Reflections on major North Island basement rock assemblages and on megafaults

Self Cite

Section: Introductionmentioning

confidence: 66%

Section: Kiwitahi Volcanicsmentioning

confidence: 99%

A “least complex” dynamic model for late Cenozoic volcanism in the North Island, New Zealand

Karátson

1994

Self Cite

“…This is a feasible suggestion, because sandstones from the Waioeka petrofacies are petrographically indistinguishable from sandstones of the Manaia Hill Terrane (Fig. 5), and have similar fossil content at this locality (Kear 1993(Kear ,1996Mortimer 1995a). Sedimentation of "western" Torlesse sediments into the Henderson Quarry area (in this case "Manaia Hill basin") was independent from the Waioeka depositional system, since the Waioeka Subterrane was initially not juxtaposed with western terranes (cf.…”

Section: Modelmentioning

confidence: 99%

“…The sediments of Henderson Quarry do not belong to the Waioeka petrofacies but to the Manaia Hill Terrane, as envisaged by Kear (1993Kear ( ,1996; "Awakeri Formation"). This is a feasible suggestion, because sandstones from the Waioeka petrofacies are petrographically indistinguishable from sandstones of the Manaia Hill Terrane (Fig.…”

Section: Modelmentioning

confidence: 99%

Terrane affiliation and terrane boundaries of Mesozoic accretionary complexes, northeastern North Island, New Zealand: Some implications from recycled elastics

Leverenz

Ballance

2001

In the late Mesozoic Waioeka petrofacies in northeastern North Island, New Zealand, sandstone pebbles differ significantly in petrography from their enclosing sandy conglomerate matrix, and yield contrasting provenance signatures. The compositional contrast demonstrates the extrabasinal origin of most of the analysed clasts. Differences in clast provenance have been used to review boundaries and the terrane affiliation to the neighbouring Torlesse and Waipapa composite terranes.A previously postulated Cretaceous large-scale dextral strike-slip displacement of eastern North Island along the Wellington-Mohaka-Whakatane Fault is supported by these data. The timing for this movement can be further bracketed between c. 98 and 85 Ma. The Waioeka and Omaio petrofacies, formerly attributed to the Torlesse terranes as the Waioeka Subterrane, are reinterpreted to constitute a separate terrane (Waioeka-Mata River Terrane). However, the westernmost portion of the former Waioeka Subterrane, west of the Wellington-Mohaka-Whakatane Fault, is considered to be part of the Waipapa composite terrane.

“…Indeed, from east and south of Coromandel Peninsula, potential metamorphosed basement sources reveal increased availability of quartzofeldspathic material of granodioritic bulk composition (Roser & Korsch 1999), as well as a greater variation in abundance of chert and volcanic detritus (Skinner 1978;Kear 1992;Mortimer 1995b).…”

Section: Mesozoic Terrane Sourcesmentioning

confidence: 99%

Provenance and geochemistry of exotic clasts in conglomerates of the Oligocene Torehina Formation, Coromandel Peninsula, New Zealand

Dix¹,

Nelson

2003

Non-marine pebble to cobble conglomerates of the lower Torehina Formation (Oligocene) crop out along western Coromandel Peninsula and overlie, with strong angular discordance, continental-margin metasedimentary rocks (Manaia Hill Group) of Mesozoic (Late Jurassic to ?Early Cretaceous) age. The conglomerates contain provenance information that identifies a pre-Oligocene depositional history obscured by the unconformable juxtaposition of these Tertiary and Mesozoic strata.Most clasts in the lower Torehina Formation are visually similar to local bedrock lithologies, including metamorphosed sandstones and argillites, but are kaolinitic and contain more detrital and authigenic chert, quartz, and potash feldspar. Local derivation of these clasts seems unlikely. By comparing geochemical ratios with those defined for continental margin sandstones, and well characterised New Zealand tectonic terranes, we interpret the majority of clasts in the lower Torehina Formation to have been derived from a dissected orogen, with mixtures of felsic and volcanogenic-derived sediment. The most likely sources are the Waipapa and Torlesse Terranes.The remaining 20-30% of the clasts in the lower Torehina Formation were originally friable, are coarse grained, and appear to be lithologically exotic relative to known metamorphosed sandstones in basement terrane sources on North Island. Some clasts contain coal laminae and particles, and all contain detrital kaolinite as lithic fragments and matrix. Such characteristics imply a non-marine to marginalmarine source containing sediment derived from strongly weathered granite or granodiorite. Mechanical fragility implies a likely proximal, easily erodible source. We propose that this group of clasts was derived from an Upper Cretaceous sedimentary cover, either part of a locally developed basin fill or part of a once regionally extensive cover on North Island. Either case defines a more widely distributed Cretaceous source than found today.