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

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

Geoscience Frontiers

Elsevier

Lugar: Beijing; Año: 2020 vol. 11 p. 1219 - 1229

1674-9871

We investigate theeffect of the westerly rotation of the lithosphere on the activemargins that surround the Americas and find good correlations betweenthe inferred easterly-directed mantle counterflow and the mainstructural grain and kinematics of the Andes and Sandwich arc slabs.In the Andes, the subduction zone is shallow and with low dip,because the mantle flow sustains the slab; the subduction hingeconverges relative to the upper plate and generates an upliftingdoubly vergin orogen. The Sandwich Arc is generated by awesterly-directed SAM (South American) plate subduction where theeastward mantle flow is steepening and retreating the subductionzone. In this context, the slab hinge is retreating relative to theupper plate, generating the back-arc basin and a low bathymetrysingle-verging accretionary prism. In Central America, the Caribbeanplate presents a more complex scenario: a) To the east, the AntillesArc is generated by westerly directed subduction of the SAM plate,where the eastward mantle flow is steepening and retreating thesubduction zone. b) To the west, the Middle America Trench and Arcare generated by the easterly-directed subduction of the Cocos plate,where the shallow subduction caused by eastward mantle flow in itsnorthern segment gradually steepens to the southern segment by thepreexisting westerly-directed subduction of the Caribbean Plateau.In the frame of thewesterly lithospheric flow, the subduction of a divergent activeridge plays the role of introducing a change in theoceanic/continental plate?s convergence angle, such as in NAM(North American) plate with the collision with the Pacific/Farallonactive ridge in the Neogene (Cordilleran orogenic type scenario). Theeasterly mantle drift sustains strong plate coupling along NAM,showing at Juan de Fuca easterly subducting microplate that thesubduction hinge advances relative to the upper plate. Thislower/upper plate convergence coupling also applies along strike tothe neighbor continental strike slip fault systems where subductionwas terminated (San Andres and Queen Charlotte). The lower/upperplate convergence coupling enables the capture of the continentalplate ribbons of Baja California and Yakutat terrane by the Pacificoceanic plate, transporting them along the strike slip fault systemsas para-autochthonous terranes. This Cordilleran orogenic typescenario, is also recorded in SAM following the collision with theAluk/Farallon active ridge in the Paleogene, segmenting SAM margininto the eastwarly subdcting Tupac Amaru microplate intercalatedbetween the proto-Liquiñe-Ofqui and Atacama strike slip faultsystems, where subduction was terminated and para-autochthonousterranes transported. In the Neogene, the convergence of Nazca platewith respect to SAM reinstalls subduction and the present Andeanorogenic type scenario.p { margin-bottom: 0.25cm; line-height: 115% }