Gravity inversion, AMS and geochronological investigations of syntectonic granitic plutons in the southern part of the Variscan French Massif Central

Joly, Aurore; Faure, Michel; Martelet, Guillaume; Chen, Yan

doi:10.1016/j.jsg.2009.01.004

Cited by 29 publications

(20 citation statements)

References 88 publications

(110 reference statements)

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“…Joly et al, 2009;Charles et al, 2011). In the Yiwulüshan massif, available gravity data from the Chinese regional gravity surveying (1:200,000) have been used to model the bulk crustal scale architecture of the Lüshan pluton and Shishan pluton.…”

Section: Gravity Modelingmentioning

confidence: 99%

“…11B) and two dimensional (2D) gravity modeling has been performed using the Geosoft-GM-SYS software (e.g. Joly et al, 2009;Charles et al, 2011). For this study, average densities were derived from laboratory measurements (Table 2) and the surfaces of deep geometries were constrained by available geological maps and our own field observations.…”

Section: Gravity Modelingmentioning

confidence: 99%

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Late Mesozoic compressional to extensional tectonics in the Yiwulüshan massif, NE China and their bearing on the Yinshan–Yanshan orogenic belt

et al. 2013

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Granitoids play an important role in deciphering both crustal growth and tectonic evolution of Earth. In the eastern end of the Yinshan-Yanshan belt of North China Craton, the Yiwulüshan massif is a typical region that presents the tectonic evolution features of this belt. Our field work on the host rocks has demonstrated two phases of opposite tectonics: compressional and extensional, however, the deformation is almost invisible in the intrusive rocks. To improve the understanding of the tectonic evolution of the Yiwulüshan massif and the Late Mesozoic tectonics of East Asia, a multidisciplinary study has been carried out. In this study, anisotropy of magnetic susceptibility (AMS) and gravity modeling have been applied on these Jurassic plutons (Lüshan, Jishilazi and Guanyindong), which intrude into the Yiwulüshan massif. According to laboratory measurements and microscopic observations on thin sections, the AMS of the Yiwulüshan massif is characterized by secondary fabrics, indicating that the intensive post solidus deformation has reset the (primary) magmatic magnetic fabrics. A relatively gentle NW dipping magnetic foliation has been identified with two distinct groups of magnetic lineations of N34°E and N335°E orientations, namely L M1 and L M2 , relatively. Gravity modeling reveals a southward thinning of the massif with a possible feeding zone rooted in the northern part of the massif. Integrating all results from structural observation, geochronological investigation, AMS measurement and gravity modeling, two tectonic phases have been identified in the Yiwulüshan massif, posterior to the Jurassic (180-160 Ma) magmatism in the Yinshan-Yanshan area. The early one concerns a Late Jurassic-Early Cretaceous (~141 Ma) compressional event with a top-to-the-south to southwest sense of shear. The second one shows an Early Cretaceous (~126 Ma) NW-SE ductile extensional shearing. At that time, sedimentary basins widened and Jurassic plutons started to be deformed under post solidus conditions. In fact, the NW-SE trend of the maximum stretching direction is a general feature of East Asian continent during Late Mesozoic.

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Section: Gravity Modelingmentioning

confidence: 99%

Section: Gravity Modelingmentioning

confidence: 99%

Late Mesozoic compressional to extensional tectonics in the Yiwulüshan massif, NE China and their bearing on the Yinshan–Yanshan orogenic belt

et al. 2013

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“…Besides, AMS is a versatile method for analysing both qualitatively and quantitatively the magmatic and solid-state fabric of granitic rocks (e.g. Hrouda, 1982;Rochette et al, 1992;Borradaile and Henry, 1997;Bouchez, 1997;Talbot et al, 2004;Charles et al, 2009;Joly et al, 2009;Denèle et al, 2011). 708 cores from 78 sample sites have been studied for the Early Cretaceous anatectic granitoids emplaced into the Gudaoling MCC and 403 cores from 50 sample sites have been studied for the two granitic facies of the Early Cretaceous Yinmawanshan pluton (Tables 1 and 2).…”

Section: Anisotropy Of Magnetic Susceptibility Studymentioning

confidence: 99%

Metamorphic Core Complex dynamics and structural development: Field evidences from the Liaodong Peninsula (China, East Asia)

Charles¹,

Gumiaux²,

Augier³

et al. 2012

Tectonophysics

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International audienceMetamorphic Core Complexes (MCC) constitute remarkable features within wide rifts. Based on analogue and numerical modelling, MCC dynamics and structural development are mainly controlled by first geothermal gradient, second the compositional layering, and after the strain rate and partial melting. In the Late Mesozoic, continental extension occurred in East Asia leading to the development of MCC, magmatism and extensional sedimentary basins. Based on an integrated study (i.e. structural and finite strain analysis, petrofabrics, Anisotropy of Magnetic Susceptibility (AMS) and U/Pb on zircon dating), this paper aims at constraining the tectonic evolution and deformation mechanisms in the South Liaodong Peninsula (NE China). The Gudaoling massif is identified as a "migmatitic" MCC developed from Upper Jurassic (ca. 157-154 Ma) to Early Cretaceous (ca. 128-113 Ma). Intrusion of the Yinmawanshan synkinematic pluton (Early Cretaceous) to the south of the dome marks out the final stages of shearing along the Gudaoling detachment zone and of exhumation of the MCC into the upper crust. The Gudaoling MCC and the Yinmawanshan pluton stay in line with the coeval South Liaodong MCC, to the south, all making a ~ 140x30km wide extensional band formed during a regional E-W to NW-SE crustal stretching. The area shows a bi-phased development with a "slow" and a "fast" stage which correspond to (1) crustal necking and (2) dome amplification/exhumation stages according to published thermo-mechanical modelling results. Finally, the Gudaoling MCC lower unit almost exclusively displays migmatites and anatectic granitoids of Late Jurassic and Early Cretaceous, respectively. Occurrence of partial melting during earlier stages of extension seems controlling the initiation of MCC (as a soft anomaly within lower crust). In East Asia, a regional-scale thermal event, during Jurassic-Cretaceous times, may have significantly reduced the bulk lithosphere strength and locally induced partial melting, emphasizing pervasive deformations and development of a wide rift system

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“…As described in the geological outline section, such a time gap is not documented in the French Massif Central, where the Namurian-Westphalian NW-SE extension was followed by the Stephanian-Permian NE-SW extension (Faure and Becq-Giraudon 1993;Faure 1995). If a syntectonic granite had been emplaced in Namurian times, it would probably have recorded the NW-SE stretching associated with the widespread first extensional stage, (Faure 1995;Talbot et al 2005;Joly et al 2009). …”

Section: Regional Correlations Of the Autun And La Serre Faultsmentioning

confidence: 98%

“…In the French Massif Central, one of the main pieces of the Variscan orogen, successive phases of nappe stacking in Devonian and Early Carboniferous times (Burg and Matte 1978;Ledru et al 1989) led to an important thickening of the crust and were followed by an important episode of crustal melting (Duthou et al 1984). During the Late Carboniferous, the collapse of the Variscan Belt (Ménard and Molnar 1989;Burg et al 1994;Faure 1995) generated normal brittle faults (Echtler and Malavieille 1990;Faure and Becq-Giraudon 1993), normal ductile shear zones (Mattauer et al 1988;Malavieille 1987), synkinematic granitoids (Faure and Pons 1991;Talbot et al 2004;Joly et al 2009), and granite-gneiss domes . Although the timing of these events is relatively well established (Faure 1995), the connection between magmatism and extensional tectonics is not always clear.…”

Section: Introductionmentioning

confidence: 99%

Relationships between magmatism and extension along the Autun–La Serre fault system in the Variscan Belt of the eastern French Massif Central

Choulet

Faure

Fabbri

et al. 2011

Int J Earth Sci (Geol Rundsch)

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The ENE-WSW Autun Shear Zone in the northeastern part of the French Massif Central has been interpreted previously as a dextral wrench fault. New field observations and microstructural analyses document a NE-SW stretching lineation that indicates normal dextral motions along this shear zone. Further east, similar structures are observed along the La Serre Shear Zone. In both areas, a strain gradient from leucogranites with a weak preferred orientation to highly sheared mylonites supports a continuous Autun-La Serre fault system. Microstructural observations, and shape and lattice-preferred orientation document high-temperature deformation and magmatic fabrics in the Autun and La Serre granites, whereas low-to intermediate-temperature fabrics characterize the mylonitic granite. Electron microprobe monazite geochronology of the Autun and La Serre granites yields a ca. 320 Ma age for pluton emplacement, while mica 40 Ar-39 Ar datings of the Autun granite yield plateau ages from 305 to 300 Ma. The ca. 300 Ma 40 Ar-39 Ar ages, obtained on micas from Autun and La Serre mylonites, indicate the time of the mylonitization. The ca. 15-Ma time gap between pluton emplacement and deformation along the Autun-La Serre fault system argue against a synkinematic pluton emplacement during late orogenic to postorogenic extension of the Variscan Belt. A ductile to brittle continuum of deformation is observed along the shear zone, with Lower Permian brittle faults controlling the development of sedimentary basins. These results suggest a two-stage Late Carboniferous extension in the northeastern French Massif Central, with regional crustal melting and emplacement of the Autun and La Serre leucogranites around 320 Ma, followed, at 305-295 Ma, by ductile shearing, normal brittle faulting, and subsequent exhumation along the Autun-La Serre transtensional fault system.

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Gravity inversion, AMS and geochronological investigations of syntectonic granitic plutons in the southern part of the Variscan French Massif Central

Cited by 29 publications

References 88 publications

Late Mesozoic compressional to extensional tectonics in the Yiwulüshan massif, NE China and their bearing on the Yinshan–Yanshan orogenic belt

Late Mesozoic compressional to extensional tectonics in the Yiwulüshan massif, NE China and their bearing on the Yinshan–Yanshan orogenic belt

Metamorphic Core Complex dynamics and structural development: Field evidences from the Liaodong Peninsula (China, East Asia)

Relationships between magmatism and extension along the Autun–La Serre fault system in the Variscan Belt of the eastern French Massif Central

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