Transpressional development of the Australia‐Pacific boundary through southern South Island, New Zealand: Constraints from Miocene‐Pliocene sediments, Waiho‐1 borehole, South Westland

Sutherland, Rupert

doi:10.1080/00288306.1996.9514709

Cited by 90 publications

(79 citation statements)

References 52 publications

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“…However, total shortening across the Alpine Fault is only c. 90 km in the last 6 m.y. (Walcott 1998), there is no geophysical evidence for buried ophiolitic Maitai Terrane rocks (e.g., magnetic anomalies), and Maitai Terrane clasts are rare or absent in late Cenozoic sediments (e.g., Sutherland 1996). Further, the fault becomes almost pure strike-slip at its northern and southern ends, and has 100 km of demonstrated strike-slip motion since the Pliocene Bishop et al 1985;Kimbrough et al 1994;Mortimer 1995;Mortimer et al 1997).…”

Section: The Alpine Fault and New Zealand Basement Geologymentioning

confidence: 99%

Cenozoic bending of New Zealand basement terranes and Alpine Fault displacement: A brief review

Sutherland¹

1999

New Zealand Journal of Geology and Geophysics

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149

181

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It is now possible to accurately reconstruct late Eocene-Recent positions of the Australian plate with respect to the Pacific plate. Rates of plate displacement through New Zealand were slow in Eocene-Oligocene time, and increased rapidly in Miocene time as the pole of rotation migrated southeast. Reconstruction of Maitai Terrane rocks suggests they had a smooth and continuously curved geometry through New Zealand in late Eocene time, which was probably similar to their Late Cretaceous configuration. This analysis implies that most or all Alpine Fault offset occurred after 45 Ma, and suggests about half the Eocene-Recent plate displacement was partitioned onto the Alpine Fault, and half was accommodated by distributed crustal shear. Estimates of Pliocene and Quaternary Alpine Fault displacement rate suggest the proportion of plate boundary displacement partitioned onto the Alpine Fault may have increased with time, displacement rate, and total displacement.

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Section: The Alpine Fault and New Zealand Basement Geologymentioning

confidence: 99%

Cenozoic bending of New Zealand basement terranes and Alpine Fault displacement: A brief review

Sutherland¹

1999

New Zealand Journal of Geology and Geophysics

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149

181

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“…The Southern Alps of New Zealand is a prominent mountain range resulting from ongoing oblique thrusting of Pacific plate crust over the Australian plate along the Alpine Fault (Sutherland, 1996). Although this region was under compression for much of Miocene time, geological evidence shows that orogenic uplift initiated at various locations between 8-7 Ma and 5 Ma (King, 2000).…”

Section: Evidence For a Clockwise Rotation Of Pacific Plate Motion Atmentioning

confidence: 99%

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Austermann¹,

Ben‐Avraham²,

Bird³

et al. 2011

Earth and Planetary Science Letters

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Editor: Y. Ricard Keywords:Pacific plate motion plate driving forces slab detachment oceanic plateau collision northern Melanesian arc Studies have documented several rapid changes along the Pacific-North American, Pacific-Antarctic and Pacific-Australian plate boundaries in latest Miocene to earliest Pliocene time consistent with a sudden clockwise rotation of Pacific plate velocity relative to hotspots during this period. We test the hypothesis that this change in plate motion was initiated by cessation of subduction along the northern Melanesian arc due to the collision between the arc and the Ontong Java plateau. This hypothesis has long been formulated but never tested quantitatively. We use a geomechanical model of the lithosphere to determine the changes in plate boundary forces that are necessary to obtain the observed change in the Pacific plate motion. Our model results show that the change in motion can be explained by a clockwise rotation of the slab-related (basal-strength) component of plate driving force. The change of slab-related force from a post-6 Ma to a pre-6 Ma setting is perpendicular to the arc and points towards the Australian plate. The force per unit length is in the range of currently accepted values for subduction zones. Since there have been no other relevant changes at subduction zones along the Pacific plate boundary during the latest Miocene, we relate this change in slab-related force to the former southward-dipping Pacific plate slab along the northern Melanesian arc system which is now detached. Our model results suggest that rapid changes in plate motion can be triggered by slab detachment, with consequences for plate boundary processes even at great distances from the event.

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“…1) (Turnbull et al 1975). If the type 1 and type 3 Nokomai garnets are derived from northwest Otago schist, then alternative transport mechanisms are required to get them into the Nokomai valley, as those source rocks were not exhumed until well after the marine transgression (Adams 1981;Sutherland 1996).…”

Section: Garnetsmentioning

confidence: 99%

Au‐Ag‐Hg and Au‐Ag alloys in Nokomai and Nevis valley placers, northern Southland and Central Otago, New Zealand, and their implications for placer‐source relationships

Youngson

Wopereis²,

Kerr

et al. 2002

New Zealand Journal of Geology and Geophysics

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Gold in Quaternary placers in the Nevis and Nokomai valleys is dominantly a-phase Au-Ag-Hg alloy (c.<10 wt% each of Ag and Hg) with subordinate Au-Ag alloy. The α-Au-Ag-Hg alloy is typically coarse grained (up to 2 cm), angular, and rarely flattened or folded. Crystalline texture, quartz intergrowths, and psuedo-hexagonal crystal pluck cavities are common. Fluvial transport distance estimates based on maximum flatness index of Au-Ag-Hg alloy particles are typically <10-20 km. Coarse (up to 2 cm) crystalline cinnabar is commonly associated with the AuAg-Hg alloy, and both were probably derived from hydrothermal sources in western tributaries of the upper Nevis River and eastern tributaries of the upper Nokomai River. These sources are possibly related to strands of the Nevis-Cardrona Fault System. Secondary Au-Ag-Hg alloy with up to 38 wt% Hg occurs locally in the lower Nokomai alluvial plain, where it coats or cements detrital α-phase AuAg-Hg and Au-Ag alloy particles. The secondary Au-AgHg alloy has formed by diffusion between detrital gold particles and liquid Hg that is either natural or derived from local breakdown of cinnabar.Au-Ag alloy dominates over Au-Ag-Hg alloy in the lower half of the lower Nokomai alluvial plain and in the gravel of a Pleistocene perched channel incised into pumpellyiteactinolite facies semischist basement adjacent to the plain. The Au-Ag alloy is rounded and commonly flattened and folded. Crystalline texture, quartz intergrowths, and pluck cavities are rare in the Au-Ag alloy, and a fluvial transport distance of 25-40 km is estimated from maximum flatness index. Au-Ag alloy, three types of garnet, magnetite, clinozoisite, and well-foliated schist boulders in the abandoned channel gravel are allochthonous. They were derived from greenschist facies schist and sedimentary sources many tens of kilometres north of the Nokomai catchment, and transported either in Wakatipu Glacier till or fluvioglacial outwash gravel that entered the Nokomai valley via Nokomai Saddle, the confluence with the Mataura River, or both. Mercury minerals in hydrothermal deposits within the Otago Schist appear to be restricted to the Caples Terrane. A gold-mercury association is proposed for the Caples Terrane.

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Transpressional development of the Australia‐Pacific boundary through southern South Island, New Zealand: Constraints from Miocene‐Pliocene sediments, Waiho‐1 borehole, South Westland

Cited by 90 publications

References 52 publications

Cenozoic bending of New Zealand basement terranes and Alpine Fault displacement: A brief review

Cenozoic bending of New Zealand basement terranes and Alpine Fault displacement: A brief review

Quantifying the forces needed for the rapid change of Pacific plate motion at 6Ma

Au‐Ag‐Hg and Au‐Ag alloys in Nokomai and Nevis valley placers, northern Southland and Central Otago, New Zealand, and their implications for placer‐source relationships

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