The Marañón fold and thrust belt (Spanish: faja corrida y plegada del Marañón) is a 1,000 kilometres (620 mi) long, northwest–southeast trending belt of deformed rocks located in the Andes of central Peru.[1][2] The formation of the belt defines the Incaic Phase of the Andean orogeny.[note 1]
Prior to the deformation and uplift the rocks forming the Marañón fold and thrust belt constituted the fill of a marine back-arc basin that existed in the Mesozoic and was parallel to the present-day coast.[4] The west-dippingChonta Fault existed as a normal fault within this basin and allowed continued basin subsidence and sediment accumulation in the Mesozoic.[5] The onset of Andean orogeny first caused the basin to rise and dry up with red beds being deposited in its eastern part. Then the sedimentary basin was subject of a complete basin inversion.[4] During deformation Chonta Fault acted as a barrier "damming-up" folded and thrust strata west of it. This makes the fault define the limits of two different styles of thin-skinned deformation within the belt. The fault was reactivated as an inverse fault during basin inversion in the Eocene.[5]
^The Incaic Phase is one of the main structural events in central Peru defined originally in a 1929 posthumous publication of Gustav Steinmann (1856–1929).[3]
^ abScherrenberg, Arne F.; Konh, Barry P.; Holcombe, Rodney J.; Rosenbaum, Gideon (2016). "Thermotectonic history of the Marañón Fold–Thrust Belt, Peru: Insights into mineralisation in an evolving orogen". Tectonophysics. 667: 16–36. Bibcode:2016Tectp.667...16S. doi:10.1016/j.tecto.2015.11.007.