Introduction and Explanatory Notes, Leg 81, Deep Sea Drilling Project

Roberts, D.G.; Backman, Jan; Morton, Andrew; Keene, J. B.

doi:10.2973/dsdp.proc.81.101.1984

Cited by 5 publications

(5 citation statements)

References 5 publications

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“…3) was due not only to slightly higher ocean-crust production but also to a late Paleocene-early Eocene tectonic reorganization. The largest change in ridge length of the past 100 My occurred È60 to 50 Ma (57), associated with the opening of the Norwegian-Greenland Sea, a significant global reorganization of spreading ridges, and extrusion of 1 to 2 Â 10 6 km 3 of basalts of the Brito-Arctic province (58). A late Paleocene to early Eocene sealevel rise coincides with this ridge-length increase, suggesting a causal relation.…”

Section: Relation Of Sea Level To Evolution and Climate Changesmentioning

confidence: 99%

The Phanerozoic Record of Global Sea-Level Change

Miller

Kominz

Browning

et al. 2005

Science

2,781

2,328

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We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 +/- 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10(4)- to 10(6)-year scale, but a link between oxygen isotope and sea level on the 10(7)-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).

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Section: Relation Of Sea Level To Evolution and Climate Changesmentioning

confidence: 99%

The Phanerozoic Record of Global Sea-Level Change

Miller

Kominz

Browning

et al. 2005

Science

2,781

2,328

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“…Seaward‐dipping reflectors (SDRs) are found on all volcanic passive margins and associated with the transition from continental rifting to full lithospheric separation and seafloor spreading (e.g., Menzies et al, ; White & McKenzie, ). They were first discovered in the late 1970s and studied extensively in the 1980s by marine seismic reflection surveys and through the Ocean Drilling Programme (Eldholm et al, ; Hinz, ; Mutter et al, ; Roberts et al, ). SDRs are thick packages of high‐amplitude reflectors, which diverge and increase in dip toward the ocean (Hinz, ).…”

Section: Introductionmentioning

confidence: 99%

“…They form packages that are commonly less than 10‐km thick, but they can exceptionally reach thicknesses of 20 km (e.g., Berndt et al, ; Stica et al, ) with much variation both along, and between, margins. The results of the Ocean Drilling Programme (ODP) in the North Atlantic, and specifically on the Edoras and Hatton Banks of the Rockall Basin, the Vøring margin of Norway and Eastern Greenland, has shown that SDRs consist of subaerial, tholeiitic lavas interbedded with volcaniclastic sediment, volcanic tuff, and hyaloclastite (Eldholm et al, , ; Larsen et al, ; Roberts et al, ). An understanding of how SDRs form is important for fundamental questions such as the process of continental breakup and ocean basin formation, and the nature of the continent ‐ocean boundary on volcanic margins.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Seaward‐Dipping Reflectors Along the South American Atlantic Margin and Implications for Continental Breakup

et al. 2018

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Thick packages of lavas forming seaward‐dipping reflectors (SDRs) are diagnostic features of volcanic passive margins. Despite their significance to continental breakup studies, their formation mechanism is still debated. We use ~22,000 km of high‐quality, depth‐migrated, seismic data to document the three‐dimensional geometry of SDRs offshore South America. We find two types: Type I are planar and occur as fault‐bounded wedges. Type II are characterized by reflections that become more convex‐upward in the downdip direction and terminate against a subhorizontal base. We interpret the transition from Type I to Type II SDRs to represent a continuum from continental rifting to full plate separation with formation of new, subaerially generated, magmatic crust. Type I SDRs formed in half grabens during the stretching of continental crust, while Type II lavas infill the space produced by flexing of the crust due to the solidification of the underlying feeder dikes as the magmatic crust moved away from the spreading center. Type II SDRs vary in length and thickness along the margin. In the north, close to the Paraná flood basalts, they are long (tens of kilometers), reach thicknesses of up to 15 km, and have an across margin width of up to 600 km. To the south the Type II SDRs are thinner with lava lengths of <10 km. We propose that Type II lavas in the north erupted from a subaerial, plate spreading center above the Tristan mantle plume and that the shorter lava flows to the south indicates eruption into water, consistent with a cooler, off‐plume mantle.

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“…For volcanic margins, seaward‐dipping reflectors (SDRs) show distinct synrift features accumulating on transitional crust during breakup (Menzies et al, 2002; Roberts et al, 1984; Sager et al, 2013). For convenience, we use the terms troughward‐dipping reflectors and ridgeward‐dipping reflectors to describe the reflectors dipping to the Sorol Trough and the opposite, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…For volcanic margins, seaward-dipping reflectors (SDRs) show distinct synrift features accumulating on transitional crust during breakup (Menzies et al, 2002;Roberts et al, 1984;Sager et al, 2013). oceanic plateau; however, they still remain controversial.…”

Section: Intrabasement Reflectors Related To Extrusive Centresmentioning

confidence: 99%

Construction of the Caroline Ridge uppermost basement in the West Pacific: Implications from intrabasement seismic reflectors

Zhang,

Dong,

et al. 2023

Geological Journal

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The construction model of the Caroline Ridge uppermost basement is still unresolved, requiring more inference from limited geophysical observational data. Here, we systematically reveal intrabasement seismic reflectors of volcanic sequences within the rifted and subsidence domains of the Caroline Ridge. Extrusive centres and three types of intrabasement reflectors, that is, relatively horizontal, ridgeward‐dipping and folded reflectors, have been identified. Extrusive centres in the rifted domain are characterized by domal shapes and produce sub‐parallel stratified intrabasement reflectors within the conduits that connect with the relatively horizontal reflectors distributed on both sides of the basement highs. Intrabasement reflectors display increasing dip angles away from the extrusive centre and present ridgeward‐dipping reflectors but not troughward‐dipping reflectors in subsidence domain 1, suggesting a brittle deformation process. Layered intrabasement reflectors are developed within subsidence domain 2 but display folded and mounded morphologies, suggesting a ductile deformation process. We propose that the Caroline Ridge formation was supported by discrete extrusive centres, and the uppermost basement construction model has experienced stages of transition from brittle deformation to ductile deformation, which can provide new clues for the early‐stage crustal evolution of global oceanic plateaus.

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Introduction and Explanatory Notes, Leg 81, Deep Sea Drilling Project

Cited by 5 publications

References 5 publications

The Phanerozoic Record of Global Sea-Level Change

The Phanerozoic Record of Global Sea-Level Change

Characterization of Seaward‐Dipping Reflectors Along the South American Atlantic Margin and Implications for Continental Breakup

Construction of the Caroline Ridge uppermost basement in the West Pacific: Implications from intrabasement seismic reflectors

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