Lower Ordovician (Arenig) shallow-marine trace fossils of the Pochico Formation, southern Spain: palaeoenvironmental and palaeogeographic implications at the Gondwanan and peri-Gondwanan realm

Abstract

Nineteen ichnospecies belonging to thirteen ichnogenera (Archaeonassa, Catenichnus, Cochlichnus, Cruziana, Didymaulichnus, ?Diplichnites, Gordia, Lingulichnus, Lockeia, cf. Monocraterion, Planolites, Ptychoplasma, and Rusophycus) occur in the Pochico Formation (Arenigian) in the Aldeaquemada section, Sierra Morena, southern Spain, just above the Armorican Quartzite. They belong to the archetypal Cruziana ichnofacies, indicating a lower shoreface-upper offshore zone. The low degree of sediment reworking may be due to a high rate of sedimentation. The trace fossil assemblage, rich in large Cruziana, is typical of the Armorican Quartzite that developed on the margins of Gondwana and peri-Gondwanan microcontinents. The distribution of ichnofauna during the Early Ordovician was partly palaeogeographically controlled, although ichnological data from the literature point to paths of migration between Gondwana, Baltica and Laurentia. Differences between the ichnofauna of Gondwana and Baltica could be conditioned by facies (clastics in Gondwana and carbonates in Baltica) causing a taphonomic filter, because Cruziana requires diversified clastic deposits for preservation. The ichnofauna would also be influenced by trophic group amensalism between filter feeding and deposit feeding fauna, the former prevailing in Baltica and the latter in Gondwana.Keywords: Ichnofossils, Arenigian, clastic sediments, Gondwana, peri-Gondwana, Iberia Resumen Se presenta el análisis sedimentológico/icnológico de los materiales de la Formación Pochico (Arenigian) de la sección de Aldeaquemada, Sierra Morena, Sur de España, provincia de Jaén, justo por encima la Cuarcita Armoricana. Se han reconocido diecinueve icnoespecies pertenecientes a trece icnogéneros (Archaeonassa, Catenichnus, Cochlichnus, Cruziana, Didymaulichnus, ?Diplichnites, Gordia, Lingulichnus, Lockeia, cf. Monocraterion, Planolites, Ptychoplasma, y Rusophycus). Las características icnológicas junto con los rasgos sedimentológicos permiten asignarlas a las icnofacies arquetípicas de Cruziana, comunes de las zonas de shoreface inferior a offshore superior. El grado de bioturbación relativamente bajo puede estar relacionado con una alta tasa de depósito. La asociación registrada, dominada por grandes Cruziana, es típica de la Cuarcita Armoricana desarrollada en los márgenes de Gondwana y peri-Gondwana. La distribucción de icnofósiles del Ordovícico temprano posee, en gran medida, un control paleogeográfico, aunque datos icnológicos procedentes de la literatura indican la existencia de migraciones entre Gondwana, Baltica y Laurentia. Las diferencias entre las asociaciones de Gondwana y Báltica pueden estar asociadas a las diferentes facies, con el dominio de materiales clásticos en Gondwana y de carbonatados en Báltica, causando un filtro tafonómico ya que el potencial de conservación de Cruziana es mucho mayor en las facies clásticas heterolíticas. A estos factores habría que añadir las estrategias de alimentación asociadas, diferenciando entre filtradores y aquellos que...

Deep EndichnialCruzianafrom the Lower-Middle Ordovician of Spain — A Unique Trace Fossil Record of Trilobitomorph Deep Burrowing Behavior

“…M angano and Buatois (2003) treated C. furcifera d 'Orbigny, 1842, C. goldfussi (Rouault, 1850 and C. rugosa d 'Orbigny, 1842, as the subichnospecies of C. rugosa d'Orbigny, 1842, and distinguished them as C. rugosa furcifera, C. rugosa goldfussi and C. rugosa rugosa. However, many other authors retain them at the ichnospecies level (e.g., Aceñolaza and Milana, 2005;Neto de Carvalho, 2006) regarding that all the three ichnotaxa display distinctive morphological features (e.g., Egenhoff et al, 2007) (see discussion in Rodr ıguez-Tovar et al, 2014). There is no doubt that C. rugosa differs from the others ichnospecies of the Cruziana rugosa group by the presence of transverse corrugations (e.g., Seilacher, 1970;Durand, 1985;Fillion and Pickerill, 1990).…”

First discovery of Mississippian trace fossils in the Świebodzice Unit from the Witoszów region (SW Poland)

“…-These trails are in com plete, poorly preserved, so their de ter mi na tion is very dif fi cult. They show some re sem blance to the ichnogenus Didymaulichnus, Young, 1972 (curv ing, smooth bilobate trails with dis tinct me dian fur row, preserved in con vex hyporelief), but dif fers in fea tures such as the lack of thin outer lat eral bev els and of a me an der ing pat tern (Zhu, 1997;Rodríguez-Tovar et al, 2014). Psammichnites was in ter preted as a repichnion of large Pa leo zoic molluscs (Häntzschel, 1975).…”

Large cruzianid trace fossils in the Ordovician of the peri-Baltic area: the case of the Bukówka Formation (Holy Cross Mountains, Poland)

“…Catenichnus contentus Mc Car thy, 1979 is sim i lar but it shows in dis tinct spreite and then dif fers from Arenicolites Salter, 1857. Arenicolites has par al lel limbs and the afore men tioned ichnogenera are char ac ter ized by di ver gent limbs (see Hofmann et al, 2011, Rodríguez-Tovar et al, 2014. A Cambrian trace fos sil of this type with strongly di ver gent arms, de termined as Arenicolites (Stachacz, 2016) may be long to Catenarichnus.…”

“…Quartz sand stone-dom i nated fa cies of the same age as the Bukówka For ma tion are known in peri-Gondwanan ar eas, mostly in the Armori can Quartz ite For ma tion, the fa cies and ichnology of which are well-known from the Ibe rian Pen in sula and France (ref er ences be low). They are rel a tively poorly bioturbated, but they con tain di verse and usu ally well-preserved ichnoassemblages, which in clude at least 35 ichnospecies of 20 ichnogenera de scribed by sev eral au thors (Rouault, 1850;Romano, 1974Romano, , 1991Crimes andMarcos, 1976, Baldwin, 1977a, b;Pickerill et al, 1984;Durand, 1984Durand, , 1985aAceñolaza et al, 2008;Rodríguez-Tovar et al, 2014). An other peri-Gondwanan (Avalonian) unit, i.e.…”

“…For instance, those from the Or do vi cian Sys tem of Gond wana (e.g., ïOrbigny, 1842; Rouault, 1850;Lebesconte, 1883Lebesconte, , 1886Delgado, 1886;Seilacher, 1970;Baldwin, 1977a;Durand, 1984Durand, , 1985aNeto de Carvalho, 2006) are char ac ter ized by an abun dance of large tri lo bite bur rows, which are much rarer in Baltica. At least partly, this could be an ef fect of dif fer ences in fa cies, be cause Gondwanan clastic, usu ally heterolithic sed iments are more suit able for trace fos sil pres er va tion than are the more ho mo ge neous clastic or car bon ate lithologies pre vailing in Baltica (e.g., Rodríguez-Tovar et al, 2014) or an ef fect of in suf fi cient sur vey. In this pa per, a trace fos sil as sem blage includ ing large tri lo bite bur rows is de scribed from the Or do vi cian of the Holy Cross Moun tains in cen tral Po land.…”