Paleomagnetism, K-Ar dating and tectonic interpretation of Upper Cretaceous and Cenozoic volcanic rocks of the Chatham Islands, New Zealand

Abstract

New K·Ar age determinations on basaltic volcanic sequences in the Chatham Islands, 900 km east of South Island, New Zealand, combined with additional field and paleontologic studies, have led to a stratigraphic revision and the recognition of three distinct volcanic episodes-Late Cretaceous (70-85 m.y.), Eocene-early Oligocene (35-53 m.y.), and late Miocene-Pliocene (2-6 m.y.). Paleontology, palynology, and

The Raukumara paleomagnetic domain: Constraints on the tectonic rotation of the East Coast, North Island, New Zealand, from paleomagnetic data

“…We refer to these two regions as the Raukumara Domain in the northeast and the Wairoa Domain in the southwest. When referenced to the Pacific plate, for which Cenozoic paleomagnetic pole positions show no apparent polar wander (Grindley et al 1977), the Raukumara Domain has rotated at about the same rate as the Australian plate, implyi~g no differential or tectonic rotation, whereas the Wairoa Domain has rotated some 50° in the last 10 Ma (Wright & Walcott 1986). …”

Are the Pacific and Indo–Atlantic hotspots fixed? Testing the plate circuit through Antarctica

“…To address this issue, we compare paleomagnetic poles from the Pacific plate with non-Pacific mean poles of Besse and Courtillot [18] and DiVenere et al [15] We also note that the Late Cretaceous paleomagnetic pole from the Chatham Islands off New Zealand (NZ 75), which was based on paleomagnetic laboratory analysis of 84 samples collected from 29 sites in volcanic rocks [19], lies comfortably with the other Pacific poles of similar age. The Chatham Island pole falls within the estimated error ellipses of both the 76 Ma skewness-based (Pac 76v) and seamount-based (Pac 76s) poles and is therefore not statistically distinct from these.…”

“…Paleomagnetic poles have also been derived from the skewness of marine magnetic anomalies on the Pacific plate [20,[24][25][26][27]. [18] global, non-Pacific, synthetic APW path transferred to Antarctica [15] and to the Pacific using Cande et al [8]; NZ 75, [19] ca. 75 Ma result from Chatham Islands, south Pacific; Pac 32 through Pac 76v are Pacific anomaly skewness poles; Pac 32, [20]; Pac 57, [26]; Pac 65, [24]; Pac 73, [25]; Pac 76v, [27]; Pac 76s, [23] Pacific seamount-based pole; Pac 81, co-latitude circle from Detroit Seamount [47].…”

Basement structure at the Chatham Islands

“…An onshore refraction survey near Te Whanga Lagoon (CI/3; Wood and Ingham, 1981) Zealand, Volume 19, 1989 Neogene in age, similar to those seen in the vicinity of Pitt Island (Grindley et al, 1977).…”

“…The basin is poorly defined on the seismic data, but the dips of the reflectors suggest that the graben-fill sediments have been disrupted by later volcanism or tectonism. The northern portion of Chatham Island is dotted with small Eocene-Oligocene volcanoes (Northern Volcanics; Grindley et al, 1977;Fig. 2).…”