Dunnage Melange and Subduction of the Protacadic Ocean Northeast Newfoundland

Kay, Marshall

doi:10.1130/spe175-p1

Cited by 14 publications

(5 citation statements)

References 29 publications

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“…The common association between accretionary prisms and melange evident in the literature (Cowan, 1974;Dewey & Bird, 1970;Ernst, 1970;Hamilton, 1969;1977;Kay, 1976;Mitchell & Reading, 1971;Moore and Karig, 1980;Moore & Wheeler, 1978;Page, 1970;Storey & Meneilly, 1983;Wood, 1974;Fergusson, 1983; is consistent with the above considerations.…”

Section: Subduction Complex-mclange Associationsupporting

confidence: 76%

The influence of deformation partitioning on dissolution and solution transfer in low‐grade tectonic mélange

Hammond

1987

Journal Metamorphic Geology

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Dissolution of quartz and the recrystallization and re-equilibration of phyllosilicates produce the dark anastomosing seams that dominate microstructures of tectonic mClange which occur in a low-grade, imbricated and multiply deformed, mid-Palaeozoic, intracratonic flysch sequence in northeastern Australia. Seams are composed of very closely spaced or coalesced cleavage lamellae, which are very thin layers of extremely fine-grained phyllosilicates. Cleavage seams enclose lenses of siltstone or greywacke, which formerly occurred in continuous sedimentary layers, indicating extremely heterogeneous and disruptive deformation. Microphacoids enclosed by cleavage seams have subtle shape asymmetries analogous to those of porphyroclasts. Phyllosilicatepreferred orientations within microphacoids commonly lie at a low angle to enclosing seams, and asymmetric relationships occur within seams, The shape and fabric asymmetries appear to be constant, and are regarded as analgous to S and C planes. The number and extent of seams, the amount of dissolution they indicate, and the efficiency of deformation partitioning imply some enhancement of chemical activity and substantial silica loss from the system. This, in turn, suggests the passage of large amount of silica-undersaturated fluid, and mClanges may be zones of high fluid flow. However, the microstructures and the disruptive nature of the fabrics may also reflect the influence of high bulk shear strains and suggest some relationship between the shearing component of deformation and the development of cleavages and foliations.

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Section: Subduction Complex-mclange Associationsupporting

confidence: 76%

The influence of deformation partitioning on dissolution and solution transfer in low‐grade tectonic mélange

Hammond

1987

Journal Metamorphic Geology

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“…Although a sedimentary origin has been attributed to each of these assemblages, their formation implies tectonic instability in the area during deposition. Furthermore, my own observations indicate that, at least in some areas, each of these also exhibit multiple cleavages and overprinting fold structures, indicating local tectonic deformation (for example, Summerford Group exposed along north shore of Summerford Arm, portions of Bid Muddy Cove Group coinciding with Kay's (1976) 'Cobbs Arm Fault Zone'). Following the analogy with the Boones Point Complex, I suggest that these chaotic units were deposited adjacent to tectonic escarpments formed over active thrust faults.…”

Section: Regional Tectonicsmentioning

confidence: 96%

Mélange development in the Boones Point Complex, north-central Newfoundland

Nelson¹

1981

Can. J. Earth Sci.

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The Boones Point Complex in north-central Newfoundland is a narrow mélange belt separating Roberts Arm terrain volcanic and volcaniclastic rocks to the north from Upper Ordovician westerly derived clastic rocks to the south and east. The mélange has a sedimentary matrix and contains a polymict assemblage of blocks. Limestone blocks have yielded Llanvirn–Llandeilo conodont faunas. Sedimentologic and structural analyses indicate that the complex is composed of subaqueous debris flow deposits, which are the proximal facies equivalent of the Late Ordovician clastics to the south. This debris flow material was tectonically deformed prior to the Medial Devonian 'Acadian' orogeny, probably as a result of earlier 'Taconic' thrusting.

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“…Previous field geologists (Harris 1966;Kay 1976) consistently showed faults separating Ordovician and Silurian beds; most of these contacts have turned out to be the margins of olistoliths in olistostromes which were deposited near active faults (Arnott et al 1985). In New World Island, the section along the east coast (adjacent to the Reach Fault) shows a few hundred metres of siltstones and cherts with graptolites (D. clingani zone) followed by a 4.5 km thick formation (Milliners Arm Formation) which shows an upward gradation from fine grained turbidites, through coarse sandy turbidites into mass flow conglomerates.…”

Section: Notre Dame Bay Newfoundlandmentioning

confidence: 99%

Oceans, island arcs and olistostromes: the use of fossils in distinguishing sutures, terranes and environments around the Iapetus Ocean

McKerrow¹,

Cocks

1986

JGS

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The shallow-water benthos of cratonic areas distinguish different continents, and the closure of the Iapetus Ocean during the Ordovician and Silurian can be monitored by the faucas which crossed the ocean at different geological times. Brachiopod and trilobite distributions carry different palaeobiological evidence than, for example, contemporary conodont provinces, which probably reflected a combination of temperature differences and water depths. The Celtic 'Province' is reviewed, and it is concluded that each of the island faunas should be treated separately (since many have links with adjacent continents), rather than together as a province. In Newfoundland, faunas help to locate the site of the main Iapetus closure at the Reach Fault, although a substantial island arc in the Notre Dame Bay area accreted on to America in early Caradoc times. In the late Ordovician and early Silurian of Newfoundland fossils assist in the dating of quite local fault-controlled marginal basins, some of which include large olistostromes; undisturbed assemblages of brachiopods in life position give indications of the depth of water in some basins.

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Dunnage Melange and Subduction of the Protacadic Ocean Northeast Newfoundland

Cited by 14 publications

References 29 publications

The influence of deformation partitioning on dissolution and solution transfer in low‐grade tectonic mélange

The influence of deformation partitioning on dissolution and solution transfer in low‐grade tectonic mélange

Mélange development in the Boones Point Complex, north-central Newfoundland

Oceans, island arcs and olistostromes: the use of fossils in distinguishing sutures, terranes and environments around the Iapetus Ocean

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