The Tatuí Formation (Early Permian, Paraná Basin), Brazil: Paleontology and Paleoenvironmental Considerations

São Paulo, southeast Brazil. It is studied herein, through outcrops at the eastern border of the basin, which are siltstones and fine sandstones, interbedded with some coarse and conglomeratic sandstones. Published papers on its fossils are sparse, dealing with some groups but not involving the entire association. This paper deals with ichnofossils, arthropods (conchostracans, isopods, and indeterminate crustaceans), plants (pteridophytes and spermatophytes) and fish remains (scales and teeth of Actinopterygii and Sarcopterygii). Foraminifers and sponge spicules were reported in short communications without illustrations and from uncertain stratigraphic positions. The Tatuí Formation paleoenvironmental deposition evolved through three phases. The first contains only the euryhaline fossils in siltstone beds. The second phase is regressive, with continental fossils (conchostracans and plants) in massive or laminated siltstone beds and conglomerates. The third stage is transgressive with hummocky cross – stratification in sandstone and increasing salinity.


INTRODUCTION
Pennsylvanian -Permian lithostratigraphic units of the Brazilian Paraná Basin are, from the oldest to the youngest: Itararé, Guatá, and the Passa Dois Groups.They are joined in the Gondwana I Supersequence by Milani and Ramos (1998).
The Early Permian Tatuí Formation, studied in this contribution, is chrono-correlated with two formations of the Guatá Group, Rio Bonito, and Palermo, from southern Brazil, and from South Africa, Prince Albert Formation (Milani et al., 2007;Holz et al., 2010;Chahud, 2011).
All known fossiliferous outcrops of the Tatuí Formation are located in the uppermost 10m of the unit (Mezzalira 2000;Chahud, 2011;Chahud et al., 2010a;Chahud et al., 2012).The present contribution stands out from previous investigations by different approaches as to details of fossil taxa, granulometry, depositional evolution, biostratigraphy and paleoenvironments.

TATUÍ LITHOSTRATIGRAPHY
Older researchers considered this formation as essentially made up of two lithologic bodies, recognized by different colors, with a diastem between (Soares, 1972, Fulfaro et al., 1984).
The second body is gray-greenish to yellow-greenish siltstones and fine sandstones and conglomerates exhibiting rather round clasts with crossbedding and ripple marks.From angular to rounded chert pebbles are reported.Three lithologies are reported, correlated with the classical lithologic bodies.
The herein described lithologies are the only surely fossiliferous Tatuí beds.They are the following:

Fine to very fine sandstones with hummocky
These sandstones are well sorted, yellow whitish or greenish, sometimes bearing dots and blots.They mostly lie right under the Irati Formation beds.The outcrops are centimeters to two meters thick, the hummocky cross -beds may reach 0.5m high.Chahud (2007) reported small parallel ripple marks apparently symmetric, striking N20E, less than 0.5cm high, on upper beds of this facies.
Very fine, thinly laminated or massive whitish sandstones, outcrop right under an Irati Formation bed.Sometimes these sandstones acquired a light yellow color, possibly due to weathered pyrite nodules, from the basal Irati bed.
This facies is interbedded with other Tatuí lithologies, discussed below.It is scarcely fossiliferous, small Osteichthyes scales (Ragonha, 1978;Chahud and Petri, 2008a, 2008b, 2009b, 2010b, 2012a, 2012b, 2014) are rarely present.Ichnofossils, right under the Irati bed, were reported (Chahud et al., 2010a) Very fine sandstones and siltstones, massive or finely laminated Defined by very well sorted brownish white, very fine sandstone to siltstone, mostly massive, sometimes parallel or cross laminated.Some lateral variation in granulometry occurs but never over fine sandstones.
Scarcely fossiliferous, these strata contain rare arthropods (conchostracans and indeterminate crustaceans), fish scales and loose remains.The fossils are recognized only in unweathered samples.Occasionally they occur right in sharp contact with the Taquaral Member of the Irati Formation, which are either coarse sandstones or siltstones (Assine et al., 2003;Chahud et al., 2010a;Chahud and Petri 2013a;2013b).

Conglomerates
Conglomerate, informally known as the Ibicatu facies since Soares (1972), contains siliceous pebbles one to three centimeters in size, "floating" in a light brown coarse sandstone matrix.
The type locality was a road cut later destroyed by road widening.It was six meters thick, according to Fúlfaro et al. (1984) and Stevaux et al. (1986).Right above, in sharp contact, came deposits of the Taquaral Member of the Irati, reported by these researchers.
The type section had a significant amount of large plant fossils, specimens that reach nearly one meter (Figs. 2 and 3).
Conglomerates, like the Ibicatu, were reported in other outcrop localities from the State of São Paulo but stratigraphically not in contact with the Irati (Stevaux et al., 1986;Assine et al., 2003;Chahud, 2011;Chahud et al., 2012), with sigmoidal structure, and ichnofossils are present in the upper beds.However, these structures were not present in the type locality (Stevaux et al., 1986).The upper Tatuí Formation, here discussed, is sketched in figure 3. It must be placed in the Late Paleozoic third order sequence of the Tatuí, LPTS-4, of Holz et al. (2010).These authors believe this sequence to be middle Artinskian in age.However, it is possible that the base of Tatuí Formation, not discussed in that paper, might be placed in an older sequence, LPTS3.

PALEONTOLOGY Ichnofossils
Bioturbated deposits were recorded with two morphotypes in two Tatuí Formation lithologies.The first was described by Chahud et al. (2012) in lithology 1, below deposits interpreted by the authors as representing a freshwater paleoenvironment (lithology 2).
The structures are simple irregular conical excavations, irregular oval or elongate openings lay down in seen both from above and perpendicular to the beds (Fig 4A -B).
Several ichnogenera might be applied to this kind of excavation.It is not a good paleoenvironmental index, present under fresh or salty shallow waters or even subaerial.The second morphotype (Fig. 4C) is seen in poorly sorted sandstone with sigmoidal structure interbedded with silty beds (lithology 3 Fig.3), observed in outcrop as a lateral extension of the remainder of the destroyed Ibicatu type-locality.
It is a set of horizontal trails of 5mm width with simple ramifications, without preferential direction, many tracks cut perpendicular or askew other trails.There are no spines, paws, claws or any ornamentation, just smooth trails and structureless fill with lithology similar to host rock.The structures are preserved in negative and positive relief, this being the most common.
Several biogenic perforations occur at the interface Tatuí-Taquaral (lithologies 1 and 4, Fig. 3).Animals that lived at the beginning of Taquaral deposition, right after the final of Tatuí deposition, were responsible for these structures.

Plant fossils
Only sparse, isolated, fragmented remains of plant fossils in the Tatuí beds have been reported in the literature.The first occurrences of larger and better-preserved specimens came from the Ibicatu conglomerate (Fúlfaro et al., 1984;Assine et al., 2003;Chahud and Petri, 2009a).
These fossils, the largest of the present study, are Pteridophyta and Spermatophyta trunks.The great Pteridophyta fragments of elongate stems (fig.5A and B), several centimeters long, were investigated by Chahud (2011), who placed them in the genus Tietea (Solms-Laubach, 1913), by the shape of the meristeles, similar to those described by Derby (1915) and Tavares (2007), at the Corumbataí Formation, units younger than Tatuí, and also by the absence of the organized meristeles in the central part of the stele, features which exclude the genus Psaronius, with well defined and organized meristeles.Herbst (1987) described similar plants from the Permian of Paraguay, proposing the genus Tuvichapteris, also with unorganized meristeles and the stem center like Tietea.The differences between these two genera would be the number of fronds sprouted out from the trunk.The Ibicatu specimens did not preserve them.Tavares et al. (2011), however, argued against the value of the frond differences, which would be caused by the difference of ontogenetic stages, so the priority goes to the name of the genus as Tietea.
Another kind of Ibicatu stem, but smaller and apparently less frequent, was attributed to Spermatophyta.It is a gymnospermic cylindrical type (Fig. 5C-D), compact and deformed and irregularly elongate.
The plant fossils were dispersed among the conglomerate with clasts 5mm to 3cm in size.None of the fossils are in "life position", each laid down horizontally by the current, which direction was registered as E-W for the two kinds of the stems.Previously Stevaux et al. (1986) reckoned a sole N-S direction for the fossils, before the destruction of the outcrop.
Diagenesis acted before final fossilization, mainly through compression by sediment inflow, increasing the fossil widths and deformations.Bar-scale 50mm D) cross-section.Bar-scale 20mm.

Arthropods Conchostracans
They are preserved as impressions with few external morphological features.Sometimes the umbo is easily seen.The entire outline of growth lines is scarcely observed.No thicknesses neither concave -convex shapes are detected.
The best-preserved specimens allowed distinction of the valves as oval rounded in outline (Fig. 6A and B) similar to both recent and Paleozoic forms (Brito et al., 2000;Ferreira de Oliveira, 2007).However, it is not possible to classify them at the genus level, based only on the features noted above.
A lot of packed conchostracans were reported in a silty laminated bed (Fig. 3) with characteristics of free -settling and absence of traction action (Chahud et al., 2012).These fossils are packed as a "shell bed", interbedded with others with less numerous fossils.The assemblage concentration changes upward and sideward.
Other Crustaceans Mezzalira and Martins Neto (1992) are the only researchers to record Crustaceans (no conchostracan) in the Tatuí Formation.The two genera, Pseudopalaega, and Protourda are rather poorly preserved isopods, associated with fish remains and conchostracans.Chahud et al. (2012) reported unidentified crustaceans in massive finely laminated sandstones and siltstones (Fig. 6C)

Paleovertebrates
Some vertebrates are also associated with the conchostracans and others scarcely present in the fine sandstones with hummocky (Ragonha,1978;Chahud and Petri, 2009c).A unique identification of a semi-articulated fish, Actinopterygii, a kind of Platysomoidea, was reported by Silva Santos (1991).The Mezzalira and Martins Neto (1992)'s crustaceans came from the same outcrop.
The fossils, as a rule, were preserved as scales and loose teeth of the Palaeonisciformes and Coelacanthimorpha, dispersed and fragmented among the matrix (Fig. 6E-F).

Other fossils
Rare fossils, assigned to the Tatuí beds, were mentioned in papers published before this contribution.Most of them were placed in beds wrongly thought to belong to the Tatuí Formation.Barbosa and Almeida (1949) and Almeida and Barbosa (1953) reported sponge spicules in beds believed to be Tatuí.They neither described nor illustrated the spicules, furthermore the stratigraphic position of the beds is uncertain.
Three foraminifera genera, Erlandia, Ammodiscus, and Hyperamina, were reported by Fúlfaro et al. (1984) in silty sandstones.These fossils came from the basal beds of the Tatuí, and would be probably a continuation of the conditions of deposition of the upper Itararé Group.Lima et al. (1976) recognized Ammodiscus and Hyperamina in the Itararé beds.Cabral Jr. et al. (1988) reported agglutinated foraminifera, ostracods, and acritarchs from core wells from the base and top of a section attributed to the Tatuí.However, the lower cores might belong to the Itararé, and the upper might belong to the base of the Taquaral Member.Cabral Jr. et al. (1988) didn't describe and illustrate them, and only acritarchs were confirmed by Marasco et al. (1993) in the base of the Taquaral Member.

Conclusions And Paleoenvironmental Considerations
The record of the entire Tatuí Formation fossils are ichnofossils, plant fossils, bones of fishes and arthropods.Only ichnofossils and fishes are reported in more than one lithology (coarse and fine sandstones).
The Tatuí Formation paleoenvironment of deposition evolved through three phases.The first apparently contains only the euryhaline fossils, agglutinated foraminifera mentioned by Fúlfaro et al. (1984).These fossils are common in brackish waters may be transitional from coastal estuary complex to coastal marine.
Another two phases, from the upper Tatuí, reflect the interplay of two paleoenvironments.
The deposits of the second phase are regressive and continental, with conchostracans dropped downward without further transportation, in a lacustrine deposit, within the siltstones massive or laminated beds (lithology 2, Fig. 3), and large plant stems in the conglomerates (lithology 3, Fig. 3), fluvial deposits.
The third phase is transgressive with hummocky cross -stratification and, probably, increasing salinity, similar to the first stage (lithology one contact with lithology four, Fig. 3).

Figure 1 .
Figure 1.Outcrop belt of the Tatuí Formation in the State of São Paulo.