Thermal consequences of mantled gneiss dome emplacement

Allen, Tim; Chamberlain, C. Page

doi:10.1016/0012-821x(89)90038-1

Cited by 12 publications

(4 citation statements)

References 15 publications

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“…Intrusive, metamorphic and deformation relationships between the Dassu Gneiss and surrounding rocks are not necessarily the result of dome-stage magma intrusion, as has been suggested (Hanson, 1986;Bertrand et al, 1988). Recent thermal models of mantled gneiss dome structures suggest a possible alternative interpretation (Allen & Chamberlain, 1989). These models have shown that isotherms are domed over such structures, due to a contrast in the thermal conductivities of the dome core and mantle rocks.…”

Section: Metamorphism and Tectonics North Of The Mktmentioning

confidence: 92%

“…These models have shown that isotherms are domed over such structures, due to a contrast in the thermal conductivities of the dome core and mantle rocks. Solid-state emplacement of the dome core rocks by ductile diapiric ascent, due to buoyancy contrast (Fletcher, 1972), advects heat which is further diffusively focused by the conductivity contrast during conductive thermal relaxation (Allen & Chamberlain, 1989). The thermal models predict doming of isograds and possible heating of adjacent gneiss dome structures, such as the Dassu Gneiss, without need for an intrusive heat source (Allen & Chamberlain, 1989).…”

Section: Metamorphism and Tectonics North Of The Mktmentioning

confidence: 99%

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Metamorphic evidence for an inverted crustal section, with constraints on the Main Karakorum Thrust, Baltistan, northern Pakistan

Allen

Chamberlain

1991

Journal Metamorphic Geology

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The Shyok Suture Zone separates rocks in the Asian plate from rocks in the Kohistan-Ladakh island arc.In Baltistan, this suture has been reactivated by the late 'break-back' Main Karakorum Thrust (MKT). The P-T histories of metamorphic rocks both north and south of the MKT have been determined in an effort to place constraints on the tectonic history of this zone. The terranes north and south of the MKT have different, unrelated metamorphic histories. Rocks from the Kohistan-Ladakh island arc south of the MKT have undergone a static low-P (2-4 kbar, c. 500" C) thermal metamorphism. The P-T paths and metamorphic textures of these rocks are consistent with metamorphism due to emplacement of plutonic rocks into the island arc. This metamorphism pre-dates folding and deformation of these rocks. Rocks in the Karakorum Metamorphic Complex, north of the MKT, have experienced a complex deformational and metamorphic history. Prograde metamorphic isograds have been deformed by subsequent southverging folding and by gneiss dome emplacement. However, decompression metamorphic reactions occurred during nappe emplacement. Higher pressure rocks are associated with higher level nappes, creating an inverted pressure metamorphic sequence (8-9-kbar rocks over 5-6-kbar rocks). There is little variation in temperature with structural level (550-625" C). These t\ko different terranes have been juxtaposed after metamorphism by the late south-directed MKT.

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Section: Metamorphism and Tectonics North Of The Mktmentioning

confidence: 92%

Section: Metamorphism and Tectonics North Of The Mktmentioning

confidence: 99%

Metamorphic evidence for an inverted crustal section, with constraints on the Main Karakorum Thrust, Baltistan, northern Pakistan

Allen

Chamberlain

1991

Journal Metamorphic Geology

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“…(6) Heat refraction due to lateral variations in the thermal conductivity of rocks, such as might be consequent on the emplacement of mantled gneiss domes or folding of basement-cover unconformities (e.g. Jaupart & Provost 1985;Allen & Chamberlain 1989;Mildren & Sandiford 1995). (7) Transition from low-T-high-P to high-Tlow-P conditions coincident with the cessation of subduction (e.g.…”

Section: Possible Causes Of High-t-low-p Metamorphismmentioning

confidence: 99%

Ridge-trench interactions and high- T -low- P metamorphism, with particular reference to the Cretaceous evolution of the Japanese Islands

Brown

1998

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A corollary of plate tectonics is that spreading ridges ultimately interact with trenches; this is a consequence of the closure phase of the Wilson cycle that eliminates ocean basins. Ridge-trench interactions generate distinctive igneous, metamorphic, structural and sedimentation effects, which commonly are diachronous parallel to the trench; effects vary with plate boundary geometry and rate of migration is controlled by relative motion vectors. Identification of such interactions in the geological record is uncommon, which suggests that geological events triggered by ridge trench interactions are attributed to other phenomena, such as changes in plate motion or a singularity at the trench. The estimated greater length of plate boundaries in the past means that subduction of a spreading ridge system could have been more common earlier in Earth history.High-T-low-P metamorphism requires a tectonic setting that allows enhanced heat flux, transient advection of heat due to magma ascent, unusually large internally generated heat, or some combination of these features. Subduction of a spreading ridge system produces anomalously high temperatures at shallow crustal depth through the development of a slab window, which allows transfer of sub-slab asthenospheric mantle across the slab to create an enhanced heat flux beneath the overriding plate. This process is important along convergent margins that develop a subduction-accretion complex, and drives low P/T ratio metamorphism and anatexis of the complex. Heat transport occurs by rising magma near the trench, which leads to formation of plutons with characteristic contaminated MORB geochemistry. Near-trench igneous activity and low PIT ratio metamorphism are the most striking features attributable to spreading ridge subduction and slab window formation, and together are likely to be diagnostic of ridge trench interactions.

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“…The distinctive tectono‐stratigraphic characteristic of many granite‐greenstone terrains is a thick, dense supracrustal greenstone assemblage (dominated by mafic‐ultramafic volcanic rocks) overlying a less dense and more evolved granitoid midcrust. Granitoid‐dominated “domes” are usually exposed in the cores of antiformal culminations 30–120 km in diameter, and are separated by comparatively narrow, synclinal greenstone “keels” [e.g., Eskola , 1948; MacGregor , 1951; Anhaeusser et al , 1969; Hickman , 1983, 1984; Allen and Chamberlain , 1989; Marshak et al , 1992, 1997; Choukroune et al , 1995; Collins et al , 1998; Van Kranendonk et al , 2002, 2004]. However, the fragmentary record of the Archean means that our understanding of the primary tectonic mechanisms responsible for early crustal growth and differentiation is incomplete [ Choukroune et al , 1997].…”

Section: Introductionmentioning

confidence: 99%

Conductive incubation and the origin of dome‐and‐keel structure in Archean granite‐greenstone terrains: A model based on the eastern Pilbara Craton, Western Australia

2004

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The Archean East Pilbara Granite‐Greenstone Terrane (EPGGT) of the Pilbara Craton in Western Australia preserves a prolonged record of voluminous mafic‐dominated volcanism and felsic plutonism, commencing at circa 3515 Ma and ultimately resulting in the development of spectacular “dome‐and‐keel” structures. Early crustal growth was dominated by basaltic magmatism and the regional development of a 12–18 km thick greenstone sequence by circa 3335 Ma, overlying widespread 3470–3430 Ma tonalite‐trondhjemite‐granodiorite (TTG) suites emplaced into the middle crust. Stratigraphic and structural relationships imply that voluminous granitoid plutonism and crustal‐scale dome‐and‐keel formation in the southeastern EPGGT was not initiated until circa 3325 Ma but proceeded rapidly over the interval 3325–3308 Ma. This scenario is consistent with a “conductive incubation” period of 10–100 Myr duration, following the burial of radiogenic granitic crust beneath the accumulated greenstone pile. For heat production parameters appropriate to the 3515–3308 Ma EPGGT, we show that the burial of 3470–3430 Ma granitoid‐rich crust beneath the ≥3335 Ma Euro Basalt and its precursors led to long‐term crustal temperature increases of 170–234°C at 35 km depth, with a corresponding reduction in effective viscosity of 2–5 orders of magnitude. In combination with the greenstone‐over‐granitoid density inversion, the changes in effective viscosity of the mid to deep crust due to the burial of heat sources may have provided the crucial trigger for the initiation of dome‐and‐keel formation. Similarly, cooling and strengthening of the crust during syndoming exhumation of the heat production potentially terminated large‐scale dome‐and‐keel amplification.

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Thermal consequences of mantled gneiss dome emplacement

Cited by 12 publications

References 15 publications

Metamorphic evidence for an inverted crustal section, with constraints on the Main Karakorum Thrust, Baltistan, northern Pakistan

Metamorphic evidence for an inverted crustal section, with constraints on the Main Karakorum Thrust, Baltistan, northern Pakistan

Ridge-trench interactions and high- T -low- P metamorphism, with particular reference to the Cretaceous evolution of the Japanese Islands

Conductive incubation and the origin of dome‐and‐keel structure in Archean granite‐greenstone terrains: A model based on the eastern Pilbara Craton, Western Australia

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