ABSTRACT
The Jaguariaíva Member of Ponta Grossa Formations a Devonian (Praguian/Emsian) unit of Southern America, with essentially shaly lithological nature. It´s shales were formed in marine shelf environment, with organic matter rich intervals. The Jaguariaíva Site is located in the railroad extension Jaguariaíva-Arapoti, inside the urban area of Jaguariaíva. It is characterized by it´s high diversity of invertebrate fossils (Conulariida, Brachiopoda Articulata and Inarticulata, Mollusca Bivalvia and Gastropoda, Tentaculitoidea, Trilobita and Crinoidea), microfossils and abundant ichnofossils of Zoophycus ichnofacies. The invertebrates found are of great paleobiogeographic importance principally because it holds representative elements of the Malvinokaffric fauna.
Keywords: Jaguariaíva, Devonian, Ponta Grossa Formation, Paraná Basin.

INTRODUCTION

    The Devonian of Paraná Basin is represented by the Paraná Group, which comprises Furnas and Ponta Grossa formations. The Ponta Grossa Formation is constituted, bottom to top, by three members: Jaguariaíva, Tibagi and São Domingos (Lange & Petri, 1967). The Jaguariaíva Member is a homogenic package of siltic shales, medium to dark, very fossiliferous and frequently bioturbated. It´s width ranges from 50 to 100 meters in the outcrop bands, values maintained in the subsurface of most cores (Assine, 1996).
    Petri (1948) detailedly studied the section where the paleontological site is found. It is about 100m wide, and it is a fairly representative section of the Jaguariaíva Member, what makes possible the status of type-section of the unit. Many researchers contributed to enlarge the knowledge about the paleontology and stratigraphy of the section (Daemon et al., 1967; Lange, 1967; Lange & Petri, 1967; Popp & Barcellos-Popp, 1986; Melo, 1985; Melo, 1988 and Ciguel, 1989).
    The site is pratically entirely fossiliferous, possessing great paleontological importance due to the occurrence of great diversity of Devonian invertebrate fossils characteristic of the Malvinokaffric fauna, microfossils, plants and abundant ichnofossils.

LOCALIZATION

    The site is located in the railroad extension Jaguariaíva-Arapoti (late Jaguariaíva-Jacarezinho extension), inside the urban area of Jaguariaíva county (latitude 24°14’ S and longitude 49°42’ W), State of Paraná (Figure 1).

Figure 1 - Map of Jaguariaíva Site (modified from Estado do Paraná, 1996).

    After Ciguel (1989) it outcrops between the kilometers 0,5 and 6,2 of the railroad extension, and between 844 and 961 m high. Figure 2 show details of the outcrop.

Figure 2 - Partial view of Jaguariaíva Site (railroad extension Jaguariaíva-Arapoti, km 4,3).

HISTORICAL

    Clarke (1913) studied material collected in the Jaguariaíva area, but not the exact spot of collection. Koslowski (1913) also described some fossils from Jaguariaíva, some of them already studied by Clarke (1913). Oliveira (1927) mentioned that in the Jaguariaíva area the shales outcropped northeast of the town, in the cuts for the railroad to Jacarezinho. Carvalho and collaborators (apud Paiva, 1941) presented a profile of the fossil distribution layers in the Jaguariaíva-Jacarezinho extension.
    Petri (1948) presented a study on the Jaguariaíva Member of Ponta Grossa Formation describing the site detailedly, showing the distribution of fossils found in each level. He registered the following groups: Conulariida, Brachiopoda, Ostracoda, Trilobita, Crinoidea, Bivalvia, Gastropoda and Tentaculitoidea. He evidenced the predominance of Brachiopoda over all other groups and the relative abundance of Trilobita and Mollusca (Bivalvia).
    Sommer (1954) studied the plant remains (Algae) found in the kilometer 5 of the Jaguariaíva-Jacarezinho railroad. Spores obtained close to the fossil indicated the presence of four species of Tasmanites sp. that, according to the author, would not have any relationship with the remains described. Daemon et al. (1967) studied samples collected from four levels and registered the presence of spores that indicated an age correspondent to the top of Early Devonian (Emsian). Melo (1985 and 1988) analyzed the paleobiogeography of the invertebrate fauna of the Jaguariaíva area and it´s relation with Malvinokaffric Realm.
    Several authors have studied the invertebrate fossils with occurrence in the Jaguariaíva area. Among these it may be cited: Mollusca Bivalvia: Morsch (1986) and Kotzian (1995); Mollusca Gastropoda: Kotzian & Marchioro (1997) and Marchioro et al. (1998); Tentaculitoidea: Ciguel (1985); Brachiopoda Inarticulata: Bosetti (1989); Trilobita: Barcelos-Popp (1985); Ostracoda: Pinto & Purper (1986) and Azevedo (1996); Crinoidea: Bolzon & Bogo (1996) and Bolzon & Scheffler (1997); Ichnofossils: Fernandes (1996) and others microfossils: Cruz & Soares (1996) and Grahn (1997).

SITE DESCRIPTION

    Some authors presented a detailed description of the Jaguariaíva Site (Petri, 1948; Popp & Barcellos-Popp, 1986; Ciguel, 1989). The Jaguariaíva Member rests concordantly in contact over Furnas Formation, and is discordantly covered by sandstones of Itararé Group. Petri (1948) maked the vertical stratigraphic profile, totaling 96.8 m wide, what it to be considered the type-section of the Jaguariaíva Member.
    According to Lange & Petri (1967), in the section prevail the shales, frequently micaceous siltstone (Figure 3). At the top are found 20 m of black clayed shales. Siderites and calcareous concretions are common mainly in the middle and top divisions of the section.

Figure 3 -Partial view of site, showing the gray shale and siltstone.

    The marine origin of the Jaguariaíva Member is inferred by the fossil content. The unit was probably deposited in a neritic marine shelf environment (Lange & Petri, 1967). According to Popp & Barcellos-Popp (1986) the fining upward and the change of fauna in the different intervals in the outcrop indicate a transgressive phase in a shallow-water marine environment. By Ciguel (1989), in the section are evidenced gradual changes in the environment with a possible coastline variation. The depositional environment would be located in the coast region to the sublittoral inshore, influenced by the sporadic action of metric-length waves. The bottom of the section would represent an environment comprising the limits between high and low tides.
    Cruz & Soares (1996) found the following association of microfossils: plant cuticles, sporomorphs, Chitinozoa, Acritarca, Tasmanacea and Scolecodonts. By the authors, the palynofacies suggested by the taxa indicates a near coastline deposition.
    The climate during the deposition of sediment in Ponta Grossa Formation has been considerated as cold since Clarke´s work. Diniz (1985) studied core samples and based in the absence of hot climate indications suggested the presence of cold water without glacial influence. Ciguel (1989) based in Tentaculitoidea and because of the absence of specimens of the tropical families of Devonian invertebrates also suggested the existence of cold water.
    Lange (1967) based in Chitinozoa and Daemon et al. (1967) in spores attributed the interval the age of Early Devonian, problably Emsian (D2-A interval). Ciguel 91989), because of Tentaculitoidea suggested an age between Emsian (Zlichovian) and Eifelian, problaby Zlichovian and not only Emsian. Cruz & Soares (1996) based in microfossils suggested Early Devonian age. Grahn (1997) considered the majority of Jaguariaíva´s layers as being Praguian. He commented that in the section a transgressive peak marks the Praguian-Emsian transition. To the author, the Praguian Chitinozoan fauna is named Ramochitina magnifica Lange, 1967 and Hoegisphaera sp. aff. glabra. The D2-A interval (Lange, 1967 and Daemon et al., 1967) was considered of Praguian age by Dino (1999) and Grahn (1999).
    Ciguel (1989) verified that the fossils appear mainly in the shales while the siltstone are often biortubated. The invertebrate fossils appear usually as molds or impressions. The plant vestiges and a few shells and other organic skeletal tissues appear coalified. It was also registered the occurrence of remains of shells of Tentaculitoidea (Ciguel et al., 1987) and Ostracoda (Azevedo, 1996). In some Crinoidea articles occurred substitution by oxides (Bolzon & Bogo, 1996).
    The invertebrate associations present individuals with different completeness classes, depending mostly of the environmental energy and sedimentation rate. Autochtonous and life position fossils occur discordant to the bedding. Principally Conulariidae, Lingulida (Lange & Petri, 1967) and Bivalvia (Kotzian, 1995) occur in life position. Kotzian (1995) observed that most specimens of Bivalvia are found articulated (open or close) and few with shells concordant to the bedding. The Trilobita specimens appear whole, coiled and in different completeness degrees. Brachiopoda Acrotretida are found whole or fragmented.
    Among ichnofossils, Ciguel cited the presence of ichnogenera Planolites sp., Paleophycus sp., Bergaveria sp. and Zoophycus ichnosp. Fernandes (1996) also registered the occurrence of Zoophycus ichnosp. Indet.

PROTECTIVE MEASURES

    The Jaguariaíva Site is placed in the Jaguariaíva-Arapoti railroad extension, inside the urban zone, that coincides with the domains of the railroad. In case the privatization on the railroad takes place, it is mostly important the protection of the area of biggest paleontologic interest by turning them in Environmental Protection Area.

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