Triassic–Jurassic granites on the Lord Howe Rise, northern Zealandia

Mortimer, Nick; Turnbull, Rose; Palin, J. Michael; Tulloch, A. J.; Rollet, Nadège; Hashimoto, Takehiko

doi:10.1080/08120099.2015.1081984

Cited by 16 publications

(35 citation statements)

References 34 publications

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“…The 196‐ to 188‐Ma ages reported here represent an age within the Darran Suite that is not well represented by in situ on‐land plutons (Mortimer et al, , ). Rocks with ages most similar are diorites of the Pahia Intrusives at Cosy Nook (samples CNP and BB30; 203.2 ± 2.8 Ma and 211.0 ± 3.4 Ma; Price et al, ), and a Loch Burn rhyolite (ca.…”

Section: Discussionmentioning

confidence: 69%

“…Adams () reported K/Ar whole rock ages of circa 140, 157 and 186 Ma, for three east‐west striking basalt dikes that cut the granite. Mortimer et al () reported weighted mean zircon and apatite fission track ages of 105 ± 8 Ma and 80 ± 6 Ma, respectively, for Bounty Islands granite.…”

Section: Sample Descriptions and Analytical Resultsmentioning

confidence: 99%

“…Despite the dearth of in situ Early Jurassic plutons, dated clasts of Early Jurassic (ca. 205–170 Ma) granitoids occur (Figure ) in several Jurassic and Cretaceous Zealandian conglomerates (Figure ; Tulloch et al, ; Wandres et al, ; Keeman & Palin, ; Mortimer et al, ). This tentatively suggests that plutons of this age may be more widespread in the Median Batholith and its offshore continuation than previously recognized (as generally indicated by Nelson & Cottle, ).…”

Section: Discussionmentioning

confidence: 99%

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Reconnaissance Basement Geology and Tectonics of South Zealandia

et al. 2019

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We report new U-Pb zircon ages, geochemical and isotopic data for Mesozoic igneous rocks, and new seismic interpretations of mostly submerged South Zealandia (1.5 Mkm 2 ). We use these data, along with existing geological and geophysical data sets, to refine the extent and nature of geological units. Our new 1:25 M geological map of South Zealandia provides a regional framework to investigate the rifting and breakup that formed Zealandia, Earth's most submerged continent. Samples of prerift (pre-100 Ma) plutonic rocks can be matched with on-land New Zealand igneous suites and indicate an east-west strike for the subduction-related 260 to 105-Ma Median Batholith across the Campbell Plateau. The plutonic chronology of formerly contiguous plutonic rocks in West Antarctica reveals similar pulses and lulls to the Median Batholith. Contrary to previous interpretations, the Median Batholith does not coincide with the 1,600-km-long Campbell Magnetic Anomaly System. Instead we interpret the continental magnetic anomalies to represent a mainly mafic igneous unit, whose shape and extent is controlled by synrift structures related to Gondwana breakup. Correlatives of some of these unsampled igneous rocks may be exposed as circa 85 Ma alkalic volcanic rocks on the Chatham Islands. Extension directions varied by up to 65°from 100 to 80 Ma, and we suggest this allowed this large area to thin considerably before final rupture to form new oceanic crust. Synrift (90-80 Ma) structures cut the oroclinal bend in southern South Island and support a pre-early Late Cretaceous age of orocline formation.

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Section: Discussionmentioning

confidence: 69%

Section: Sample Descriptions and Analytical Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Reconnaissance Basement Geology and Tectonics of South Zealandia

et al. 2019

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“…In particular, granites and detrital zircon associated with the Lachlan and New England orogenies of Australia record a Devonian‐Carboniferous and a Permian‐Triassic arc (Adams, Korsch, & Griffin, ; Cawood, ; Cawood & Buchan, ; Cawood et al, ; Jeon et al, ; Kemp et al, ; Li et al, ; Phillips et al, ; Shaanan et al, ; Shaw et al, ; Veevers et al, ). The Median Batholith and volcaniclastic sediments of Zealandia contain a similar record of arc activity for these time periods (Adams et al, ; Adams, Korsch, Griffin, et al, ; Adams, Mortimer, et al, ; Allibone et al, ; Cawood et al, ; Kimbrough et al, ; Mortimer et al, , , ; Tulloch et al, ). Detrital and igneous dates for the southern section of the South American arc compiled by Pepper et al () provide a comprehensive record of near continuous activity with several pulses of increased magma production throughout the Paleozoic and Mesozoic.…”

Section: Discussionmentioning

confidence: 92%

“…Potential sources also exist in Zealandia, where both in situ magmatic rocks and detrital zircons record arc activity throughout the Mesozoic and earlier (Figure b; Elliot, ; Kimbrough et al, ; Adams et al, ; Adams, Korsch, & Griffin, ; Elliot, ; Kimbrough et al, ; Mortimer et al, ). Nevertheless, unexposed/undiscovered magmatic rocks in West Antarctica (e.g., Marie Byrd Land) remain the prevailing volcanic source region hypothesis for volcanic detritus material in the cTAM Beacon Supergroup (Elliot et al, ; Elliot, Fanning, et al, ; Elliot, Larsen, et al, ; Elsner et al, ).…”

Section: Geologic Backgroundmentioning

confidence: 99%

Long‐Term Geochemical and Geodynamic Segmentation of the Paleo‐Pacific Margin of Gondwana: Insight From the Antarctic and Adjacent Sectors

Nelson

Cottle

2017

Tectonics

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Combined zircon geochemistry and geochronology of Mesozoic volcaniclastic sediments of the central Transantarctic Mountains, Antarctica, yield a comprehensive record of both the timing and geochemical evolution of the magmatic arc along the Antarctic sector of the paleo‐Pacific margin of Gondwana. Zircon age populations at 266–183 Ma, 367–328 Ma, and 550–490 Ma correspond to episodic arc activity from the Ediacaran to the Jurassic. Zircon trace element geochemistry indicates a temporal shift from granitoid‐dominated source(s) during Ediacaran to Early Ordovician times to mafic sources in the Devonian through Early Jurassic. Zircon initial εHf shifts to more radiogenic Hf isotope compositions following the Ross Orogeny and is inferred to reflect juvenile crustal growth within an extensional arc system during progressive slab rollback. These new ages and Hf isotopic record are similar to those from the Australian sector, indicating that these regions constituted an ~3,000 km laterally continuous extensional arc from at least the Carboniferous to the Permian. Conversely, the South American sector records enriched zircon Hf isotopic compositions and compressional/advancing arc tectonics during the same time period. Our new data constrain the location of this profound along‐arc geochemical and geodynamic “switch” to the vicinity of the Thurston Island block of West Antarctica.

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Permian rifting and isolation of New Caledonia: Evidence from detrital zircon geochronology

et al. 2018

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The island of New Caledonia is the second largest rock exposure of the continent Zealandia. The New Caledonian basement rocks have been interpreted as representing a late Paleozoic to Mesozoic intra-oceanic arc system that was possibly correlative to contemporaneous terranes in eastern Australia and New Zealand. In order to understand tectonic relationships between the basement rocks of New Caledonia and other eastern Gondwanan terranes, we obtained >2200 new U-Pb ages of detrital zircon grains from New Caledonia. Our new results, combined with a synthesis of previously published geochronological data, show abundant pre-Mesozoic zircon ages, but an absence of Early Permian to Middle Triassic ages, which are characteristic of eastern Gondwana magmatism. The results thus suggest that the

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Triassic–Jurassic granites on the Lord Howe Rise, northern Zealandia

Cited by 16 publications

References 34 publications

Reconnaissance Basement Geology and Tectonics of South Zealandia

Reconnaissance Basement Geology and Tectonics of South Zealandia

Long‐Term Geochemical and Geodynamic Segmentation of the Paleo‐Pacific Margin of Gondwana: Insight From the Antarctic and Adjacent Sectors

Permian rifting and isolation of New Caledonia: Evidence from detrital zircon geochronology

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