The Marguerite Amphibolite and associated rocks in northern Fiordland, New Zealand, contain evide... more The Marguerite Amphibolite and associated rocks in northern Fiordland, New Zealand, contain evidence for retention of Carboniferous metamorphic assemblages through Cretaceous collision of an arc, emplacement of large volumes of mafic magma, high-P metamorphism and then extensional exhumation. The amphibolite occurs as five dismembered aluminous meta-gabbroic xenoliths up to 2 km wide that are enclosed within meta-leucotonalite of the Lake Hankinson Complex. A first metamorphic event (M1) is ...
New Zealand Journal of Geology and Geophysics, Jun 1, 2006
The Fontaine Pluton is a previously undescribed mafic intrusion outcropping at Fontaine Bluff on ... more The Fontaine Pluton is a previously undescribed mafic intrusion outcropping at Fontaine Bluff on the south side of the Carlyon Glacier in southern Victoria Land, Antarctica. It is the southern‐most member of a laterally extensive mafic suite emplaced at mid‐crustal depths during the initial stages of the Ross Orogeny. The pluton comprises recrystal‐lised hornblende‐biotite gabbro, which in places shows well‐defined centimetre to metre scale primary igneous layering. Recrystallised ultramafic enclaves composed of amphibole‐ ...
On the north side of the Mulock Glacier and at Cape Teall in southern Victoria Land, Antarctica, ... more On the north side of the Mulock Glacier and at Cape Teall in southern Victoria Land, Antarctica, deformed greenschist facies Skelton Group metasediments are intruded by the post-kinematic A-type Mulock Granite. Geochemical data indicate that this intrusive complex is similar to A-type granitoids previously described both to the north (Glee Intrusives and Penny Hill Granite), where they form part of the Koettlitz Glacier Alkaline Province, and to the south (Foggydog Granite Suite). A U-Pb zircon date of 546 ± 3 Ma on the Mulock Granite places a minimum constraint on the age, and timing of deformation of the Skelton Group rocks in this area, and indicates that the Mulock Granite was emplaced during the initial stages of the Ross Orogeny. This age also confirms that crystallisation of this granite body was synchronous with that of A-type granitoids from the Royal Society Range to Skelton Glacier area immediately to the north. During the late Neoproterozoic, extension or transtension along this part of the paleo-Pacific margin of Gondwana allowed crustal-scale thinning to occur. This, coupled with the addition of an external heat supply through mafic underplating and/or asthenospheric upwelling, caused lower crustal anatexis and the production of small volumes of A-type granitoid melt. Although the exact nature of this anatectic process remains unclear, it seems probable that melting did not occur under strictly anhydrous conditions, and an external water supply played a crucial role in melt generation.
The Chrystalls Beach Complex is interpreted as an accretionary me´lange within the Otago Schist o... more The Chrystalls Beach Complex is interpreted as an accretionary me´lange within the Otago Schist on the South Island of New Zealand. Its stratigraphic position within the New Zealand Mesozoic accretionary prism is not well constrained, and the terrane affinity of the complex has remained enigmatic. Previous studies have focused on age relationships and sediment geochemistry. In this contribution we present geochemical data for metabasalts within the complex. Two distinctly different basalt compositions are found in the me´lange. Metabasalts outcropping at the northern end of the complex have an inferred mid-ocean ridge affinity, while metabasalts in the central part of the assemblage are suggested to represent ocean island basalts. It is speculated that the northern mid-ocean ridge basalts represent blocks from the crust of a subducting slab, while the ocean island basalts are part of a subducting seamount. These tectonic affinities are in agreement with me´lange formation during sub...
The Marguerite Amphibolite and associated rocks in northern Fiordland, New Zealand, contain evide... more The Marguerite Amphibolite and associated rocks in northern Fiordland, New Zealand, contain evidence for retention of Carboniferous metamorphic assemblages through Cretaceous collision of an arc, emplacement of large volumes of mafic magma, high-P metamorphism and then extensional exhumation. The amphibolite occurs as five dismembered aluminous meta-gabbroic xenoliths up to 2 km wide that are enclosed within meta-leucotonalite of the Lake Hankinson Complex. A first metamorphic event (M1) is ...
New Zealand Journal of Geology and Geophysics, Jun 1, 2006
The Fontaine Pluton is a previously undescribed mafic intrusion outcropping at Fontaine Bluff on ... more The Fontaine Pluton is a previously undescribed mafic intrusion outcropping at Fontaine Bluff on the south side of the Carlyon Glacier in southern Victoria Land, Antarctica. It is the southern‐most member of a laterally extensive mafic suite emplaced at mid‐crustal depths during the initial stages of the Ross Orogeny. The pluton comprises recrystal‐lised hornblende‐biotite gabbro, which in places shows well‐defined centimetre to metre scale primary igneous layering. Recrystallised ultramafic enclaves composed of amphibole‐ ...
On the north side of the Mulock Glacier and at Cape Teall in southern Victoria Land, Antarctica, ... more On the north side of the Mulock Glacier and at Cape Teall in southern Victoria Land, Antarctica, deformed greenschist facies Skelton Group metasediments are intruded by the post-kinematic A-type Mulock Granite. Geochemical data indicate that this intrusive complex is similar to A-type granitoids previously described both to the north (Glee Intrusives and Penny Hill Granite), where they form part of the Koettlitz Glacier Alkaline Province, and to the south (Foggydog Granite Suite). A U-Pb zircon date of 546 ± 3 Ma on the Mulock Granite places a minimum constraint on the age, and timing of deformation of the Skelton Group rocks in this area, and indicates that the Mulock Granite was emplaced during the initial stages of the Ross Orogeny. This age also confirms that crystallisation of this granite body was synchronous with that of A-type granitoids from the Royal Society Range to Skelton Glacier area immediately to the north. During the late Neoproterozoic, extension or transtension along this part of the paleo-Pacific margin of Gondwana allowed crustal-scale thinning to occur. This, coupled with the addition of an external heat supply through mafic underplating and/or asthenospheric upwelling, caused lower crustal anatexis and the production of small volumes of A-type granitoid melt. Although the exact nature of this anatectic process remains unclear, it seems probable that melting did not occur under strictly anhydrous conditions, and an external water supply played a crucial role in melt generation.
The Chrystalls Beach Complex is interpreted as an accretionary me´lange within the Otago Schist o... more The Chrystalls Beach Complex is interpreted as an accretionary me´lange within the Otago Schist on the South Island of New Zealand. Its stratigraphic position within the New Zealand Mesozoic accretionary prism is not well constrained, and the terrane affinity of the complex has remained enigmatic. Previous studies have focused on age relationships and sediment geochemistry. In this contribution we present geochemical data for metabasalts within the complex. Two distinctly different basalt compositions are found in the me´lange. Metabasalts outcropping at the northern end of the complex have an inferred mid-ocean ridge affinity, while metabasalts in the central part of the assemblage are suggested to represent ocean island basalts. It is speculated that the northern mid-ocean ridge basalts represent blocks from the crust of a subducting slab, while the ocean island basalts are part of a subducting seamount. These tectonic affinities are in agreement with me´lange formation during sub...
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