Terrane

About: Terrane is a research topic. Over the lifetime, 11025 publications have been published within this topic receiving 442596 citations. The topic is also known as: tectonostratigraphic terrane.

Geologic Evolution of the Sierra Nevada de Santa Marta, Northeastern Colombia

Abstract: New geologic, petrographic, and radiometric evidence (52 ages) from the Sierra Nevada suggest that plate tectonics controlled the complex Mesozoic evolution of the Caribbean continental margin. The triangular Sierra Nevada massif is bounded by the Oca fault, Santa Marta–Bucaramanga fault, and Cesar lineament. During the Tertiary, dextral and sinistral movement of 65 and 110 km, respectively, occurred along the Oca and Santa Marta–Bucaramanga faults; subsequently, several thousand meters of uplift produced the present geomorphic setting. Three metamorphic terranes are present; they differ petrographically and geochronologically and are separated by the Sevilla and Cesar lineaments (geosutures). The youngest terrane consists of three northeast-trending regional metamorphic; belts (Permian-Triassic gneiss, Jurassic schist, and Cretaceous-Paleocene green schist) that formed in successive subduction zones northwest of the Sevilla lineament. Tertiary plutons intrude this terrane. Most of the Sierra Nevada massif consists; of l,300-m.y.-old granulite terrane overlair by unmetamorphosed Paleozoic and Permian(?)-Triassic rocks and intruded by four northeast-trending belts of plutons that filled successive dilational rifts. These plutonic belts become younger, shallower, and more potassic in a southeastward direction. Extensional disruption, with transform separations up to 46 km, culminated with Middle Jurassic emplacement of two belts of composite batholiths and extensive ignimbritic eruptions. These events are related to the same southeast-dipping subduction zone that produced the Jurassic schist in the youngest metamorphic terrane. The third metamorphic terrane consists of younger(?) Precambrian amphibolite-grade rocks overlain by Silurian phyllites and unmetamorphosed Paleozoic and Mesozoic rocks that are typical of the Cordillera Oriental.

Lithospheric and upper mantle structure of central Chile and Argentina

Abstract: SUMMARY The tectonics of central Chile and Argentina have been greatly affected by the shallow dips of the subducting Nazca plate, which controlled patterns of magmatism and deformation nearly 1000 km away from the plate boundary. We calculate receiver functions from data recorded by the CHARGE array, which transected the Andes and Sierras Pampeanas in central Chile and Argentina, to better constrain the crustal structure of this region. Beneath the northern transect of the CHARGE array, where the Nazca slab flattens near 100 km, we find the crust is over 60 km thick beneath the Andes and thin to the east. The thick crust, however, extends ∼200 km to the east of the high elevations. Estimates of VP/VS obtained from receiver functions vary along ancient terrane boundaries exhibiting higher values to the west. Interestingly, we observe that the amplitude of the phase corresponding to the Moho on receiver functions diminishes to the west, complicating our images of crustal structure. We proposed that the observations presented here of thickened crust within a region of low elevations, diminished receiver function arrivals, and reports of high shear-wave speeds atop of the mantle wedge overlying the shallowly subducted Nazca slab, can be explained by partial eclogitization of the lower crust. The Moho appears simpler across the southern transect where it can be identified near 50 km depth at its deepest point beneath the Andes and shallows eastwards. Volcanism remains active near the latitudes of our southern transect and we observe multiple crustal lowvelocity zones indicative of regions of partial melt near the centres of volcanism. Signals related to the Nazca slab remain more elusive, suggestive of a small impedance contrast between the slab and overlying mantle.

Late Ordovician–Early Silurian continental collisional orogeny in southern Mexico and its bearing on Gondwana-Laurentia connections

Abstract: New zircon and monazite U-Pb data, tectonic mapping, and petrologic studies in key units of the Acatlan Complex show a previously undocumented phase of continental collision orogeny of Late Ordovician–Early Silurian age in southern Mexico. The event involved the partial eclogitization of oceanic lithosphere and continental crust, which traveled westward more than 200 km over siliciclastic metasedimentary rocks of the trench-forearc of an opposing continental margin. The overriding eastern margin was the Oaxaquia microplate attached to Gondwana, and the western overridden margin is considered to have been the eastern margin of Laurentia. This event, which we name the Acatecan orogeny, was roughly synchronous with the possible closure of Iapetus along the Appalachian margin, which involved, according to current models, either the docking of peri-Gondwanan terranes such as Avalonia and Carolina or the direct collision between Gondwana and Laurentia. The permanence of Oaxaquia in northwestern Gondwana until the end of the Silurian, as suggested by Tremadocian to Silurian marine faunas in the cover of Oaxaquia, is more consistent with the direct collision of Gondwana and Laurentia at the end of the Ordovician, forming the Acatlan Complex between.

Terranes of Mexico Revisited: A 1.3 Billion year Odyssey

Abstract: During the Precambrian and Paleozoic, Mexican terranes were either part of or proximal to Laurentia and Middle America (basements of Mesozoic Maya, Oaxaquia, and Chortis terranes that bordered Amazonia). Obduction of the Sierra Madre proximal terrane in the Late Ordovician was followed by Permo-Carboniferous amalgamation of all proximal terranes into Pangea. Middle Jurassic breakup of Pangea resulted in two continental terranes, Maya and Chortis, which were surrounded by small ocean-basin/arc terranes: Gulf of Mexico, Caribbean Sea, Juarez, Motagua terranes, and the Guerrero composite terrane. All of these terranes were obducted onto North America during the Late Cretaceous-Early Cenozoic, Laramide orogeny. Neogene propagation of the East Pacific Rise into the North American margin has led to separation and northwest translation of the Baja California terrane.