The tectonic history of the Tasman Sea: A puzzle with 13 pieces

Abstract

Abstract. We present a new model for the tectonic evolution of the Tasman Sea based on dense satellite altimetry data and a new shipboard data set. We utilized a combined set of revised magnetic anomaly and fracture zone interpretations to calculate relative motions and their uncertainties between the Australian and the Lord Howe Rise plates from 73.6 Ma to 52 Ma when spreading ceased. From chron 31 (67.7 Ma) to chron 29 (64.0 Ma) the model implies transpression between the Chesterfield and the Marion plateaus, followed by strike-slip motion. This transpression may have been responsible for the formation of the Capricorn Basin south of the Marion Plateau. Another major tectonic event took place at chron 27 (61.2 Ma), when a counterclockwise change in spreading direction occurred, contemporaneous with a similar event in the southwest Pacific Ocean. The early opening of the Tasman Sea cannot be modeled by a simple two-plate system because (1) rifting in this basin propagated from south to north in several stages and (2) several rifts failed. We identified 13 continental blocks which acted as microplates between 90 Ma and 64 Ma. Our model is constrained by tectonic lineaments visible in the gravity anomaly grid and interpreted as strike-slip faults, by magnetic anomaly, bathymetry and seismic data, and in case of the South Tasman Rise, by the age and affinity of dredged rocks. By combining all this information we derived finite rotations that describe the dispersal of these tectonic elements during the early opening of the Tasman Sea.

Cenozoic reconstructions of the Australia-New Zealand-South Pacific sector of Antarctica

“…Because the Lord Howe Rise did not originate as a single rigid continental fragment, but instead as many smaller fragments, the opening history of this basin was quite complex [e.g. Gaina et al , 1998]. We have u ed i ochrons and rotations from Gaina et al [ 1998] for our reconstructions (Table 5).…”

“…Gaina et al , 1998]. We have u ed i ochrons and rotations from Gaina et al [ 1998] for our reconstructions (Table 5). Seafloor spreading was only actively occurring in the Tasman Sea in our two oldest reconstructions (Chrons 24 and 27).…”

Evolution of the Louisiade triple junction

“…Our model combines the model for the opening of the Tasman Sea [Gaina et al, 1998] with our finite rotations for the Coral Sea. Rotations constrained by geological and geophysical data but unconstrained by magnetic anomalies were derived using the software PLATES (Table 6) …”

Detrital zircon records of Late Cretaceous syn-rift sedimentary sequences of New Caledonia: An Australian provenance questioned

“…These continental stripes of thinned continental crust now form, in the major part, Zealandia, or preferably, in total, Zealonia (from New Zealand and New Caledonia), a continent-size set of largely submarine highs and plateaus: the Lord Howe Rise, Challenger Plateau, Norfolk Ridge, Campbell Plateau and Chatham Rise (Fig. 1), the emerged parts of which forms present-day New Zealand and New Caledonia (Gaina et al, 1998a(Gaina et al, , 1998bHall, 2002). This view is supported by the many geological features which are shared by New Zealand and New Caledonia, and especially their Mesozoic faunal endemism (Wilckens, 1925;Grant-Mackie et al, 1977;Collignon, 1977;Freneix, 1980Freneix, , 1981.…”