Broken Seamount Fragments in the Setogawa Subduction Complex

Naka, Jiro

doi:10.1007/978-94-009-4720-7_33

Cited by 8 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The samples from the Lully Foothills show significant grouping (Fig. 8), and probably represent a group of closely-related basalt flows from a single seamount (cf . Naka 1985).…”

Section: Tholeiitic Ocean Island Basaltmentioning

confidence: 98%

“…(1) Most have the elemental characteristics of either mid-ocean ridge basalt (MORB) or ocean island basalt (OIB). MORB is interpreted as having formed part of oceanic plates generated at ocean ridges, whereas OIB is interpreted as fragments of seamounts or ocean islands situated on oceanic crust (Thorpe 1978;Lambert et Grapes & Palmer 1984;Jacobi & Wasowski 1985;Naka 1985;Coish et al 1986;Isozaki et MacPherson et al. 1990) . (2) Basalts with a clear volcanic arc trace element character, such as island arc tholeiite (IAT) or calc-alkaline basalt (CAB) are rare, and tend to be confined to melanges formed by submerged arc basement rocks slumping into the trench (e.g.…”

Section: Oceanic Basaltsmentioning

confidence: 99%

See 1 more Smart Citation

Allochthonous oceanic basalts within the Mesozoic accretionary complex of Alexander Island, Antarctica: remnants of proto-Pacific oceanic crust

Doubleday

Leat

Alabaster

et al. 1994

JGS

View full text Add to dashboard Cite

The Mesozoic LeMay Group accretionary complex of Alexander Island, Antarctica, contains thrust-bound slices of accreted ocean floor, ocean islands and seamounts. They represent fragments of proto-Pacific oceanic crust, of which only a tiny remnant (the Phoenix plate) remains off northern Antarctic Peninsula. They therefore provide an excellent opportunity to sample the ancient oceanic crust that formerly occupied the southern Pacific Ocean.All the basalts experienced sea-floor and subduction/accretion metamorphism ranging from zeolite to transitional blueschist facies. On the basis of rare-earth and other immobile trace element characteristics, the basalts are divided into depleted MORB, N-MORB, E-MORB, and tholeiitic and alkaline OIB.Oceanic basalts occur within two rock associations on Alexander Island, basalt-volcaniclastitechert and basalt-volcaniclastite-tuff. The basalt-volcaniclastite-chert rock association is dominated by pillow lavas which have light REE-depleted N-MORB geochemical characteristics, and is interpreted as representing ocean floor formed at spreading centres. Locally, sills of tholeiitic OIB intrude the sequence. The basalt-volcaniclastite-tuff rock association exposed in the Lully Foothills was formed in shallow water during the Early Jurassic. It is geochemically varied, consisting of basalts with N-MORB, E-MORB and tholeiitic OIB characteristics. The association is interpreted to have been formed on a large seamount or ocean island.

show abstract

“…The samples from the Lully Foothills show significant grouping (Fig. 8), and probably represent a group of closely-related basalt flows from a single seamount (cf . Naka 1985).…”

Section: Tholeiitic Ocean Island Basaltmentioning

confidence: 98%

Section: Oceanic Basaltsmentioning

confidence: 99%

Allochthonous oceanic basalts within the Mesozoic accretionary complex of Alexander Island, Antarctica: remnants of proto-Pacific oceanic crust

Doubleday

Leat

Alabaster

et al. 1994

JGS

View full text Add to dashboard Cite

show abstract

“…Depositional juxtaposition through mechanisms such as gravity sliding have been proposed where contacts between the volcanic slivers and adjacent turbidites are locally concordant and interpreted as depositional in origin (e.g., Grapes & Palmer 1984;George 1985;Naka 1985;Roser & Grapes 1990;Sedlock & Isozaki 1990). Recent detailed studies of modern seamounts in trench systems, particularly along the western margin of the Pacific plate, provide important information about the effects of seamount subduction on convergent margin sedimentation and tectonics.…”

Section: Introductionmentioning

confidence: 97%

Radiolarians in offscraped seamount fragments, Aorangi Range, New Zealand

George

1993

New Zealand Journal of Geology and Geophysics

View full text Add to dashboard Cite

Well-preserved radiolarians occur in coloured argillites at two localities in the Torlesse Terrane exposed in the Aorangi Range in the southernmost part of the North Island, New Zealand. The coloured argillites which host the radiolarians are associated with metabasite, and together these rocks are interpreted as remnants of seamounts which were dismembered immediately before or during subduction and accretion. Recent studies have shown that radiolarian faunas are highly useful for dating such oceanic deposits, and for constraining the depositional ages of adjacent turbidites in terranes which are typically sparsely fossiliferous. Radiolarians from the two Aorangi Range localities are consistent with the Late Jurassic to Early Cretaceous age established by regional age constraints, although one genus previously considered to be exclusively Late Cretaceous is also present. This suggests that radiolarian biostratigraphic zones defined by Northern Hemisphere studies should not be rigidly applied to rocks preserved in Southern Hemisphere terranes until radiolarian stratigraphic ranges for these terranes are adequately established.

show abstract

Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica

Doubleday

Tranter

1994

JGS

View full text Add to dashboard Cite

The LeMay Group of Alexander Island, Antarctica, is a Mesozoic accretionary prism that contains slivers of ocean floor and ocean island material, accreted under a range of conditions and depths. It provides a rare opportunity to compare the deformation mechanism paths between oceanic and trench-fill lithologies during subduction and accretion by offscraping or underplating. Ocean floor slivers consist of a bedded basalt–volcaniclastite–chert rock association, overlain by trench-fill sedimentary rocks. The oceanic lithologies initially deformed by cataclasis, combined with particulate flow in the volcaniclastic rocks. At shallow levels the clastic trench-fill sedimentary rocks deformed by independent particulate flow, which changed to cataclastic flow at depth. At those depths crystal plasticity affected the cherts and jaspers. At the deepest levels achieved in the subduction zone, crystal plasticity was the dominant deformation mechanism in the clastic sedimentary rocks, whilst cataclasis continued in the lavas. Deformation was synchronous with metamorphism up to transitional greenschist–blueschist facies. All lithologies were affected by pressure solution after accretion, with the formation of a bedding-parallel or sub-parallel cleavage. The deformation mechanism paths indicate that (1) there is a crystal plastic deformation field at deep levels in the subduction zone, and (2) that the base of the pressure solution field is concordant with the decollement. A frontally accreted ocean island is exposed in the Lully Foothills, and consists of a basalt–volcaniclastite–tuff rock association. Deformation is represented only by a patchily distributed bedding-sub-parallel pressure solution cleavage in the tuffs and volcaniclastites, and is probably related to loading. Metamorphism does not exceed prehnite–pumpellyite facies. The accreted ocean island indicates that such features can be incorporated into accretionary prisms at shallow levels without significant segmentation.

show abstract

Broken Seamount Fragments in the Setogawa Subduction Complex

Cited by 8 publications

References 20 publications

Allochthonous oceanic basalts within the Mesozoic accretionary complex of Alexander Island, Antarctica: remnants of proto-Pacific oceanic crust

Allochthonous oceanic basalts within the Mesozoic accretionary complex of Alexander Island, Antarctica: remnants of proto-Pacific oceanic crust

Radiolarians in offscraped seamount fragments, Aorangi Range, New Zealand

Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica

Contact Info

Product

Resources

About