Jurassic biostratigraphy and paleoenvironmental evolution of the ...

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30 J.E. Caracuel et al. / Geobios 39 (2006) 25–42
parasequences (2–5 m thick), with stacking of upwardly thicker parasequences. Microfacies range from wackestones to packstones (occasionally crinoidal grainstones) with crinoids, along with thin-shelled bivalves (“filaments”), radiolaria, benthic and planktonic foraminifers, and other macroinvertebrate fragments. Apart from disarticulated crinoid ossicles, benthic macrofauna are almost absent in the Middle Jurassic, in contrast to the Lower Jurassic. Planktonic macrofauna is also scarce, but in the top of some levels, especially toward the upper part, cephalopods proved widespread (ammonites and belemnites). In these levels, better developed in the Malvariche section, ammonites assemblages were collected, enabling recognition of the Lower Bajocian, based on the record of a specimen of Skirroceras sp. Also recognized were the Lower Callovian [Bullatus Zone; based on the record of Homoeoplanulites sp., Macrocephalites sp., and Kheraiceras cf. bullatus (d’Orbigny)], and the Gracilis Zone (Patina Zone sensu Sequeiros, 1974) with abundant and significant ammonites, especially Macrocephalinae and Reineckeidae. No other ammonite faunas were found in the Middle Jurassic. 4.3. Upper Jurassic The Upper Jurassic features at Malvariche and Prat Mayor differ somewhat with regard to lithofacies and faunal assemblages, although the thicknesses are quite similar, 80 and 90 m, respectively (Fig. 2). As a whole, the succession is composed by finely stratified marl and marly limestones which evolved to stratified limestones stacked in thickening upward parasequences (1–2 m thick). Then, massive nodular limestones (sometimes brecciated) alternate with stratified limestones and marls, arranged in upwardly thinning parasequences. Textures and microfacies are highly variable, ranging from pelloidal mudstones to intraclastic packstones (occasionally crinoidal grainstones) with Globuligerina (at the base), filaments, Saccocoma, radiolaria, Globochaete, Stomiosphaera, Cadosina, macroinvertebrate fragments (mainly ammonites and belemnites) and calpionellids (in the upper part). In both sections (Fig. 2), above the multiple Fe–Mn crusts dated as Lower Callovian (Gracilis Zone) outcrops a 5–10 m thick interval of marly limestones and marls, finely stratified, and texturally mudstones to wackestones rich in Globuligerina, attributed to the Callovian?–Oxfordian. In the Malvariche section,7mofslightly nodular marly limestones appear in upwardly thickening parasequences. Towards the top, there is an irregular massive breccioid bank,4mofslightly nodular marly limestones organized in upwardly thinning parasequences, and a characteristic crinoidal bank with an erosive base. Just below this crinoidal bank, ammonite assemblages were collected from the uppermost Kimmeridgian (Beckeri Zone). These slightly nodular marly limestones stacked in Fig. 2. Correlation of the Jurassic sections at Malvariche and Prat Mayor. Fig. 2. Corrélation des sections jurassiques de Malvariche et Prat Mayor. J.E. Caracuel et al. / Geobios 39 (2006) 25–42 upwardly thinning parasequences continues 15 m more over the encrinitic bank, and then change to upwardly thickening parasequences; the facies change gradually to alternating marly/calcareous nodular limestones, often brecciated. The upper 20 m are composed of crinoidal levels and marly intervals with microfacies enriched in hyaline calpionellids which characterized the Upper Tithonian. In the Prat Mayor section above the marly limestones with Globuligerina, outcrop 50 m of ammonitico rosso nodular limestones alternating with thick breccioids banks, organized in upwardly coarsening and thickening parasequences (2–4 m thick). In this interval, ammonite assemblages characterizing the Middle–Upper Oxfordian and the Lower– Middle? Kimmeridgian were collected. In contrast to the Malvariche section, no ammonites from the Upper Kimmeridgian were found. The upper part of section at Prat Mayor appears similar to Malvariche, although more reduced and with characteristic breccioid banks. In both sections, the calpionellids Zones of Chitinoidella, Crassicollaria and Calpionella were recorded. 5. Ammonite biostratigraphy Jurassic ammonite faunas belonging to the Internal Zone of the Betic Cordillera has been rarely and discontinuously reported, and in all cases from the non-metamorphosed Malaguide and “Dorsal” domains (Fallot, 1929, 1931–1934, 1945; Peyre and Peyre, 1960; Azema, 1960, 1961; Paquet, 1969; Geyer and Hinkelbein, 1971, 1974; Seyfried, 1978 and Caracuel et al., 2001). Biostratigraphic data from Sierra Espuña come mainly from Geyer and Hinkelbein (1974); Seyfried (1978) and Caracuel et al. (2001), who described ammonite assemblages belonging to the Domerian, Middle–Upper Toarcian, Upper Bajocian, Oxfordian and Upper Kimmeridgian. For the present paper, more than 500 macroinvertebrates, mainly ammonites, were collected in order to complete and to revise the biostratigraphic framework from the Domerian to the Kimmeridgian in the three previously studied and two new Jurassic sections at Sierra Espuña. The ammonite zonal/subzonal scheme in Cariou and Hantzpergue (1997) for the Mediterranean Domain was used in the Domerian, Toarcian and Callovian stages. Domerian ammonites show good preservation with neomorphosed shells, sometimes ferruginous, and mostly with preserved living chambers; phragmocone septa are consistently preserved (Figs. 4 and 5). There appears to be no taphonomic size bias, although the smaller ammonoids (occasionally fragments) are sometimes found in the interior of Fe–Mn oncoids, with a variable mode of preservation. 31
Page 1 and 2: Abstract Jurassic biostratigraphy a
Page 3 and 4: Perona Unit only outcrops Liassic s
Page 5: to Seyfried (1978); Prat Mayor, Mor
Page 9 and 10: In the lower level of yellowish sil
Page 11 and 12: together with inner molds, sometime
Page 13 and 14: Taramelliceras (Ta.) cf. trachinotu
Page 15 and 16: and tilting). Fig. 3 shows three te
Page 17 and 18: developed within the Middle-Upper J

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