The structural, metamorphic and magmatic evolution of Mesoproterozoic orogens

Slagstad, Trond; Viola, Giulio

doi:10.1016/j.precamres.2015.05.031

Cited by 17 publications

(4 citation statements)

References 107 publications

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“…The hiatus of 50 m.yr. between cessation of an orogeny and subsequent generation of A-type granites compares well with the known data from various areas across the world (e.g., Frost et al 2001;Oyhantçabal et al 2007;Bickford et al 2015;Roberts et al 2015). However, the SiO 2 -rich alkali-calcic to calc-alkalic Kanigiri granite with high FeO T is compositionally distinct from the other PAkP plutons, for example, the Elchuru syenite, earlier interpreted as representing rift-related alkaline magmatism.…”

Section: Discussionsupporting

confidence: 76%

New SHRIMP Age and Microstructures from a Deformed A-Type Granite, Kanigiri, Southern India: Constraining the Hiatus between Orogenic Closure and Postorogenic Rifting

Sain

Saha

Joy

et al. 2017

The Journal of Geology

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A new U-Pb zircon SHRIMP age of 1284 Ma from the Kanigiri granite, India, is reported to help constrain the middle to late Mesoproterozoic tectonic evolution of the Nellore schist belt (NSB). The Kanigiri granite has whole-rock chemical characteristics of A-type granites and is marked by light rare earth element enrichment, a strong negative Eu anomaly, and negative Ba, Sr, P, Ti, and Yb anomalies, indicating feldspar, apatite, and ilmenite/magnetite fractionation. Samples show Y/Nb versus Yb/Ta ratios in the range for granites associated with ocean island basalts. This two-mica granite is peraluminous and alkali-calcic to calc-alkalic, and it has high annite to phlogopite proportions (92%-98%). Strong alignment of flattened mafic microgranular enclaves in the granite, together with relatively high-to moderate-temperature crystal plastic deformation fabric in shear zones within the granite, suggest overprinting of subsolidus deformation over a relict magmatic fabric, a feature not very common in true anorogenic granites but reported in late-to postorogenic granites elsewhere. An intrusive relationship with the 1334 Ma Kanigiri ophiolitic mélange, within the NSB, indicates that there is a ≤50 m.yr. gap between the Mesoproterozoic subduction-accretion, represented by the ophiolite mélange and late-to postorogenic granite emplacement. Although the Kanigiri granite occurs in close proximity to mafic and felsic alkaline plutons belonging to the 1250-1400 Ma Prakasam alkaline province (PAkP) in the northern NSB and there is overlap in age, the Atype granitic magma source is apparently unrelated to PAkP alkaline magmatism. Our work further substantiates the observation that A-type granites originate in varied tectonic settings, not necessarily only in a rift-related (intraplate) setting.

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Section: Discussionsupporting

confidence: 76%

New SHRIMP Age and Microstructures from a Deformed A-Type Granite, Kanigiri, Southern India: Constraining the Hiatus between Orogenic Closure and Postorogenic Rifting

Sain

Saha

Joy

et al. 2017

The Journal of Geology

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“…The multiscalar geometric and kinematic complexities of orogen-scale shear zones in Archaean and Palaeoproterozoic shear belts and the evolution of their structural styles through time have attracted geologists' attention hot, old, 'juvenile' crust or other conceptual geo dynamic models must be invoked specifically for this primitive earth (e.g., Hamilton, 2011;Gerya, 2014;Roberts et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A new tectonic model for the Palaeoproterozoic Kautokeino Greenstone Belt, northern Norway, based on high-resolution airborne magnetic data and field structural analysis and implications for mineral potential

Henderson¹,

Viola²,

Nasuti³

2016

NJG

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“…This is not only because of the intrinsic difficulty of geochemically separating rifting within an attenuated continental lithosphere from that in a back-arc (e.g., Pearce, 1996), but also because Early Palaeoproterozoic crust and mantle dynamics, and consequently style of orogenesis, were most likely different from today (e.g., Roberts et al, 2015). In any case, there are other geological aspects of the RTW succession that support a transient compressional tectonic setting during its evolution.…”

Section: Tectonic Setting and Regional Correlationsmentioning

confidence: 99%

Revised structure and stratigraphy of the northwestern Repparfjord Tectonic Window, northern Norway

Torgersen¹,

Viola²,

Sandstad³

2016

NJG

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The Repparfjord Tectonic Window (RTW) consists of a ~8 km-thick low-grade, weakly deformed Early Palaeoproterozoic volcano-sedimentary succession that hosts abundant Cu mineralisations. Two major, sediment-hosted, Cu-deposits occur in the Saltvatnet Group, a <6 km-thick sequence of mainly coarse-grained clastic rocks that forms the core subject of the present study. Results from new mapping, structural analysis and whole-rock geochemistry from the northwestern part of the RTW are presented and used in association with high-resolution geophysical data to propose a revised stratigraphy of the Repparfjord volcano-sedimentary succession and its tectonic and geodynamic settings. The Saltvatnet Group is better characterised as containing four formations, now including also the uppermost volcaniclastic siltstones and dolostone members of the herein newly defined Gorahatjohka Formation. Field oberservations and structural analysis show that the current geometry of the Saltvatnet Group is that of a km-scale, upright, NE-SW-trending anticline, the Ulveryggen anticline, cored by the Saltvatnet Group, which thus represents the lowermost exposed rocks of the RTW. New and existing geochemical data are used to demonstrate that the two volcanic-dominated Nussir and Holmvatnet groups, which crop out on either side of the Ulveryggen anticline, have similar geochemical character and can be interpreted as temporal and lateral correlatives. The basaltic Ulveryggen intrusions within the Saltvatnet Group are geochemically different from any other igneous rocks in the RTW, suggesting that these intruded prior to the volcanic-dominated groups in the RTW. The revised stratigraphy of the RTW is interpreted as reflecting deposition and volcanism in an evolving continental back-arc, which contrasts with the purely intraplate rift setting inferred for most parts of the Fennoscandian Shield in the Early Palaeoproterozoic.

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The structural, metamorphic and magmatic evolution of Mesoproterozoic orogens

Cited by 17 publications

References 107 publications

New SHRIMP Age and Microstructures from a Deformed A-Type Granite, Kanigiri, Southern India: Constraining the Hiatus between Orogenic Closure and Postorogenic Rifting

New SHRIMP Age and Microstructures from a Deformed A-Type Granite, Kanigiri, Southern India: Constraining the Hiatus between Orogenic Closure and Postorogenic Rifting

A new tectonic model for the Palaeoproterozoic Kautokeino Greenstone Belt, northern Norway, based on high-resolution airborne magnetic data and field structural analysis and implications for mineral potential

Revised structure and stratigraphy of the northwestern Repparfjord Tectonic Window, northern Norway

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