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

Abstract

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.

Waipa Supergroup, New Zealand: A proposal

“…Torlesse nomenclature (both lithostratigraphic and tectonostratigraphic) has been applied to them (Speden 1976;Mortimer 1995a). Recent research in the Whakatane-East Cape area (Mortimer 1995a;Kear 2000;Leverenz & Ballance 2001) has confirmed that Triassic Rakaia and Jurassic-Cretaceous Pahau Terranes form the core of the central North Island ranges (Fig. 1); they are composed of quartzofeldspathic greywackes (e.g., Fig.…”

“…5B). In most areas, the Waipa and Pahau rocks are separated from each other by melange, although at Hendersons Quarry quartzose Rakaia or Pahau clasts may be present in Waipa conglomerates (Leverenz & Ballance 2001), and depositional relationships may yet be revealed elsewhere. We also exclude from Waipa Supergroup the younger, more quartz-rich sandstones of the Omaio petrofacies (East Cape; Mortimer 1995a) and Tokatea Hill Formation (Coromandel; Skinner 1972).…”

“…Black (1994) regarded Morrinsville rocks as a "terrane collision facies blanketing zones of imbrication" and Black (1999) regarded Manaia Hill terrane as autochthonous. Leverenz & Ballance (2001) also discussed a number of regional correlations, one possibility being that Waioeka and Manaia Hill rocks are part of the same unit, and that both may have received Murihiku Terrane detritus.…”

“…The high level nomenclature of basement rocks between the Waipa Fault and the North Island Axial Ranges has been the topic of considerable past and ongoing discussion (e.g., Kear 1971;Spörli 1978;Black 1994;Leverenz & Ballance 2001). Irrespective of names, at least two distinct tracts of ground have consistently appeared on geological maps over the decades (Fig.…”

“…Today, most workers usually consider that the entire 10.5 km thickness of the Kawhia-Port Waikato sequence, including the 4.3 km Late Jurassic Apotu and Huriwai Groups, should be regarded as Murihiku Supergroup and as Murihiku Terrane (e.g., Ballance et al 1980;Aita & Grant-Mackie 1992;Ballance & Campbell 1993;Black 1994). Sandstones in the Triassic-Jurassic Kawhia Harbour-Port Waikato area are mainly feldspathic litharenites and lithic feldsarenites with bulk chemical compositions of average andesites and dacites (Ballance et al 1980;Middleton et al 1994;Leverenz & Ballance 2001 ;N. Mortimer unpubl.…”