Santa-Maria-Formation

The Santa Maria Formation is a lithostratigraphic formation sedimenären origin from the Middle Triassic of southern Brazil. It belongs to the Santa Maria Super sequence from the Rosario -do- Sul group and thus to the Paraná Basin deposited Gondwana II Super sequence. The formation has a very rich vertebrate fauna.

Etymology

The formation is named after the city of Santa Maria in the Brazilian state of Rio Grande do Sul.

Stratigraphy

The Santa Maria lineup comes with an erosive unconformity to lie on the overlapping among Sanga -do Cabral Formation, in which it has been cut with sandstone and conglomerate lenses documents their lowest members. In the hanging wall of it goes into the sand auflagernde stressed Caturrita lineup with a gradual facies changes taking place.

The Santa Maria Formation is subdivided into two members ( from young to old):

  • Alemoa Members
  • Pass - the - Tropas Members

Sequence Stratigraphy

The 200 meter wide Santa -Maria- Super sequence, a second-order cycle, in turn, can be separated into third-order cycles ( from young to old):

  • Santa -Maria- Sequence 3 - Mata Sandstone - sea level high stand
  • Santa -Maria- Sequence 2 - Caturrita Formation ( upper portion) and Alemoa Members (lower section) - up to 130 meters - Transgression
  • Santa -Maria- sequence 1 - Alemoa Members and basal Passo - the - Tropas Members - 50 meters - sea level depression

So the Santa Maria Formation covers the entire Santa -Maria- sequence 1 and the lower part of the Santa Maria sequence 2

Age

For the Santa Maria Formation is no absolute age information available, but it is placed in the Ladinian and Carnian basis of their fossil content.

Distribution area

The distribution area of the Santa Maria Formation is restricted to the Brazilian state of Rio Grande do Sul. She pulls in a relatively narrow ( with a maximum Ausstrichsbreite of about 30 kilometers ), 250 -kilometer-long belt in east-west direction of Taquari up to Mata.

Ablagerungsbedingunen and facies

The Passos - the - Tropas Members begins as " Lowstand systems tract " - abgesunkenem at sea level, it eroded heavily in its base, the Sanga do Cabral - formation. In order to deposit fine-grained came to conglomeratic sandstones, subordinate siltstones and mudstones and red, ranging from very high energy fluxes ( Zopfströmen ) were delivered with relatively low curvature. It ruled semi-arid climatic conditions.

The Alemoa member is a ' transgressive systems tract ', with rising sea red clays were sedimented. The early diagenetic carbonate content contained in them suggests visibly dry climatic conditions. The mudstones were to be deposited either in shallow lakes or floodplains of ephemeral Zopfstromsystems. The latter sedimentation and the red color of the sediments indicate a climate with distinct seasons. Type locality of Alemoa - Members are the outskirts of Santa Maria.

Fossil content

The Santa Maria sequence 1 houses an important vertebrate Biozone, the " Dinodontosaurus Assemblage Zone ", named after the Dicynodontier Dinodontosaurus pedroanum. The Biozone is not sharply defined, so in addition, a sub-zone stratigraphically slightly higher lying are reported, the " Stahleckeria Zone ", named after Stahleckeria potens, also a Dicynodontier. Associated with the Dinodontosaurus - Biozone, there are the following taxa:

  • Barbarenasuchus brasiliensis ' - archosaurs
  • Candelaria barbouri - Owenetide ( Temnospondyle )
  • Chiniquodon theotonicus - cynodonts
  • Exaeretodon major - cynodonts
  • Ischigualastia - Dicynodontier
  • Jachaleria candelariensis - Dicynodontier
  • Luangwa Sudamericana - cynodonts
  • Massetognathus ochagaviae - cynodonts
  • Prestosuchus chiniquensis - archosaurs
  • Procerosuchus celer - archosaurs
  • Protheriodon estudianti - cynodonts
  • Santacruzodon hopsoni - cynodonts
  • Spondylosoma absconditum - archosaurs
  • Traversodon stahleckeria - cynodonts

Represented are also several Traversodontiden and a rhadinosuchider archosaurs. The main sites are at Chiniquá and Pinheiros.

The Alemoa Members in the lower section of the Santa Maria sequence 2 also contains a very important vertebrate Biozone, the " Hyperodapedon assemblage zone ". The genus belongs to the Hyperodapedon Rhynchosauriern and occurs with three types:

  • Hyperodapedon huenei
  • Hyperodapedon mariensis
  • Hyperodapedon sanjuanensis

Associated with the Hyperodapedon - Biozone following taxa are also:

  • Aetosauroides - archosaurs
  • Cerritosausus binsfeldi - archosaurs
  • Gomphodontosuchus brasiliensis - cynodonts
  • Prozostrodon brasiliensis - cynodonts
  • Rauisuchus Tiradentes - archosaurs
  • Rhadinosuchus gracilis - archosaurs
  • Saturnalia Tupiniquim - Dinosaurs
  • Staurikosaurus pricei - Dinosaurs
  • Teyuwasu barbarenai - Dinosaurs
  • Therioherpeton cargnini - cynodonts

To day also were the remains of a Temnospondylen. The main sites are located in and around Santa Maria.

Santa Maria (Rio Grande do Sul) Caturrita-Formation Desert climate Diagenesis Paleontological Site Arroio Cancela
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