Extensional and magmatic nature of the Campbell Plateau and Great South Basin from deep crustal studies

Grobys, Jan; Gohl, Karsten; Uenzelmann-Neben, Gabriele; Davy, Bryan; Barker, D. H. N.

doi:10.1016/j.tecto.2008.05.003

Cited by 39 publications

(34 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The source of this is both thick high‐density lower crust and a thick mantle root (see section 4.3) [ Stern et al ., ; Bourguinon et al ., ], as a consequence of Cenozoic lithospheric shortening [ Stern et al ., ]. Taken together with the evidence for subdued relief at or below sea level around ∼23 Ma, the previous analysis indicates that the initial crustal thickness throughout southern South Island was not thicker than that at the coast today (i.e., 25–32 km, thickening toward the south), and most likely thinner (23–27 km), comparable to the crustal thickness farther offshore where there is no evidence for Cenozoic deformation [ Godfrey et al ., ; Scherwath et al ., ; Grobys et al ., ]. Estimates of initial crustal thickness for each transect, used to calculate post 23 Ma crustal thickening and shortening (section 2.2.3), are shown in Figure b.…”

Section: Crustal Thickening Beneath the Southern Alpsmentioning

confidence: 99%

“…Relative plate motions in the New Zealand region during the Cenozoic are determined from magnetic anomalies and fracture zones in the sea floor between Antarctica and the Australian and Pacific Plates, together with the orientation of fracture zones to the south of New Zealand, created during Eocene-Oligocene sea floor spreading between the Australian and Pacific plates [Sutherland, 1995;Sutherland et al, 2000;Cande and Stock, 2004;Keller, 2004;Croon et al, 2008;Barker et al, 2009;Sandwell et al 2014] (S. Lamb and E. Smith, Calculating Cenozoic Australia-Pacific stage Euler poles in the New Zealand region, manuscript in preparation, 2015). Cande and Stock [2004] revised the Australian-Pacific Plate rotation poles determined by Walcott [1998], which were based on lower resolution fracture zone data for sea floor spreading between Australia and Antarctica [Royer and Sandwell, 1989].…”

Section: Cenozoic Plate Motions In the New Zealand Regionmentioning

confidence: 99%

See 1 more Smart Citation

Continent‐scale strike‐slip on a low‐angle fault beneath New Zealand's Southern Alps: Implications for crustal thickening in oblique collision zones

Lamb

Smith

Stern

et al. 2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

New Zealand's Southern Alps lie adjacent to the continent-scale dextral strike-slip Alpine Fault, on the boundary between the Pacific and Australian plates. We show with a simple 2-D model of crustal balancing that the observed crustal root and erosion (expressed as equivalent crustal shortening) is up to twice that predicted by the orthogonal plate convergence since 11 Ma, and even since 23 Ma when the Alpine Fault formed. We consider two explanations for this, involving a strong component of motion along the length of the plate-boundary zone. Geophysical data indicate that the Alpine Fault has a listric geometry, flattening at mid crustal levels, and has accommodated sideways underthrusting of Australian plate crust beneath Pacific plate crust. The geometry of the crustal root, together with plate reconstructions, requires the underthrust crust to be the hyperextended part of an asymmetric rift system which formed over 500 km farther south during the Eocene-the narrow remnant part today forms the western margin of the Campbell Plateau. At 10 Ma, the hyperextended margin underwent shallow subduction in the Puysegur subduction zone, and then was dragged over 300 km along the length of the Southern Alps beneath a low-angle (<208) section of the Alpine Fault. We speculate that prior to 10 Ma, more distributed lower crustal shortening and thickening occurred beneath the Southern Alps, accommodating southward extrusion of continental crust in the northern part of the plate boundary zone, providing a mechanism for clockwise rotation of the Hikurangi margin.

show abstract

Section: Crustal Thickening Beneath the Southern Alpsmentioning

confidence: 99%

Section: Cenozoic Plate Motions In the New Zealand Regionmentioning

confidence: 99%

Continent‐scale strike‐slip on a low‐angle fault beneath New Zealand's Southern Alps: Implications for crustal thickening in oblique collision zones

Lamb

Smith

Stern

et al. 2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…Under the Rockall Bank, this layer is believed to be serpentinized upper mantle (O'Reilly et al, 1996). For the continental fragments off the Australian margin, the high velocity lower layer is interpreted as mafic underplating (Grobys et al, 2009). Mostly, the high velocity seismic layer is found below the surrounding basins with oceanic or thinned continental crust.…”

Section: Continental Fragments and Microcontinents: Crustal Structurementioning

confidence: 99%

“…Bulk densities are also reported from studies where the authors combined gravity and seismic data to determine crustal density. References are (1) Funck et al (2008), (2) Grobys et al (2007), (3) Cooper et al (1981), (4) Grobys et al (2009), (5) Borissova et al (2003), (6) Klingelhoefer et al (2007), (7) Funck (2003), (8) Gerlings et al (2011), (9) Fowler et al (1989), (10) Breivik et al (2012), (11) Lebedeva-Ivanova et al (2006), (12) Morewood et al (2005), (13) Vogt et al (1998), and (14) Collier et al (2009 In the geological record, large volumes of crustal accretion are carried out by the collision of composite terranes or continental fragments onto continents (Vink et al, 1984). In North America, the amalgamation of the Wrangellia and Stikinia terranes resulted in a ribbon continent (SABIYA) that was ∼ 8000 km long and ∼ 500 km wide (Johnston, 2001).…”

Section: Composite Terranesmentioning

confidence: 99%

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Tetreault

Buiter

2014

Solid Earth

View full text Add to dashboard Cite

Abstract. Allochthonous accreted terranes are exotic geologic units that originated from anomalous crustal regions on a subducting oceanic plate and were transferred to the overriding plate by accretionary processes during subduction. The geographical regions that eventually become accreted allochthonous terranes include island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents. These future allochthonous terranes (FATs) contribute to continental crustal growth, subduction dynamics, and crustal recycling in the mantle. We present a review of modern FATs and their accreted counterparts based on available geological, seismic, and gravity studies and discuss their crustal structure, geological origin, and bulk crustal density. Island arcs have an average crustal thickness of 26 km, average bulk crustal density of 2.79 g cm −3 , and three distinct crustal units overlying a crust-mantle transition zone. Oceanic plateaus and submarine ridges have an average crustal thickness of 21 km and average bulk crustal density of 2.84 g cm −3 . Continental fragments presently on the ocean floor have an average crustal thickness of 25 km and bulk crustal density of 2.81 g cm −3 . Accreted allochthonous terranes can be compared to these crustal compilations to better understand which units of crust are accreted or subducted. In general, most accreted terranes are thin crustal units sheared off of FATs and added onto the accretionary prism, with thicknesses on the order of hundreds of meters to a few kilometers. However, many island arcs, oceanic plateaus, and submarine ridges were sheared off in the subduction interface and underplated onto the overlying continent. Other times we find evidence of terrane-continent collision leaving behind accreted terranes 25-40 km thick. We posit that rheologically weak crustal layers or shear zones that were formed when the FATs were produced can be activated as detachments during subduction, allowing parts of the FAT crust to accrete and others to subduct. In many modern FATs on the ocean floor, a sub-crustal layer of high seismic velocities, interpreted as ultramafic material, could serve as a detachment or delaminate during subduction.

show abstract

“…Furthermore, many authors postulate that the lower crust of oceanic plateaus, submarine ridges, and island arcs is an ultramafic cumulate layer that serves as a detachment layer during accretion [ Behn and Kelemen , 2006; Schubert and Sandwell , 1989; Mann and Taira , 2004]. Continental fragments are typically rifted off blocks from continents (e.g., Campbell Plateau: Grobys et al [2009], Rockall Bank: Klingelhoefer et al [2005], and the Seychelles: Collier et al [2009]), and therefore have pre‐existing weaknesses from extension. This paper presents a first‐order examination of terrane accretion with respect to buoyancy, rheology, and internal strength of the FAT.…”

Section: Introductionmentioning

confidence: 99%

Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and continental fragments in subduction zones

Tetreault

Buiter

2012

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Crustal growth at convergent margins can occur by the accretion of future allochthonous terranes (FATs), such as island arcs, oceanic plateaus, submarine ridges, and continental fragments. Using geodynamic numerical experiments, we demonstrate how crustal properties of FATs impact the amount of FAT crust that is accreted or subducted, the type of accretionary process, and the style of deformation on the overriding plate. Our results show that (1) accretion of crustal units occurs when there is a weak detachment layer within the FAT, (2) the depth of detachment controls the amount of crust accreted onto the overriding plate, and (3) lithospheric buoyancy does not prevent FAT subduction during constant convergence. Island arcs, oceanic plateaus, and continental fragments will completely subduct, despite having buoyant lithospheric densities, if they have rheologically strong crusts. Weak basal layers, representing pre-existing weaknesses or detachment layers, will either lead to underplating of faulted blocks of FAT crust to the overriding plate or collision and suturing of an unbroken FAT crust. Our experiments show that the weak, ultramafic layer found at the base of island arcs and oceanic plateaus plays a significant role in terrane accretion. The different types of accretionary processes also affect deformation and uplift patterns in the overriding plate, trench migration and jumping, and the dip of the plate interface. The resulting accreted terranes produced from our numerical experiments resemble observed accreted terranes, such as the Wrangellia Terrane and Klamath Mountain terranes in the North American Cordilleran Belt.Citation: Tetreault, J. L., and S. J. H. Buiter (2012), Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and continental fragments in subduction zones,

show abstract

Extensional and magmatic nature of the Campbell Plateau and Great South Basin from deep crustal studies

Cited by 39 publications

References 50 publications

Continent‐scale strike‐slip on a low‐angle fault beneath New Zealand's Southern Alps: Implications for crustal thickening in oblique collision zones

Continent‐scale strike‐slip on a low‐angle fault beneath New Zealand's Southern Alps: Implications for crustal thickening in oblique collision zones

Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments

Geodynamic models of terrane accretion: Testing the fate of island arcs, oceanic plateaus, and continental fragments in subduction zones

Contact Info

Product

Resources

About