Palaeoenvironmental Analysis of the Miocene Barnacle Facies: Case Studies from Europe and South America
Total Page：16
File Type：pdf, Size：1020Kb
GEOLOGICA CARPATHICA, DECEMBER 2018, 69, 6, 573–592 doi: 10.1515/geoca-2018-0034 Palaeoenvironmental analysis of the Miocene barnacle facies: case studies from Europe and South America GIOVANNI COLETTI1, , GIULIA BOSIO1, ALBERTO COLLARETA2, 3, JOHN BUCKERIDGE4, SIRIO CONSANI5 and AKRAM EL KATEB6 1 Dipartimento di Scienze dell’Ambiente e della Terra, Università di Milano-Bicocca, Piazza della Scienza 4, Milano 20126, Italy; [email protected] 2 Dipartimento di Scienze della Terra, Università di Pisa, Via Santa Maria 53, Pisa 56126, Italy 3Museo di Storia Naturale, Università di Pisa, via Roma 79, Calci 56011, Italy 4 Earth & Oceanic Systems Group, RMIT, Melbourne 3001, Australia 5 Dipartimento di Scienze della Terra, dell’Ambiente e della Vita, Università degli Studi di Genova, Corso Europa 26, Genova 16132, Italy 6 Department of Geosciences, University of Fribourg, Chemin du Musée 6, Fribourg 1700, Switzerland (Manuscript received August 1, 2018; accepted in revised form November 28, 2018) Abstract: Acorn barnacles are sessile crustaceans common in shallow-water settings, both in modern oceans and in the Miocene geological record. Barnacle-rich facies occur from polar to equatorial latitudes, generally associated with shallow-water, high-energy, hard substrates. The aim of this work is to investigate this type of facies by analysing, from the palaeontological, sedimentological and petrographical points of view, early Miocene examples from Northern Italy, Southern France and South-western Peru. Our results are then compared with the existing information on both modern and fossil barnacle-rich deposits. The studied facies can be divided into two groups. The first one consists of very shallow, nearshore assemblages where barnacles are associated with an abundant hard-substrate biota (e.g., barnamol). The second one includes a barnacle-coralline algae association, here named “barnalgal” (= barnacle / red algal dominated), related to a deeper setting. The same pattern occurs in the distribution of both fossil and recent barnacle facies. The majority of them are related to very shallow, high-energy, hard-substrate, a setting that represents the environmental optimum for the development of barnacle facies, but exceptions do occur. These atypical facies can be identified through a complete analysis of both the skeletal assemblage and the barnacle association, showing that barnacle palaeontology can be a powerful tool for palaeoenvironmental reconstruction. Keywords: Carbonate Factories, Heterozoan, Barnamol, Barnalgal, Tertiary Piedmont Basin, Sommières Basin, Pisco Basin. Introduction Kočí et al. 2017 are included), but it is only during the Neo- gene that barnacles became really frequent in the shallow- Acorn barnacles (Cirripedia: Sessilia) are common carbonate water environments that they presently master (Darwin 1854; producers in modern and fossil shallow-water shelf environ- Newman et al. 1969; Foster & Buckeridge 1987; Doyle et al. ments (Foster 1987; Foster & Buckeridge 1987; Doyle et al. 1997; Buckeridge 2015). 1997). Albeit often overlooked, this group of sessile, suspen- Worldwide, barnacle facies are particularly well represented sion-feeding crustaceans occur on any available surface in in the sedimentary sequences of the Neogene and the Quater- shallow seas, including “mobile surfaces” like turtles and nary (Sakai 1987; Donovan 1988; Kamp et al 1988; Nebelsick whales (Ross & Newman 1967; Newman & Abbot 1980; 1989, 1992; Hayton et al. 1995; Doyle et al. 1997; Betzler et Scarff 1986; Seilacher 2005; Bianucci et al. 2006; Dominici et al. 2000; Nielsen & Funder 2003; Civitelli & Brandano 2005; al. 2011; Harzhauser et al. 2011; Collareta et al. 2016 a, b). Aguirre et al. 2008; Nomura & Maeda 2008; Radwańska & They are common at middle and high latitudes (Raymond & Radwański 2008; Massari & D’Alessandro 2012; Stanton & Stetson 1932; Hoskin & Nelson 1969; Milliman 1972; Müller Alderson 2013; Brandano et al. 2015; Buckeridge 2015; & Milliman 1973; Farrow et al. 1978; Hottinger 1983; Domack Buckeridge et al. 2018). Based on the ecology of modern taxa, 1988; Nelson et al. 1988; Scoffin 1988; Wilson 1988; Taviani these facies are generally interpreted as shallow-water, et al. 1993; Henrich et al. 1995; Frank et al. 2014; Buckeridge high-energy, deposits. Although this interpretation is usually 2015), but they can also thrive at low-latitudes, especially reasonable, considering the modern distribution of barnacle- in nutrient-rich environments (Glynn & Wellington 1983; rich sediments, barnacle facies clearly display a variability Carannante et al. 1988; Halfar et al. 2006; Westphal et al. that reflects environmental differences. The aim of this work is 2010; Michel et al. 2011; Reijmer et al. 2012; Klicpera et al. to investigate the environmental factors that govern the deve- 2013; Reymond et al. 2016). The fossil record of encrusting lopment of barnacle facies, thus gaining further insights useful cirripedes starts in the Cretaceous (if primitive forms like for palaeoenvironmental reconstructions. To achieve this goal, Archaeochionelasmus Kočí, Newman & Buckeridge, 2017 in four Burdigalian (early Miocene) barnacle facies, from both www.geologicacarpathica.com 574 COLETTI, BOSIO, COLLARETA, BUCKERIDGE, CONSANI and EL KATEB the Northern and Southern hemisphere, were analysed and of the orogenic wedge uplifted the eastern Monferrato and compared by means of palaeontology, sedimentology and resulted in the deposition of the Burdigalian to early Langhian petrography, highlighting their differences and their simila- limestones of the Pietra da Cantoni (Clari et al. 1995; Novaretti rities. The studied barnacle-rich skeletal assemblages are et al. 1995; Maffione et al. 2008). The group is divided into located in the well studied successions of the Pietra da Cantoni two depositional sequences (Bicchi et al. 2006). The oldest Basin in Italy, of the Sommières Basin in France, and of (“Sequence 1” sensu Bicchi et al. 2006) is related to the first the East Pisco Basin in Peru (Fig. 1; Vannucci et al. 1996; and localized marine transgression. The youngest (“Sequence Bicchi et al. 2006; Reynaud & James 2012; Coletti et al. 2015; 2” sensu Bicchi et al. 2006) accumulated at the beginning of Bianucci et al. 2018; DeVries & Jud 2018; Di Celma et al. a transgressive trend in the area that lasted for most of 2018b). Previous research provides a firm basis for the inter- the Miocene. The second sequence is divided into two units. pretation of the barnacle facies of these basins, which has The Lower Unit of Sequence 2 is characterized by coral- received limited attention until now. These facies, despite line-algal-nodule rudstones and floatstones interbedded with having in common abundant remains of barnacles, are charac- grainstones and rudstones rich either in large benthic fora- terized by different skeletal assemblages and different minifera or in barnacles. Deposition occurred during petrographic composition, thus suggesting different palaeoen- the Burdigalian (Novaretti et al. 1995; Ruffini 1995; D’Atri et vironmental settings. The results of this analysis are integrated al. 1999, 2001). The Upper Unit of Sequence 2 is characte- with the existing information on both modern and fossil bar- rized by foraminiferal oozes, testifying hemipelagic sedimen- nacle facies, to provide a general framework for this kind of tation. A bed of condensed sediments, rich in glauconite and sedimentary rock. phosphates, separates the two units (Schüttenhelm 1976; Bicchi et al. 2006). This interval is related to a period of major sediment starvation, caused by the drowning of the carbonate Geological setting factory (Coletti et al. 2015). Both units of Sequence 2 occur in the outcrop of Uviglie (Fig. 1; 45°04’42” N, 08°24’48” E), Pietra da Cantoni Basin, Northern Italy where the barnacle-rich facies has been investigated. The Pietra da Cantoni Group was deposited in the eastern Sommières Basin, Southern France Monferrato, a part of the Tertiary Piedmont Basin that evolved from the late Eocene to the late Miocene, over the inner part of The Alpine Molasse Basin was a seaway during the early the Alpine wedge (Novaretti et al. 1995; Rossi et al. 2009). Miocene; it was about 100 km wide and 1000 km long and During the Aquitanian, the deformation caused by the rotation connected the Western Mediterranean with the Western Fig. 1. Location of the studied facies. A — World map including the location of the studied areas highlighted in the panels. B — Western Europe, magnification of panel B included in panel A. C — Location of the Sommières Basin (France) and of the Pietra da Cantoni Basin (Italy). D — Location of the outcrop of Uviglie (Italy). E — Location of the Boisseron outcrop (France). F — North-western South America, magnification of panel F included in panel A. G — Location of the Ullujaya outcrop (Peru). GEOLOGICA CARPATHICA, 2018, 69, 6, 573–592 MIOCENE BARNACLE FACIES FROM EUROPE AND SOUTH AMERICA 575 Paratethys (Allen et al. 1985; Rögl 1998; Dercourt et al. 2000; that, the Chilcatay Formation has been divided into the Ct1 Reynaud & James 2012). This narrow sea was dominated and Ct2 allomembers (Di Celma et al. 2018b). Ct1 is further by strong tidal currents created by the amplification of subdivided into two facies associations: Ct1a, composed of the Atlantic tide entering the basin from the south-west (Allen sandstones and conglomerates (less common than sandstones) et al. 1985; Harzhauser & Piller 2007). The Sommières Basin alternating with