The westward lithospheric drift, its role on the subduction and transform zones surrounding Americas: Andean to cordilleran orogenic types cyclicity

ARAGÓN, EUGENIO; D'ERAMO, FERNANDO JAVIER; CUFFARO, MARCO; DOGLIONI, CARLO; FICINI, ELEONORA; PINOTTI, LUCIO PEDRO; NACIF, SILVINA; DEMARTIS, MANUEL; HERNANDO, IRENE; FUENTES, TOMÁS

Geoscience Frontiers

Elsevier

Lugar: Beijing; Año: 2020

1674-9871

Weinvestigate the effect of the westerly rotation of the lithosphere on theactive margins that surround the Americas and find good correlations betweenthe inferred easterly-directed mantle counterflow and the main structural grainand kinematics of the Andes and Sandwich arc slabs. In the Andes, thesubduction zone is shallow and with low dip, because the mantle flow sustainsthe slab; the subduction hinge converges relative to the upper plate andgenerates an uplifting doubly verging orogen. The Sandwich Arc is generated bya westerly-directed SAM (South American) plate subduction where the eastwardmantle flow is steepening and retreating the subduction zone. In this context,the slab hinge is retreating relative to the upper plate, generating thebackarc basin and a low bathymetry single-verging accretionary prism. InCentral America, the Caribbean plate presents a more complex scenario: a) Tothe East, the Antilles Arc is generated by westerly directed subduction of theSAM plate, where the eastward mantle flow is steepening and retreating thesubduction zone. b) To the West, the Middle America Trench and Arc aregenerated by the easterly-directed subduction of the Cocos plate, where theshallow subduction caused by eastward mantle flow in its northern segmentgradually steepens to the southern segment as it is inferred by the preexistingwesterly-directed subduction of the Caribbean Plateau.In the frame of the westerly lithospheric flow, the subduction of adivergent active ridge plays the role of introducing a change in theoceanic/continental plate?s convergence angle, such as in NAM (North American) platewith the collision with the Pacific/Farallon active ridge in the Neogene(Cordilleran orogenic type scenario). The easterly mantle drift sustains strongplate coupling along NAM, showing at Juan de Fuca easterly subducting microplatethat the subduction hinge advances relative to the upper plate. Thislower/upper plate convergence coupling also applies along strike to theneighbor continental strike slip fault systems where subduction was terminated(San Andreas and Queen Charlotte). The lower/upper plate convergence couplingenables the capture of the continental plate ribbons of Baja California andYakutat terrane by the Pacific oceanic plate, transporting them along thestrike slip fault systems as para-autochthonous terranes. This Cordilleranorogenic type scenario, is also recorded in SAM following the collision withthe Aluk/Farallon active ridge in the Paleogene, segmenting SAM margin into theeastwardly subducting Tupac Amaru microplate intercalated between theproto-Liqui~ne- Ofqui and Atacama strike slip fault systems, where subductionwas terminated and para-autochthonous terranes transported. In the Neogene, theconvergence of Nazca plate with respect to SAM reinstalls subduction and the presentAndean orogenic type scenario.