Early Permian silicified floras from the Perdasdefogu Basin (SE Sardinia): comparison and bio-chronostratigraphic correlation with the floras of the Autun Basin (Massif central, France)

Abstract

International audienceIn the Perdasdefogu Basin (Ogliastra, Sardinia) plants occurring in angular cherts are preserved as siliceous permineralizations. The plant assemblage consists of the genera Sphenophyllum, Arthropitys, Astromyelon, Palaeostachya, Pecopteris, Scolecopteris, Stewartiopteris, Psaronius, Ankyropteris, Anachoropteris; furthermore, probable medullosan wood and ovules, cordaitean stems, leaves and ovules, and Dadoxylon wood have been recorded. Arborescent marratialean ferns are the dominant elements with Pecopteris and Scolecopteris leaves being the most common; the calamiteans are the second in abundance. Generally the chert blocks contain a large number of plant fragments -- roots and leaves are being almost equally represented -- suggestive of a coal ball-like plant accumulation. More rarely a chert block may consist of a single plant part, for example a piece of wood. The preservation and accumulation of the plants are closely comparable to the silicified plant assemblages described from the Lower Permian of Autun and the upper Pennsylvanian of Grand-Croix (Massif central, France) and from the Early Permian Döhlen Basin (Germany). It is certainly significant that the assemblage from the Perdasdefogu Basin is dominated by tree ferns and calamites like the coeval silicified vegetation from Autun. However, like in Autun, the permineralized flora contrasts with the underlying compression floras dominated by conifers and peltasperms. The Perdasdefogu macroflora record suggest a middle-upper Autunian age which corresponds to the Surmoulin and Millery formations of the Autun Basin. This is in agreement with the Asselian-Sakmarian transition as pointed out by the amphibian species found in the same formation, and perfectly correlatable with the same association found in Gottlob-lake (Thuringian Forest Basin). Because of its rich fossil content, the Perdasdefogu Basin represents a reference succession for the Autunian of the entire westernmost palaeo-Tethyan domain and its macrofloral recor

The plant fossil record reflects just two great extinction events

“…(). This group was subsequently adjusted from the primary literature (Rössler and Galtier, ; Hilton et al ., ; Tomescu et al ., ; Kustatscher et al ., , in press; Shi et al ., ; Decombeix et al ., ; Galtier et al ., ; Cariglino et al ., ; Cariglino, ; Wang et al ., ). Gymnosperm data were extracted from Cleal () and Anderson et al .…”

“…Palaeofloristic data about pteridophytes were extracted firstly from Cleal (1993a) and then modified by following Li (1995), Collinson (1996), Cleal and Thomas (1999a) and Taylor et al (2009). This group was subsequently adjusted from the primary literature (R€ ossler and Galtier, 2002;Hilton et al, 2004;Tomescu et al, 2006;Kustatscher et al, 2007, in press;Shi et al, 2010;Decombeix et al, 2011;Galtier et al, 2011;Cariglino et al, 2012;Cariglino, 2013;Wang et al, 2014). Gymnosperm data were extracted from Cleal (1993b) and Anderson et al (2007) with modifications from Cleal and Shute (2003), Uhl (2004), Kustatscher et al (2007), Wang et al (2007), Wang and Pfefferkorn (2010) and Pott (in press).…”

New petrified calamitaleans from the Permian of the Parnaíba Basin, central-north Brazil, part II, and phytogeographic implications for late Paleozoic floras

“…278.4 ± 2.2 (Santos et al, 2006) 0.046512 Springfield (US) 315.2-307.0 (Hilton and Cleal, 2007) 0.055556 Herrin (US) 315.2-307.0 (Hilton and Cleal, 2007) 0.056604 Grand-Croix (Fr) 307.0-298.9 (Galtier, 2008) 0.060241 Mineral-Flemming (US) 315.2-307.0 (Hilton and Cleal, 2007) 0.075472 Calhoun (US) 307.0-298.9 (Hilton and Cleal, 2007) 0.078431 Shangdong (Cn) 298.9-290.1 (Hilton and Cleal, 2007) 0.083333 Shanxi (Cn) 298.9-290.1 (Hilton and Cleal, 2007) 0.085106 Rock Island (US) 315.2-307.0 (Hilton and Cleal, 2007) 0.086957 Duquense (US) 307.0-298.9 (Hilton and Cleal, 2007) 0.086957 Semily Fm. (Cz) 303-7-301 (Martínek and Štolfova, 2009) 0.096774 Sardinia (It) 298.9-290.1 (Galtier et al, 2011) 0.1 Autumn (Fr) 298.9-272.3 (Galtier, 2008) 0.102041 Chemnitz (Gr) 290.6 ± 1.8 (Rößler et al, 2012) 0.108108 Guizhou (Cn) -0.125 Data used in this analysis are shown in the Supplementary data.…”

“…The Jaccard Coefficient is also a very powerful tool for analysing data regarding presence-absence with no importance on abundance (Legendre and Legendre, 1998;Hammer et al, 2001). Thus, cluster and Jaccard Coefficient analyses were undertaken to compare some Moscovian to Cisuralian anatomically preserved floras presented by Hilton and Cleal (2007), augmented by European floras from the Perdasdefogu Basin, Sardinia/Italy (Galtier et al, 2011), Grand-Croix, Saint-Étienne Basin, and Autun/France (Galtier, 2008), Leukersdorf Formation of the Petrified Forest of Chemnitz/Germany , Semily and Vrchlabí formations from Krkonoše Piedmont Basin/Nova Paka/Czech Republic (data provided by Dr. Vaclav Mencl, 2015), and Irati Formation from the Paraná Basin, southern Brazil (Mussa, 1978a(Mussa, ,b, 1982(Mussa, , 1986Mussa et al, 1980;Merlotti, 2009;Merlotti and Kurzawe, 2011). Hilton and Cleal (2007) presented an analysis of 19 Euramerican and Cathaysian floras, ranging from early Bashkirian up to Asselian-Sakmarian age.…”

First tetrapod footprints from the Permian of Sardinia and their palaeontological and stratigraphical significance

“…In Sardinia, the calibration of Late Palaeozoic continental deposits can be based on tetrapod footprints from the Upper Carboniferous San Giorgio Basin (Conti et al, 2004;Fondi, 1980;Marchetti et al, 2018;Nicosia et al, 2004), the Early Permian "branchiosaurs" from the Rio su Luda Fm. in the Perdasdefogu Basin (Ronchi & Tintori, 1997;Werneburg, Ronchi, & Schneider, 2007), and the abundant plant remains described in the Nurra region and other basins of Sardinia (Cassinis et al, 2000;Galtier, Ronchi, & Broutin, 2011;Ronchi et al, 1998;Ronchi, Sarria, & Broutin, 2008). Moreover, radiometric ages were recently provided in the Nurra region for two rhyolitic ignimbrites, namely the Lu Caparoni ignimbrite, whom weighted mean age resulted 297.1 ± 1.8 Ma (middle Asselian), and the Casa Satta ignimbrite, resulted 288.2 ± 2.4 Ma (lower Artinskian; Gaggero et al, 2017).…”