Topic
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.
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TL;DR: In this paper, the existence of an autochthonous Stenian-Tonian belt in northern Amazonia that is undisturbed by Andean orogenesis has not been recognized so far.
139 citations
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TL;DR: In this article, the authors provide new field observations and isotopic data for key areas of the Central Asian Orogenic Belt (CAOB), reiterating their previous assessment that no excessive crustal growth occurred during its ca. 800 Ma long orogenic evolution.
138 citations
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TL;DR: In this paper, the authors constructed a geodynamic model for the Cretaceous-Tertiary evolution of the Northern Andes and placed important new constraints on the extent of oceanic plateau sequences in Colombia and around the Caribbean.
Abstract: Western Ecuador consists of a complex tectonic me´lange of oceanic terranes accreted to the
continental margin from Late Cretaceous to Eocene time. New geochemical data from these accreted terranes
(arising from a 5 year British Geological Survey mapping programme) indicate that they comprise rocks from
a variety of oceanic tectonic settings: from thickened (and relatively unsubductable) oceanic plateau basalts,
through island-arc tholeiites, with occasional more calc-alkaline lavas, to back-arc basin basalt sequences.
This study has enabled us to construct a new geodynamic model for the Cretaceous–Tertiary evolution of the
Northern Andes, and has placed important new constraints on the extent of oceanic plateau sequences in
Colombia and around the Caribbean. The age and nature of sediments, combined with evidence for the age of
peak metamorphism, suggests that a prolonged (15–20 Ma) accretionary event occurred in Late Cretaceous
time and involved the collision of an oceanic plateau (represented by the Pallatanga Unit) with the continental
margin. This accreted unit can be correlated with similar oceanic plateau sequences from the Western
Cordillera of Colombia and those within and around the Caribbean region. The Naranjal and Macuchi island
arcs and the associated La Portada back-arc basin developed along the accreted margin from Late Campanian
to Eocene time, and these arcs accreted to the continental margin along with oceanic plateau material
(represented by the Pin˜on Unit and Pedernales–Esmeraldas sequences) during Eocene time. The development
of island arcs, which separate the two accretionary events, implies that the most westerly (coastal) oceanic
plateau sequences, both in Ecuador (Pin˜on and Pedernales–Esmeraldas) and in Colombia (Gorgona and
Serrani´a de Baudo´ ), cannot belong to the Caribbean–Colombian Oceanic Plateau (CCOP). It therefore appears
that at least two different oceanic plateaux are preserved within the accreted oceanic terranes of the Northern
Andes. It is possible that the CCOP formed over the Gala´pagos hotspot, as previously proposed, but the more
westerly Coastal plateau was derived from a more southerly hotspot source region, such as Sala y Gomez, in
the SE Pacific.
138 citations
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TL;DR: In this article, the authors present an overview on the lithology, geochemistry, geochronology, Lu-Hf isotopes and metamorphic history of the Neoarchean to Paleoproterozoic rocks in the major basement terranes from the central segment of the TNCO.
138 citations
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TL;DR: In the southern Rio Grande rift, two extensional regimes of different origin (but transitional with each other through the Miocene) can be interpreted from structures and rocks formed within the past 28 to 29 m.y.p. as discussed by the authors.
Abstract: In the southern Rio Grande rift, two extensional regimes of different origin (but transitional with each other through the Miocene) can be interpreted from structures and rocks formed within the past 28 to 29 m.y. The earlier regime, which began about 28 to 29 m.y. B.P., is characterized by emplacement of “basaltic andesite” flows with relatively high strontium isotope ratios; formation of broad, relatively deep, northwest-trending basins; and incipient uplift of some of the region9s fault-block mountains. This regime appears to have developed in a back-arc setting, perhaps behind a rapidly steepening slab and a westward-sweeping arc system. The younger episode seemingly represents a renewal or acceleration of block faulting and volcanism during the latest Miocene and Pliocene, 9 to 3 m.y. B.P., after a long transitional period during the early and mid-Miocene when volcanism was absent and tectonism was less vigorous. The latest Miocene-Pliocene episode produced the modern northerly-trending rift basins and uplifts, regional uplift of the rift 1 to 2 km above sea level, and renewal of volcanism, this time dominated by relatively primitive alkali-olivine basalt. New basalt dates reveal that in the southern rift, modern ranges and basins were almost fully developed and that near-modern drainage ways were established across uplifts into bolsons by about 5.0 m.y. B.P. An ancestral Rio Grande had extended itself southward into the southern rift by 3 to 4 m.y. B.P., and the river entrenched itself into its modern valley between 0.7 and 0.5 m.y. B.P. Horst-graben development of the southern Basin and Range province, as well as associated basaltic volcanism, swept progressively eastward from southeastern California in the past 20 m.y., culminating in formation of the Rio Grande rift and other fault-block terrane in west Texas, New Mexico, and northern Chihuahua in the latest Miocene and Pliocene. Late Quaternary Basin and Range fault scarps increase in density eastward, which also suggests that more easterly parts of the province are youngest. These relationships support a previous model of an eastward-expanding, slab-free triangle (related to growth of the San Andreas transform), through which mantle upwelling triggers eastward-younging patterns of tectonism, volcanism, and uplift and promotes lithospheric thinning and increased heat flow. Across most of the southern Basin and Range and Rio Grande rift, the horst-graben structures related to growth of this triangle are superimposed on somewhat older (late Oligocene-middle Miocene) extensional terrane that appears to have formed in a back-arc or arc setting.
138 citations