Evolution of the Miocene-Recent Woodlark Rift Basin, SW Pacific, inferred from sediments drilled during Ocean Drilling Program Leg 180

Abstract

The results of drilling during Ocean Drilling Program Leg 180 provide insights into fundamental processes of continental break-up, because rifting can be related to westward propagation of a spreading centre into continental crust. A generally north-south transect of holes was drilled across the Woodlark Rift on the uplifted northern rift margin on the Moresby Seamount (Sites 1114 and 1116), on the hanging wall of the low-angle (25–30°) extensional Moresby Detachment Fault (Sites 1108, 1110–1113 and 1117) and across the downflexed northern rift margin (Sites 1118, 1109 and 1115). The results, when placed in the regional tectonic context, document a history of Palaeogene ophiolite emplacement, followed by Miocene arc-related sedimentation. Regional uplift and emergence of the forearc area took place in Late Miocene time. Submergence to form the Woodlark Rift began in latest Miocene time, marked by widespread marine transgression and shallow-water deposition, accompanied by input of air-fall tephra and volcaniclastic sediments. During Pliocene time, deposition within the rift basin was dominated by deep-water turbidites, including high-density turbidites in the south. Strong extension along the north-dipping Moresby Detachment Fault was active during Pleistocene time, associated with uplift of the Moresby Seamount and shedding of fault-derived talus, mainly of meta-ophiolitic origin. During Pleistocene time, a carbonate platform was constructed to the NW, trapping clastic sediment and resulting in a switch to slower, more pelagic and hemipelagic deposition within the Woodlark Rift Basin. The marked change in rift basin configuration during Pleistocene time may relate to westward propagation of the Woodlark oceanic spreading centre at c. 2 Ma.

Nature of the continent–ocean transition zone along the southern Australian continental margin: a comparison of the Naturaliste Plateau, SW Australia, and the central Great Australian Bight sectors

“…The principal example is off Iberia (Pickup et al 1996;Whitmarsh et al 2001) and its Newfoundland conjugate (Hopper et al 2004). Other examples have been described in the Labrador Sea (Chian & Louden 1994;Chalmers & Pulvertaft 2001), Woodlark Basin (Robertson et al 2001), Great Australian Bight (Sayers et al 2001) and East Antarctica (Colwell et al 2006).…”

Overview of tectonic settings related to the rifting and opening of Mesozoic ocean basins in the Eastern Tethys: Oman, Himalayas and Eastern Mediterranean regions

“…This contrasts strongly with marginal basin settings such as the Woodlark rift basin (e.g. Robertson et al 2001) and the Tyrrhenian Sea (e.g. Marsili Basin: Kastens et al 1988).…”

Late Cenozoic volcanism in the western Woodlark Basin area, SW Pacific: the sources of marine volcanic ash layers based on their elemental and Sr–Nd isotope compositions

“…Furthermore, increasing tectonic activity through time in the area drilled has led to the development of several distinct sedimentary environments (Robertson et al 2001), making correlations between sites less likely. Furthermore, increasing tectonic activity through time in the area drilled has led to the development of several distinct sedimentary environments (Robertson et al 2001), making correlations between sites less likely.…”

“…2). Robertson et al (2001) provide an overview of the sedimentary fill of the western Woodlark Basin. Location and sampling data for each hole are given by Taylor et al (1999b).…”