200 km between uplifts, possibly representing
a different magmatic event. This older event does not have enough distinct intrusions to provide a correctly averaged palaeomagnetic
pole, but correlates with magmatism in the Superior craton and has a palaeomagnetic remanence comparable to the Rabbit Creek
dykes. With minor tilt corrections, the palaeomagnetic data from the Rabbit Creek swarm and Powder River–South Pass dykes
support a reconstruction of the southeastern Wyoming craton against the southern Superior craton. This fit juxtaposes the
Palaeoproterozoic Huronian and Snowy Pass Supergroups along two passive margins that experienced a prolonged period of mafic
magmatism (>100 myr) and rift basin development. Although there are slight geochemical variations across the Rabbit Creek
swarm, all dykes fit into two distinct groups that are independently dated and internally consistent.
</p>