Yamanasaurus lojaensis gen. et sp. nov. is a new titanosaur (Saurischia, Sauropoda) from the Upper Cretaceous of the Alamor-Lancones Basin, southern Ecuador. The fossil remains were found in rocks of ...the Río Playas Formation, which is regarded as Campanian–Maastrichtian in age. Remains include a partial sacrum, a partial mid-caudal vertebra, and several associated limb bones. Yamanasaurus is characterized by: (1) anterior to mid-caudal vertebrae with a dorsoventrally compressed condyle, with the posterior tip elevated respect to the midline, no longitudinal ventral ridge, and spongy inner structure with absence of internal cavities (i.e., camellate bone, shared with Neuquensaurus); (2) last sacral centrum as long as tall, with small ovoid, shallow blind fossa on the lateral side; and (3) radius robust with flattened diaphysis and a marked neck or cingulum right under the epiphysis, with an heptagonal concave proximal surface. Morphology, size, and age suggest that Yamanasaurus is closely related to Neuquensaurus, being the northernmost saltasaurine known by far.
The Cretaceous Alamor-Lancones Basin is located in the forearc region of southern Ecuador and northern Peru. The eastern (Río Playas) domain includes the upper stratigraphic levels of the 1800 m ...thick basin-fill succession. Sedimentological, provenance and chronostratigraphic analyses of the Río Playas region help to elucidate the Late Cretaceous to Eocene evolution of the forearc region in southern Ecuador and neighboring regions.
The oldest strata of the Río Playas region include Lower Cretaceous volcanic and volcaniclastic deposits of the Celica and Alamor formations, which were deposited in an arc-related extensional basin. These units are unconformably overlain by the Coniacian to Maastrichtian El Naranjo and Casanga formations. Lithofacies described for the El Naranjo and Casanga formations include sandy debrites, sandy turbidites, silty-muddy turbidites, sandy slumps, clast-supported debrites and rafted blocks. These lithofacies association suggests a deepwater submarine fan depositional environment.
Provenance analyses for the Casanga and El Naranjo formations, including heavy mineral and petrographic data, show that these formations were derived from erosion of a volcanic arc and a minor granitic and metamorphic source terrane. Detrital zircon U-Pb ages for the Casanga Formation indicate contributions from Santonian age sources, which partially overlap stratigraphic ages, suggesting volcanism contemporaneous with deposition. In addition, paleocurrent analyses indicate sediment transport to the southeast, pointing to a sediment source along the South American margin.
Volcanic and volcaniclastic rocks of the Paleocene Sacapalca Formation overlie the Casanga and Naranjo formations in angular unconformity. The Sacapalca Formation passes transitionally into fluvial sandstone, conglomerate and red beds of the Río Playas Formation. Overall, the succession recorded a transition from volcanic to alluvial fan deposition. Heavy mineral and sandstone QFL analyses show a significant input of metamorphic detritus in the Río Playas Formation, which indicates derivation from the Cordillera Real. This interpretation is also supported by detrital zircons of Proterozoic age. The change from submarine fan deposits of the El Naranjo and Casanga formations to the nonmarine Río Playas Formation suggests exhumation in response to an important tectonic event, likely deformation related to collision of the Caribbean Plateau to South America at 73–70 Ma.
•Provenance analyses of the Río Playas region elucidate the Cretaceous to Eocene evolution of the Alamor-Lancones Basin.•El Naranjo and Casanga formations were deposited by sediment gravity-flows in a deep-marine environment.•The volcanic record of Sacapalca Formation shows volcanic arc migration from Early Cretaceous to Paleocene time.•Río Playas Formation was deposited in an alluvial fan environment.•Exhumation of Alamor-Lancones Basin was driven by collision of the Caribbean Plateau.
A reappraisal of the “Late Cretaceous Yunguilla Formation” of the Cuenca area enables the definition of four distinct formations, correlatable with those of southwestern Ecuador. A mid- to ...late-Campanian marine transgression (Jadán Formation) is overlain by quartz-rich conglomerates of fan-delta to turbiditic fan environment (Quimas Formation) of latest Campanian–earliest Maastrichtian age, which are interpreted as evidence of the accretion of a first oceanic terrane (San Juan). Disconformable, arkosic turbidites and cherts (Tabacay Formation) of early Maastrichtian age are thought to represent the erosion of the newly accreted oceanic terrane. A major unconformity of late Maastrichtian age, caused by the accretion of a second oceanic terrane (Guaranda), is followed by the deposition of quartz-rich micaceous shelf sandstones (Saquisilí Formation) of Paleocene age. A third accretion event (late Paleocene) is recorded in coastal Ecuador. Each accretion event correlates with the uplift and erosion of the Eastern Cordillera and with a sedimentary hiatus in the eastern areas. In Ecuador, accretion of oceanic terranes contributed to the build up of the Andes through tectonic underplating of low-density material, and the eastern areas did not behave as flexural foreland basins during late Cretaceous–Paleogene times.
The eastern part of the “Celica basin” of southwesternmost Ecuador exhibits Late Cretaceous to Tertiary sediments which belong to the magmatic arc paleogeographic zone. Important N-S to NE-trending ...faults separate a western, mainly Late Cretaceous series (Río Playas) from an eastern succession (Catamayo-Gonzanamá) of (?) Late Cretaceous to early Tertiary age. The analysis of these sediments indicates a complex geologic history, which recorded the main stages of the early tectonic evolution of the Andes.
In the Río Playas area, a submarine andesitic volcanic pile (Celica Fm) represents the products of a volcanic arc of probably Albian age. It is apparently overlain by a thick, early Late Cretaceous series of volcanic flows and coarse-grained volcaniclastic high-density turbiditic beds (Alamor Fm), the deposition of which might result from the Mochica phase (late Albian-early Cenomanian) Deformation, uplift and erosion (early Peruvian phase) are followed by the sedimentation of unconformable marls and greywackes of marine open shelf to deltaic environment. These comprise Santonian and/or Campanian fine- to mediumgrained deposits (Naranjo Fm), abruptly overlain (late Peruvian phase ?) by fan-delta coarse-grained marine deposits of latest Cretaceous age (Casanga Fm) They are locally capped by undated, partly volcaniclastic red beds, indicating an important regression/uplift of latest Cretaceous-early Tertiary age.
In the Catamayo-Gonzanamá area, thick subaerial andesitic volcanic rocks (Sacapalca Fm) are intruded by Paleocene to early Eocene plutons and are overlain by undated fluvial red beds. They express uplift movements of latest Cretaceous-early Tertiary age. To the South, these are capped by slumped lacustrine black shales and greywackes of possible Maastrichtian-Paleocene age (Gonzanamá Fm) Farther north, the Sacapalca volcanics and red beds are overlain by variegated shales, sandstones and conglomerates, dated as latest Oligocene-early Miocene (Catamayo Fm) They are eroded by an angular unconformity and capped by early Miocene volcanics and sediments, which express an early Miocene deformation phase. The apparent sedimentary hiatus including most of Eocene-Oligocene times is interpreted as a result of the late Paleocene and late Eocene Incaic tectonic phases.
La parte oriental de la “Cuenca Celica” del Suroeste ecuatoriano presenta sedimentos del Cretáceo superior al Terciario, que pertenecen a la zona paleogeográfica del arco magmático andino. Importantes fallas de dirección N-S separan una serie occidental, mayormente del Cretáceo superior (Río Playas), de una serie oriental (Catamayo-Gonzanamá) de edad Cretaceo superior (?) y Terciario inferior. El análisis de estos depósitos evidencia una historia geológica compleja, que registró las etapas principales de la evolución tectónica precoz de los Andes.
En la zona de Río Playas, volcánicos andesíticos submarinos (Fm Celica) representan los productos de un arco magmático de probable edad albiana. Parecen ser sobreyacidos por una serie potente de coladas volcánicas y turbiditas volcano-clásticas de alta densidad (Fm Alamor) Su deposición podría ser relacionada con la fase tectónica Mochica del Albiano superior-Cenomaniano inferior. Estas rocas fueron levantadas y erosionadas (fase Peruana temprana) antes del depósito discordante de margas de plataforma marina y grauacas deltaicas. Estas comprenden depósitos de grano fino de edad Santoniano y/o Campaniano (Fm Naranjo), abruptamente sobreyacidos (fase Peruana tardía ?) por conglomerados marinos de cono aluvial costero (fandelta) del Cretáceo terminal (Fm Casanga) La serie se termina localmente con capas rojas no datadas, en parte volcanoclásticas, que indican una regresión y/o un levantamiento de edad Cretáceo terminal o Terciario inferior.
En la zona de Catamayo-Gonzanamá, una espesa serie de rocas volcánicas andesiticas subaéreas (Fm Sacapalca) está intruida por plutones del Paleoceno a Eoceno inferior, y sobreyacida por capas rojas fluviátiles no datadas, que expresan un levantamiento importante en el Cretáceo superior-Terciario inferior. Hacia el Sur, están sobreyacidas por lutitas negras y grauacas lacustres de posible edad maastrichtiana-paleocena, con deformaciones sinsedimenatrias (Fm Gonzanamá) Hacia el Norte, los volcánicos y capas rojas Sacapalca están sobreyacidos por lutitas, areniscas y conglomerados abigarrados, datados del Oligoceno terminal a Mioceno inferior (Fm Catamayo) Estos están erosionados por volcánicos y sedimentos del Mioceno inferior, lo que indica una deformacián de edad Mioceno inferior. El hiato aparente de gran parte del Eoceno-Oligoceno está interpretado como una consecuencia de las fases tectónicas incáicas del Paleoceno superior y Eoceno superior.
Monastirile dobrogene descrise de Arhimandritul Roman Sorescu, starițul Monastirei Cocoș-Saun din județul Tulcea
1914
Web Resource
Open access
Antetul: Nifon, Episcopul Dunării de Jos - prefațator.
Prefața este semnată de Nifon, Episcopul Dunării de Jos, datată Galați, 22 martie 1914 (p. III-V). Arhimandritul Roman Sorescu (1876-?) a fost ...hirotonit pe seama mănăstirii Ciolanu, apoi a fost transferat la Episcopia din Buzău, la Mănăstirea Sinaia și ulterior a trecut în Eparhia Dunării de Jos (portret, p. 48). Autorul aduce în monografie și o serie de documente. Planșele adăugate lucrării reprezintă: planul general al construcțiilor mănăstirii Cocoș; planul vetrei mănăstirii Cocoș; planul general al mănăstirii Celic-Dere; planul mănăstirii Celic-Dere din 1910; planul vetrei schitului Saon.
PDF
