Structure and tectonic setting of the SE Sardinia mafic dyke swarm. Insights for the stress state during magma emplacement in the upper crust

Martínez-Poza, Ana Isabel; Druguet, Elena

doi:10.1016/j.jog.2016.05.012

Cited by 17 publications

(5 citation statements)

References 74 publications

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“…Moreover, the observed peperite‐like dikes (Figure 3j) may be interpreted as preserved fluid‐filled cavity tips of propagating apophysis (Poppe et al., 2020 and references therein) where localized magma‐water interactions occurred (Westerman et al., 2017). Blunt geometries of some tips, irregular contacts, the larger thickness of the dike toward the tips, as well as plastic deformation of the low‐rigidity material indicate a shear‐dominated deformation (Mode II), as similarly observed in the literature (Dering et al., 2019; Martinez‐Poza & Druguet, 2016). This is the case where the host rock consists of cataclastic limestones, like in the uppermost part of the outcrop (Figure 4).…”

Section: Discussionsupporting

confidence: 75%

The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

Natale,

Vitale,

Giordano

et al. 2023

Geochem Geophys Geosyst

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The Roccamonfina volcano is located within the Garigliano Graben (southern Apennines, Italy) and has been active throughout the Middle‐Late Pleistocene. Along its polyphase volcanic history (630–55 ka), including several caldera‐forming eruptions (385–230 ka), several effusive/mildly explosive monogenetic events occurred along the volcano slopes, within the summit caldera, and along the graben‐bounding carbonate reliefs. In this paper, we present a multidisciplinary study of a mafic magmatic feeder dike intruded within the Meso‐Tertiary carbonates and overlying Lower Pleistocene breccias of Mt Cesima, northeast of the Roccamonfina volcano. We performed a stratigraphic and structural survey of the area and petrographic analyses on several samples of the dike. Results indicate that a ∼1 km long fissure fed an eruption that also emplaced a Strombolian pyroclastic sequence. Petrological data show that an open‐system mafic recharge fueled the tephritic magma that fed the eruption, whereas no evidence of significant pre/syn‐eruptive assimilation of carbonate has been identified. Stratigraphic and petrological data do not allow to firmly constrain the timing of the eruption, which could belong both to the pre‐Brown Leucitic Tuff (>354 ka) and to the post‐White Trachytic Tuffs (<230 ka) epochs of activity of the Roccamonfina volcano. Structural data show that the dike is broadly oriented E‐W and changes direction toward NE‐SW in correspondence with a pre‐existing fault damage zone. We suggest that magma was intruded during an N‐S trending extensional event in the Middle Pleistocene, whose prolonged activity resulted in regional uplift and exhumation of regional significance.

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Section: Discussionsupporting

confidence: 75%

The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

Natale,

Vitale,

Giordano

et al. 2023

Geochem Geophys Geosyst

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“…The co‐occurrence of mechanical features predicted by both end‐member modes is called “mixed‐mode” fracturing (Rubin, 1995) and was found both in natural outcrops (e.g., Dering, Micklethwaite, Cruden, et al, 2019; Martinez‐Poza & Druguet, 2016) and laboratory experiments of fluid intrusion in natural rock samples (e.g., Zheng et al, 2019). Mechanical indicators of LEFM, such as tapered intrusion fronts and cavities, were found in some cases in association with dike opening profiles that depart from the parabolic shape expected in elastic materials (Daniels et al, 2012; Vachon & Hieronymus, 2017) and blunt intrusion tips and shear‐mode fractures.…”

Section: Magma Emplacement Modelsmentioning

confidence: 99%

Structural and Geochemical Interactions Between Magma and Sedimentary Host Rock: The Hovedøya Case, Oslo Rift, Norway

Poppe

Galland

Winter

et al. 2020

Geochem Geophys Geosyst

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Two end‐member conceptual models are used to describe deformation of the Earth's crust induced by magma intrusion. “Mode I” fracturing assumes tensile or opening‐mode, elastic deformation, while “Mode II” fracturing assumes plastic shear‐mode deformation around a viscous indenter. Field observations of both mechanisms exist, but it remains unclear which mechanism dominates in which conditions. We describe intrusion geometries, host rock deformation, and geochemical magma‐host rock interactions around 53 exceptionally preserved, tephrite‐basanite Permian dike segments of 0.5‐ to 30‐cm thickness. These thin dikes, that is, “dikelets,” intruded Late‐Ordovician carbonate‐rich sedimentary rocks on Hovedøya island, Oslo Rift, Norway. Dikelets emplaced in preexisting fractures dominantly created cavities ahead of their narrow, tapering tips and are associated with bent host rock, broken bridges, and stepped segmented geometries. Other tips are blunt with dense brittle fracturing around them. Also, cross‐sectional intrusion segment opening profiles deviate from parabola‐shaped profiles typical for elastic media. The observations demonstrate that dominant opening‐mode host rock deformation can coexist with shear‐mode deformation locally. Alignment of most dikelet segments along the dominant host rock fracture directions highlights the control of local structural orientations on magma emplacement. Analysis of bulk major and trace element compositions, in situ micro‐XRF sample analysis and carbon and oxygen stable isotope compositions, suggests that thermochemical interactions between magma and the carbonate‐rich host rock produced a low‐viscosity mixture of magma, pore water, and gas. We propose that such low‐viscosity hybrid fluid may assist in the intrusion of magma in sedimentary rocks by filling the cavity ahead of propagating sheet intrusion tips.

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“…Variations in strike and/or dip have also been observed along individual dykes, revealing a continuous zigzagging stepped geometry (Fig. 3a, c, e, g–i) and are probably equally related to the exploitation of joints (Martinez-Poza & Druguet, 2016). The joints/faults within the host granitic rocks and surrounding Upper Carboniferous strata were generated in an extensional regime in Late Carboniferous.…”

Section: Discussionmentioning

confidence: 88%

“…Thus, these joints/fractures could be deemed as the 'contemporaneous' products with dykes in central West Junggar. A plausible model is that 'contemporaneous' joints in the granitoids were exploited during dyke emplacement and subsequently reactivated during cooling and post-cooling events, implying active tectonics during and after the intrusion of the dyke swarm (Martinez-Poza & Druguet, 2016).…”

Section: D2 Emplacement Of Dykesmentioning

confidence: 99%

Subducted oceanic slab break-off in a post-collisional setting: Constraints from petrogenesis of Late Carboniferous dykes in central West Junggar, Xinjiang, NW China

Gao,

Li,

Kerr

et al. 2023

Geol. Mag.

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Numerous Late Carboniferous – Early Permian dykes are found in West Junggar and represent an important part of the Central Asian Orogenic Belt. In this contribution, we use these dykes to assess the tectonic regime and stress state in the Late Carboniferous – Early Permian. The West Junggar dykes are mainly diorite/dioritic porphyrite with minor diabase and were formed in 324–310 Ma. They have been divided into two groups based on their orientation, petrology and geochronology. Group 1 dykes mostly comprise WNW-striking dioritic porphyrite and NE-striking diorite with minor diabase and resemble the Karamay-Baogutu sanukitoid. They were probably formed from depleted mantle at a relatively high temperature and pressure with the addition of 1–2% sediment/sedimental partial melt and 0–5% trapped oceanic crust-derived melts. Group 2 dykes are ENE-striking and are similar to sanukite in the Setouchi Volcanic Belt. These dykes were also derived from depleted mantle at a shallow depth but high temperature with the addition of 2–3.5% sediment/sedimental partial melt. Magma banding and injection folds in dykes and host granitoids indicate magma flow. Paleostress analysis reveals that both groups of dykes were formed in a tensile stress field. Their emplacement is favoured by presence of pre-existing joints or fractures in the host granitoids and strata. We conclude that large-scale asthenosphere mantle upwelling induced by trapped oceanic slab-off can explain the magmatism and significant continental crustal growth of West Junggar during Late Carboniferous to Early Permian.

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Structure and tectonic setting of the SE Sardinia mafic dyke swarm. Insights for the stress state during magma emplacement in the upper crust

Cited by 17 publications

References 74 publications

The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

Structural and Geochemical Interactions Between Magma and Sedimentary Host Rock: The Hovedøya Case, Oslo Rift, Norway

Subducted oceanic slab break-off in a post-collisional setting: Constraints from petrogenesis of Late Carboniferous dykes in central West Junggar, Xinjiang, NW China

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