Ar‐Ar dating of K‐feldspar in low grade metamorphic rocks: Example of an exhumed Mesozoic accretionary wedge and forearc, South Island, New Zealand

Mortimer, Nick; McLaren, Sandra; Dunlap, W. J.

doi:10.1029/2011tc003057

Cited by 31 publications

(24 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After deposition during the Triassic to Early Cretaceous, the rocks of the present basement of North Island were deformed in the accretionary wedge on the eastern Gondwana margin (Figure a) [after Mortimer , ]. Exhumation of these Mesozoic accretionary terranes has been previously studied in the Otago Schist at South Island [e.g., Mortimer et al ., ; Nishimura et al ., ]. Little et al .…”

Section: Interpretation and Discussionmentioning

confidence: 98%

Thermal history and exhumation of basement rocks from Mesozoic to Cenozoic subduction cycles, central North Island, New Zealand

et al. 2014

View full text Add to dashboard Cite

A new thermochronological study of the basement rocks of the central North Island, New Zealand, records thermal and exhumation histories related to two subduction cycles since the latest Jurassic. The basement comprises metasedimentary terranes accreted onto eastern Gondwana during Mesozoic subduction. Since the Oligocene, these terranes have been located on the hanging wall of the Hikurangi subduction margin, overriding the Pacific Plate. Results of zircon fission track (121-264 Ma) analysis yield detrital or slightly reset ages; apatite fission track (19.8-122 Ma) and (U-Th-Sm)/He (10.3-95.2 Ma) ages are fully reset. Results from inverse thermal history modeling of the data of individual and stacked samples imply the following: (1) after their accretion, the basement rocks were cooled and exhumed to shallow depths of the crust in the Early Cretaceous (by~150-135 Ma). This was followed by an episode of reheating until~100 Ma, which we interpret to be the result of burial by sedimentation above the accretionary wedge during extensional deformation caused by continued underplating and thickening of the wedge from beneath. (2) From 100 Ma, our data indicate thermotectonic quiescence until the Oligocene (~27 Ma). (3) During initiation of the Hikurangi Margin, the fore-arc proto-Axial Ranges began to exhume during the late Oligocene to early Miocene (~27-20 Ma). Subduction-triggered unroofing removed~1.2-2.8 km of overburden, most of which was probably the less lithified passive margin sediments. (4) Along the western central North Island, the exhumational response to the Hikurangi subduction was limited, with a total magnitude of erosion <1.5 km in the Cenozoic.

show abstract

Section: Interpretation and Discussionmentioning

confidence: 98%

Thermal history and exhumation of basement rocks from Mesozoic to Cenozoic subduction cycles, central North Island, New Zealand

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Thermobarometric studies indicate that the greenschist facies rocks reached ~400°C at 0.8–1.0 GPa (Mortimer, ; Yardley, ) between c . 180 and 140 Ma (Gray & Foster, ; Mortimer, McLaren, & Dunlap, ). The 40 Ar/ 39 Ar ages of ~110–90 Ma in the core represent exhumation‐driven cooling (Gray & Foster, ).…”

Section: Geological Settingmentioning

confidence: 99%

“…The metamorphic facies of the Otago Schist display a dome-like distribution with the flanks recording prehnite-pumpellyite facies and the core preserving upper greenschist facies assemblages (Bishop, 1972;Mortimer, 2000; Figure 1). Thermobarometric studies indicate that the greenschist facies rocks reached~400°C at 0.8-1.0 GPa (Mortimer, 2000;Yardley, 1982) between c. 180 and 140 Ma (Gray & Foster, 2004;Mortimer, McLaren, & Dunlap, 2012). The 40 Ar/ 39 Ar ages of~110-90 Ma in the core represent exhumation-driven cooling (Gray & Foster, 2004).…”

Section: Geological Settingmentioning

confidence: 99%

High‐ to ultrahigh‐temperature metamorphism in the lower crust: An example resulting from Hikurangi Plateau collision and slab rollback in New Zealand

Jacob

Scott

Turnbull

et al. 2017

Journal Metamorphic Geology

View full text Add to dashboard Cite

Lower crustal xenoliths erupted from an intraplate diatreme reveal that a portion of the New Zealand Gondwana margin experienced high‐temperature (HT) to ultrahigh‐temperature (UHT) granulite facies metamorphism just after flat slab subduction ceased at c. 110–105 Ma. P–T calculations for garnet–orthopyroxene‐bearing felsic granulite xenoliths indicate equilibration at ~815 to 910°C and 0.7 to 0.8 GPa, with garnet‐bearing mafic granulite xenoliths yielding at least 900°C. Supporting evidence for the attainment of HT and UHT conditions in felsic granulite comes from re‐integration of exsolution in feldspar (~900–950°C at 0.8 GPa), Ti‐in‐zircon thermometry on Y‐depleted overgrowths on detrital zircon grains (932°C ± 24°C at aTiO2 = 0.8 ± 0.2), and correlation of observed assemblages and mineral compositions with thermodynamic modelling results (≥850°C at 0.7 to 0.8 GPa). The thin zircon overgrowths, which were mainly targeted by drilling through the cores of grains, yield a U–Pb pooled age of 91.7 ± 2.0 Ma. The cause of Late Cretaceous HT‐UHT metamorphism on the Zealandia Gondwana margin is attributed to collision and partial subduction of the buoyant oceanic Hikurangi Plateau in the Early Cretaceous. The halt of subduction caused the fore‐running shallowly dipping slab to rollback towards the trench position and permitted the upper mantle to rapidly increase the geothermal gradient through the base of the extending (former) accretionary prism. This sequence of events provides a mechanism for achieving regional HT–UHT conditions in the lower crust with little or no sign of this event at the surface.

show abstract

“…The older Permian part is related to an intraoceanic arc, possibly the Brook Street Terrane, but the younger part is linked to a continental margin arc , inferred to be the Median Batholith. Basin sedimentary rocks are 9-13 km thick and are mainly marine, well-bedded shelf and slope deposits with tuffs (Mortimer et al 2012).…”

Section: Inboard Terranesmentioning

confidence: 99%

“…Abbreviations: 3KR, Three Kings Ridge; B-G-SB, Bowen-Gunnedah-Sydney basins; CFZ, Cook Fracture Zone; DO, Delamerian Orogen; DR, Dampier Ridge; LO, Lachlan Orogen; LA, Loyalty Arc; LR, Loyalty Ridge; MB, Middleton Basin; MO, Mossman Orogen; NB, New Britain; NEO, New England Orogen; NLB, North Loyalty Basin; NR, Norfolk Ridge; NST, North Solomons Trench; SCT, San Cristobal Trench; SLB, South Loyalty Basin; TB, Taranaki Basin; TO, Thomson Orogen; VMFZ, Vening Meinesz Fracture Zone; VA, Vanuatu Arc (former New Hebrides Arc); VT, Vanuatu Trench. Extinct Cretaceous Trench adapted from Mortimer et al (2012). [Colour online.…”

Section: Introductionmentioning

confidence: 99%

Different styles of modern and ancient non-collisional orogens and implications for crustal growth: a Gondwanaland perspective

2016

View full text Add to dashboard Cite

Non-collisional, convergent margin orogens are generally called accretionary orogens, although there may not have been horizontal accretion across the plate boundary. We revive the term non-collisional orogen and use a Gondwanaland perspective to discuss different types. On the northern margin of the Australian Plate, the New Guinea non-collisional, accretionary orogen was formed by large-scale terrane accretion across an advancing plate margin. On the eastern margin, the Southwest Pacific Orogen is a non-collisional and non-accretionary orogen, involving virtually no horizontal transfer of material across its eastward-retreating plate boundary. In the Tasmanides, the Lachlan Orogen, commonly described as an accretionary orogen, is another non-collisional, non-accretionary orogen developed behind the plate margin after major Cambrian rollback, with resultant backarc basins filled mainly by quartz-rich turbidites subsequently recycled. The outboard New England Orogen is a non-collisional but accretionary orogen, marked by the frontal accretion of continental margin arc detritus, subsequently recycled into younger arcs. The Permian to Cretaceous Rangitata Orogen of New Zealand is an ?oblique non-collisional, accretionary orogen in which Permian-Triassic sediments of the accretionary wedge have no link with inboard (near) arc terranes. Late Jurassic to Cretaceous parts were sourced by a combination of first cycle volcanogenic detritus passing through the forearc basin together with recycling of the exhumed parts of the wedge. All non-collisional orogens involve continental growth, but only the New England Orogen and to a lesser extent the New Guinea Orogen involve significant crustal growth.

show abstract

Ar‐Ar dating of K‐feldspar in low grade metamorphic rocks: Example of an exhumed Mesozoic accretionary wedge and forearc, South Island, New Zealand

Cited by 31 publications

References 80 publications

Thermal history and exhumation of basement rocks from Mesozoic to Cenozoic subduction cycles, central North Island, New Zealand

Thermal history and exhumation of basement rocks from Mesozoic to Cenozoic subduction cycles, central North Island, New Zealand

High‐ to ultrahigh‐temperature metamorphism in the lower crust: An example resulting from Hikurangi Plateau collision and slab rollback in New Zealand

Different styles of modern and ancient non-collisional orogens and implications for crustal growth: a Gondwanaland perspective

Contact Info

Product

Resources

About