Early to Middle Miocene Shallow-Water Corals from La Guajira, Colombia
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1 Early to Middle Miocene shallow-water corals from La Guajira, Colombia 2 1,2 2,3 4 3 3 Paola Flórez , Paula Zapata-Ramírez , Carlos Jaramillo , James Klaus 1 4 Departamento de Estratigrafía y Paleontología, Universidad de Granada. 2 5 Corporación Geológica ARES, Bogotá, Colombia. 3 6 Department of Geological Sciences, University of Miami, USA. 4 7 Smithsonian Tropical Research Institute, Panamá, Panamá. 8 9 Corresponding Author: 1,2 10 Paola Flórez 11 Campus Fuentenueva s/n 18002 Granada, España 12 Email address: [email protected] 13 14 15 16 17 18 19 20 PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2507v1 | CC BY 4.0 Open Access | rec: 8 Oct 2016, publ: 8 Oct 2016 21 Abstract 22 23 Here we describe and illustrate 31 Miocene corals species from the Siamaná and Jimol 24 Formations that were collected over two expeditions in the Guajira basin, Colombia during 2011 25 and 2014. Corals include 25 species, derived from 15 different genera and 12 families. Six of 26 them remain with open nomenclature. From the 25 species found in the study area, 88% are 27 extinct and the remaining under endanger status. Most of the species are hermatypic components 28 of the Scleractinian order, with the exception of a member of the Milleporidae family. The corals 29 described are composed of typical taxa from the Oligocene-Miocene transition, during which 30 they were important components in building fringing and patch reefs in the circum- 31 Caribbean/Gulf of Mexico region. The presence of typical Oligocene coral taxa such as 32 Agathiphyllia spp., Antiguastrea sp., and Diploastrea spp. from La Guajira extend the 33 distribution of these genera into the Miocene, adding a more recent geological presence in the 34 Southern Caribbean. Coral assemblages suggest a development in clear, calm and shallow waters, 35 under oligotrophic conditions and only moderate physical disturbance. Our descriptions represent 36 the first effort to characterize the taxonomy of fossilized corals in Colombia. 37 38 Introduction 39 40 Several paleontological works have been conducted to understand the macro-evolutionary 41 patterns of scleractinian corals around the world (Pandolfi, 2011; Pandolfi and Jackson, 2001), 42 and to interpret the environmental conditions that control their growth and distribution (Geister, 43 1977; Jackson et al., 1996; Pandolfi and Jackson, 2006; Novak et al., 2013). Understanding the 44 evolution of scleractinian corals on geological timescales is useful to face the present 45 environmental changes that are driving global extinction of reef-building coral species (Pandolfi, 46 2011). Moreover, coral fossil studies provide exceptional perspective into the long-term 47 maintenance of biological diversity for our future (López-Pérez, 2016). 48 49 Three important events of coral faunal turnover and speciation have occurred over three 50 transitions within the Cenozoic: the Eocene-Oligocene (ca. 34 Ma), the Oligocene-Miocene (ca. 51 23 Ma), and the Pleiocene-Pleistocene (ca. 2.6 Ma) (Budd, 2000). During the second transition PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2507v1 | CC BY 4.0 Open Access | rec: 8 Oct 2016, publ: 8 Oct 2016 52 listed above (from the Oligocene into the Miocene period) the reef building capacity was greatly 53 reduced due to the loss of an estimated 50% of zooxanthellate corals (Edinger and Risk, 1994; 54 1995; Budd, 2000; Johnson et al., 2009; Budd et al., 2011). As a result, several studies have been 55 focused on fossil studies from this interval (e.g. Budd et al., 1994; Johnson, 2007; Johnson et al., 56 2009). These works sought to understand the environmental patterns that control the distribution, 57 presence and demise of these communities in time and space. 58 59 The most representative works started with taxonomical descriptions by Vaughan (1919) and 60 later Frost and Langenheim (1974). Subsequently, more detailed descriptions of the Poritidae, 61 Astrocoeniidae and Faviidae families were provided by Budd (1986, 1987, 1991); Budd and 62 Johnson (1999), and Budd et al. (1992). However, since the paleontological works mentioned 63 above, several changes in the taxonomy and phylogeny of the cnidarians have been revealed, 64 particularly regarding the Scleractinian order (Budd and Stolarski, 2011; Budd et al., 2012) 65 highlighting important phylogenetic implications between the Pacific and the Atlantic faunas 66 (Fukami et al., 2004). 67 68 Several works have contributed paleo-environmental and paleo-oceanographic information and 69 updated the coral taxonomy of different assemblages along the circum-Caribbean/Gulf of Mexico 70 region (e.g. Geister 1975, 1983, 1992; Budd, 1980, 1987, 2000; Budd et al., 1995; 1996, 2011; 71 Johnson, 2001, 2007; Klaus and Budd, 2003; Stemann, 2004; Johnson et al., 2008, 2009 and 72 Klaus et al., 2012). These studies credited tectonic events (Roth et al., 2000; Mutti et al., 2005; 73 Newkirk and Martin, 2009), changes in ocean circulation due to the closing or narrowing of 74 gateways (e.g. the emergence of the Isthmus of Panama) (von der Heydt and Dijkstra, 2005), 75 variations in sea level (Iturralde –Vinent, 2006) as well as temperature (Mutti et al., 2005) as the 76 culprits that drive extinction. 77 78 Although these studies have provided insight into the coral diversity during important peaks of 79 speciation and extinction, few of them have been focused in the Southern Caribbean – Northern 80 South America region (e.g. Johnson et al., 2009), which our research seeks to amend. 81 Consequently, our research focused on new coral collections from Miocene paleo-reefs of the 82 Guajira Basin, bearing fossils of coral species previously thought to be extinct during the PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2507v1 | CC BY 4.0 Open Access | rec: 8 Oct 2016, publ: 8 Oct 2016 83 Oligocene – Miocene transition, therefore giving them a more recent geological record in the 84 Southern Caribbean. 85 86 The purpose is to provide a taxonomical guide that will serve as a baseline for future work on the 87 Cenozoic corals of Colombia. In particular, we studied the taxonomic composition of the corals 88 and provided a description of each one of the species found, along with the occurrences in other 89 regions and their paleo-environmental characteristics. 90 91 Geological setting 92 93 The coral specimens studied were collected in the Cocinetas Basin, from the Siamaná and Jimol 94 Formations in northeast Colombia’s Guajira Peninsula (Fig. 1). Siamaná is a diachronic 95 Formation from Late Oligocene, with unities that reached the Early Miocene (Teatin, 1991; 96 Duque-Caro and Reyes, 1999). The Formation is exposed at the northeastern foothills of the 97 Serranía de Cocinas, the south of the Serranía de Jarara and the west of the Serranía de Macuira 98 (Fig. 1.2). The Early Miocene deposits are characterized by shallow reefal limestones onlapping 99 this paleohighs (Renz, 1960; Rollins, 1965; Lockwood, 1965; Macellari, 1995). Regarding the 100 thickness of Siamaná, it is highly variable ranking from 247 m just north of the Cuiza fault, to 101 over 750 m of lower Oligocene sediments, as pointed out by Duque-Caro and Reyes, (1999). 102 Rollins (1965) measured a thickness of 342 meters near to the Uitpa Formation, which overlying 103 the Siamaná. The contact between the two is discordant, especially around the edges of the basin, 104 but it tends to be transitional in the center (Rollins, 1965). 105 106 The Formation is overlain by the Early Miocene Uitpa Formation, which in turn is overlain by 107 the Middle Miocene Jimol Formation (Moreno et al., 2015). The Uitpa Formation corresponds to 108 a deep marine depositional environment and is composed of silt, selenitic clays and shales, with 109 abundant microfauna (Hendy et al., 2015; Moreno et al., 2015). Fine grained, calcareous 110 sandstone interbeds are common in the lower and upper parts of this formation (Thomas, 1972). 111 Conformably overlying the Uitpa Formation is the Jimol Formation. Jimol is dominated by 112 coarse detritic and calcareous lithologies with fewer interbedded muddy levels (Hendy et al., 113 2015; Moreno et al., 2015) composed mainly of lithic sandstones and mudstones with high PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2507v1 | CC BY 4.0 Open Access | rec: 8 Oct 2016, publ: 8 Oct 2016 114 present of fossiliferous material (Moreno et al., 2015). According to Moreno et al., (2015) the 115 Formation was deposited in a shallow marine environment at the inner shelf depth (< 50m) and 116 contains shallow marine deposits with presence of hermatypic zooxanthellate corals. 117 118 119 120 Figure 1. Study area map with the location of the stations studied. 121 122 Material and Methods 123 124 Coral fossil samples were collected in two expeditions carried out in 2010 and 2014, at five 125 localities of Cocinas Basin: Arroyo Uitpa, Arroyo Ekieps, SW Ekieps, Flor de la Guajira and 126 Punta Espada (Fig. 1, Table 1). Samples were collected manually along 10 m lateral transects, 127 located randomly in the different visited outcrops. In addition, some specimens were obtained 128 outside of lineal transect, in order to increase the taxonomical list as suggested by Johnson and 129 Kirby (2006). The lithology and the stratigraphy of each section as well as the 130 palaeoenvironmental interpretation are presented in Zapata-Ramirez et al. (in prep.). 131 PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2507v1 | CC BY 4.0 Open Access | rec: 8 Oct 2016, publ: 8 Oct 2016 132 The samples were cleaned and brushed with water to remove the sediment. The taxonomic 133 classification were performed following the works of Vaughan (1919); Wells (1956); Frost and 134 Langenheim (1974); Budd (1980; 1986; 1987; 1991), Johnson (2001; 2007); Johnson et al.