title: Siamaná Formation
text: # Siamaná Formation
  
  The Siamaná Formation (Spanish: Formación Siamaná, E3s) is a fossiliferous geological formation of the Cocinetas Basin in the northernmost department of La Guajira. The formation consists of conglomerates and limestones. The Siamaná Formation dates to the Paleogene period; Middle to Late Oligocene epoch, corresponding to the Deseadan in the SALMA classification.
  
  ## Etymology
  
  The formation was defined by Renz in 1960 and named after the village of Siamaná.
  
  ## Description
  
  ### Lithologies
  
  The Siamaná Formation consists of conglomerates and thick carbonates.
  
  ### Stratigraphy and depositional environment
  
  The Siamaná Formation, with a maximum thickness of 430 metres (1,410 ft), overlies the Macarao Formation and is overlain by the Uitpa Formation. The age has been estimated to be Middle to Late Oligocene, corresponding to the Deseadan in the SALMA classification. The depositional environment has been interpreted as shallow marine.
  
  ### Petroleum geology
  
  The Siamaná Formation is a reservoir and seal rock formation in the Guajira Basin.
  
  ### Fossil content
  
  | Group | Fossils | Notes |
  | - | - | - |
  | Invertebrates | Mimachlamys canalis, Ostrea sp. | |
  