TY - JOUR
T1 - First magmatism in the New England Batholith, Australia
T2 - Forearc and arc-back-arc components in the Bakers Creek Suite gabbros
AU - McKibbin, Seann J.
AU - Landenberger, Bill
AU - Mark Fanning, C.
N1 - Publisher Copyright:
© 2017 The Author(s).
PY - 2017/4/5
Y1 - 2017/4/5
N2 - The New England Orogen, eastern Australia, was established as an outboard extension of the Lachlan Orogen through the migration of magmatism into forearc basin and accretionary prism sediments. Widespread S-type granitic rocks of the Hillgrove and Bundarra supersuites represent the first pulse of magmatism, followed by I-A nd A-types typical of circum-Pacific extensional accretionary orogens. Associated with the former are a number of small tholeiite-gabbroic to intermediate bodies of the Bakers Creek Suite, which sample the heat source for production of granitic magmas and are potential tectonic markers indicating why magmatism moved into the forearc and accretionary complexes rather than rifting the old Lachlan Orogen arc. The Bakers Creek Suite gabbros capture an early (∼305Ma) forearc basalt-like component with low Th/Nb and with high Y/Zr and Ba/La, recording melting in the mantle wedge with little involvement of a slab flux and indicating forearc rifting. Subsequently, arc-back-arc like gabbroic magmas (305-304Ma) were emplaced, followed by compositionally diverse magmatism leading up to the main S-type granitic intrusion (∼290Ma). This trend in magmatic evolution implicates forearc and other mantle wedge melts in the heating and melting of fertile accretion complex sediments and relatively long (∼10Myr) timescales for such melting.
AB - The New England Orogen, eastern Australia, was established as an outboard extension of the Lachlan Orogen through the migration of magmatism into forearc basin and accretionary prism sediments. Widespread S-type granitic rocks of the Hillgrove and Bundarra supersuites represent the first pulse of magmatism, followed by I-A nd A-types typical of circum-Pacific extensional accretionary orogens. Associated with the former are a number of small tholeiite-gabbroic to intermediate bodies of the Bakers Creek Suite, which sample the heat source for production of granitic magmas and are potential tectonic markers indicating why magmatism moved into the forearc and accretionary complexes rather than rifting the old Lachlan Orogen arc. The Bakers Creek Suite gabbros capture an early (∼305Ma) forearc basalt-like component with low Th/Nb and with high Y/Zr and Ba/La, recording melting in the mantle wedge with little involvement of a slab flux and indicating forearc rifting. Subsequently, arc-back-arc like gabbroic magmas (305-304Ma) were emplaced, followed by compositionally diverse magmatism leading up to the main S-type granitic intrusion (∼290Ma). This trend in magmatic evolution implicates forearc and other mantle wedge melts in the heating and melting of fertile accretion complex sediments and relatively long (∼10Myr) timescales for such melting.
UR - http://www.scopus.com/inward/record.url?scp=85017156302&partnerID=8YFLogxK
U2 - 10.5194/se-8-421-2017
DO - 10.5194/se-8-421-2017
M3 - Article
AN - SCOPUS:85017156302
SN - 1869-9510
VL - 8
SP - 421
EP - 434
JO - Solid Earth
JF - Solid Earth
IS - 2
ER -