Contact metamorphism in Middle Ordovician arc rocks (SW Sardinia, Italy): New paleogeographic constraints

Costamagna, Luca Giacomo; Elter, Franco Marco; Gaggero, Laura; Mantovani, Federico

doi:10.1016/j.lithos.2016.09.014

Cited by 10 publications

(8 citation statements)

References 42 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More recently, Costamagna () proposed a new stratigraphic reconstruction for the Bithia Fm and referred it to the Early Cambrian on the basis of the new finding of Archaeocyatha specimens. This interpretation was also supported by the findings of high‐temperature (HT), low pressure (LP) mineral assemblage in marly metasedimentary rocks in the Bithia Fm, related to the emplacement of a Mid‐Ordovician (478–457 Ma) granitic intrusion pre‐dating the Variscan tectonic, metamorphic, and igneous phases (Costamagna, Elter, Gaggero, & Mantovani, ).…”

Section: Introductionmentioning

confidence: 59%

“…Among the three deformation events recognized by Carosi, Perillo, Pertusati, and Gattiglio () and Carosi et al () in the Bithia Fm, the first one, the only pre‐Variscan, has been tentatively referred by Costamagna et al . () to Cadomian Orogeny like the boundary between Bithia and Nebida Fm (now Nebida Group) as proposed by Cocozza since 1979. The key problem in all the attempts to reconstruct the relationships among the formations (or tectonic units) exposed in the Sulcis‐Iglesiente region is given by the striking contrast existing between the dating obtained from fossiliferous content and those obtained from U–Pb zircon geochronology.…”

Section: Discussionmentioning

confidence: 94%

“…Settiballas Micaschist, Bithia Fm, Nebida, Gonnesa, and Iglesias Group. This view has been questioned by the publication of new structural, paleontological, and geochronological data (Costamagna, ; Costamagna et al, ; Pavanetto et al, ). The first controversy regards the geometrical relationship existing between the Bithia Fm and the Early Cambrian Matoppa Fm (i.e., base of the Nebida Group).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, according to Costamagna et al . (), the Bithia Fm is lately intruded by the Ordovician Mt. Filau orthogneiss.…”

Section: Geological Settingmentioning

confidence: 99%

“…(a) Tectono‐metamorphic zones of the Variscan chain of Sardinia (modified from Carmignani et al, ); (b) geological sketch map of south‐western Sardinia (Sulcis area), modified from Costamagna () and Costamagna et al (). Green stars represent the location of samples.…”

Section: Geological Settingmentioning

confidence: 99%

See 4 more Smart Citations

Metavolcanics from Capo Malfatano, SW Sardinia, Italy: New insight on the age and nature of Ordovician volcanism in the Variscan foreland zone

et al. 2017

View full text Add to dashboard Cite

The tectonic/stratigraphic interpretation of the Cambro–Ordovician rocks exposed in the south‐westernmost sectors of the Sardinia island (i.e., belonging to the Bithia Formation or Unit) is still a hot point of discussion. A debated question is also the age of the metavolcanics interbedded in these rocks. In order to provide a clear answer to this problem, in this paper, we provide new U–Pb zircon dating and a petrographic–geochemical comparison of metavolcanics interbedded within the Bithia Formation with similar Sardinian Ordovician calc‐alkaline rocks. The Bithia metavolcanics plot in the rhyodacite/rhyolite field. They show negative troughs for Nb and Ta, negative anomalies for Sr, P, and Ti, and positive peaks for Cs, Rb, K, Th, U, and Pb in the multielement diagram normalized to primitive mantle and significant LREE enrichment, marked negative Eu anomaly, and flat HREE patterns in the chondrite‐normalized REE diagram. Owing to these geochemical features, the Bithia metavolcanics plot in the volcanic arc and active continental margin fields closely resembling Middle‐Late Ordovician felsic metavolcanics from the Sarrabus, Gerrei, Goceano, and Mt. Grighini units. A new U–Pb zircon age of 462.1 ± 4.3 Ma yielded by a metavolcanic layer within the Bithia Formation at Capo Malfatano must be interpreted as the emplacement age. The CL and BSE images of zircon grains do not\ud show any evidence of interaction with late hydrothermal fluids that could have caused Pb loss and rejuvenated ages, confirming the Middle‐Late Ordovician age of the metavolcanics

show abstract

Section: Introductionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 94%