Geomorphological features of the Jurassic Granites in NE Nigeria (Southern Sahara)

2021 ◽  
pp. 1-26
Author(s):  
Aliyu Albishir Bashir ◽  
Murat Gül ◽  
Ceren Küçükuysal ◽  
Göksu Uslular
Keyword(s):  
Geomorphological Features

IDENTIFICAÇÃO DAS FEIÇÔES GRANÍTICAS DO MUNICÍPO DE IRAUÇUBA-CEARÁ

2019 ◽  
Vol 21 (2) ◽  
pp. 51-61
Author(s):  
Abner Monteiro Nunes Cordeiro ◽  
Rayane Barroso Araújo ◽  
Frederico De Holanda Bastos ◽  
Augusto César Praciano Sampaio
Keyword(s):  
Field Work ◽  
Granitic Rocks ◽  
Surface Erosion ◽  
Climatic Fluctuations ◽  
Geological Faults ◽  
Dry Climates ◽  
Evolution Understanding ◽  
Geomorphological Features

A exumação de rochas graníticas do Complexo Tamboril-Santa Quitéria, especificamente, na superfície de aplainamento do município de Irauçuba, Ceará, tem revelado uma grande variedade de feições geomorfológicas que se justificam por fatores litológicos e evidentes flutuações climáticas cenozoicas, comandadas, sobretudo, por morfogênese mecânica, associada a climas secos. São relevos residuais como, maciços, cristas, inselbergs, inselguebergs, lajedos e blocos saprolitizados (boulders) em diferentes graus de desenvolvimento que se sobressaem em meio à superfície erosiva rebaixada, regionalmente conhecida como depressão sertaneja. Nesse trabalho, foram identificadas diferentes formas de relevo granítico condicionadas, sobretudo por intempéries de subsuperfície, controladas por falhas e fraturas, e por remoção do regolito através da erosão superficial, além de eventos de esfoliação. Essas formas graníticas constituem peças fundamentais na compreensão da evolução paleoclimática do município de Irauçuba. Para a realização do presente trabalho foram usadas as seguintes metodologias: revisão bibliográfica, levantamento cartográfico e trabalho de campo.Palavras-chave: Feições graníticas; Superfícies de aplainamento; Erosão diferencial. ABSTRACTThe granitic rocks exhumation of Complexo Tamboril-Santa Quitéria, specifically, on the planing surface of Irauçuba county, Ceará, has revealed a great variety of geomorphological features that are justified by lithologic factors and evident Cenozoic climatic fluctuations, mainly, headed by mechanical morphogenesis, associated with dry climates. Residual reliefs like rocky massives, residual ridges, inselbergs and inselguebergs, slab stones and boulders in different degrees of development stand out in the middle of the lowered erosive surface, regionally known by “depressão sertaneja”. In this study, different forms of granite relief were identified, specially conditioned by subsurface erosion, controlled by geological faults and fractures, but also by regolith removal through surface erosion, plus exfoliation spheroidal events. These granitic features are fundamental in paleoclimatic evolution understanding of Irauçuba municipality. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work.Keywords: Granitic features; Planing surface; Differential erosion.RESUMENLa exhumación de rocas graníticas del Complejo tamboril-Santa Quitéria, específicamente en la superficie de aplanado del municipio de Irauçuba, Ceará, ha revelado una gran variedad de rasgos geomorfológicos que se justifican por factores litológicos y evidentes fluctuaciones climáticas cenozoicas, comandadas principalmente por morfogénesis mecánica, asociada a climas secos. Son relieves residuales como, macizos, crestas, Inselbergs, inselguebergs, losas y bloques saprolitizados (Boulders) en diferentes grados de desarrollo que sobresalen en medio de la superficie erosiva rebajada, regionalmente conocida como depresión sertaneja. En este trabajo, se identificaron diferentes formas de relieve granítico condicionadas, principalmente por intemperies de subsuperficie, controladas por fallas y fracturas, y por eliminación del regolito a través de la erosión superficial, además de eventos de exfoliación. Estas formas graníticas constituyen piezas fundamentales en la comprensión de la evolución paleoclimática del municipio de Irauçuba. Para la realización del presente trabajo se utilizaron las siguientes metodologías: revisión bibliográfica, levantamiento cartográfico y trabajo de campo.Palabras clave: Facciones graníticas; Superficies de aplanado; Erosión diferencial.

scholarly journals Late Quaternary Landscape Dynamics at the La Spezia Gulf (NW Italy): A Multi-Proxy Approach Reveals Environmental Variability within a Rocky Embayment

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 427
Author(s):  
Veronica Rossi ◽  
Alessandro Amorosi ◽  
Marco Marchesini ◽  
Silvia Marvelli ◽  
Andrea Cocchianella ◽  
...  
Keyword(s):  
Sea Level ◽  
Environmental Variability ◽  
Late Quaternary ◽  
Landscape Dynamics ◽  
Last Interglacial ◽  
Core Depth ◽  
Coastal Bay ◽  
Nw Italy ◽  
Global Sea Level ◽  
Geomorphological Features

The Gulf of La Spezia (GLS) in Northwest Italy is a rocky embayment with low fluvial influence facing the Mediterranean Sea. Past landscape dynamics were investigated through a multi-proxy, facies-based analysis down to a core depth of 30 m. The integration of quantitative ostracod, foraminifera, and pollen analyses, supported by radiocarbon ages, proved to be a powerful tool to unravel the late Quaternary palaeoenvironmental evolution and its forcing factors. The complex interplay between relative sea-level (RSL), climatic changes, and geomorphological features of the embayment drove four main evolution phases. A barrier–lagoon system developed in response to the rising RSL of the Late Pleistocene (likely the Last Interglacial). The establishment of glacial conditions then promoted the development of an alluvial environment, with generalised erosion of the underlying succession and subsequent accumulation of fluvial strata. The Holocene transgression (dated ca. 9000 cal year BP) caused GLS inundation and the formation of a low-confined lagoon basin, which rapidly turned into a coastal bay from ca. 8000 cal year BP onwards. This latter environmental change occurred in response to the last Holocene stage of global sea-level acceleration, which submerged a morphological relief currently forming a drowned barrier-island complex in the embayment.

scholarly journals Natural barriers: waterfall transit by small flying animals

2020 ◽  
Vol 7 (8) ◽  
pp. 201185
Author(s):  
Victor M. Ortega-Jimenez ◽  
Eva C. Herbst ◽  
Michelle S. Leung ◽  
Robert Dudley
Keyword(s):  
Complex Dynamics ◽  
Sister Group ◽  
The Body ◽  
Heterogeneous Structure ◽  
Flight Behaviour ◽  
Physical Constraints ◽  
Physical Barriers ◽  
Translational Speed ◽  
Geomorphological Features ◽  
Stroke Amplitude

Waterfalls are conspicuous geomorphological features with heterogeneous structure, complex dynamics and multiphase flows. Swifts, dippers and starlings are well-known to nest behind waterfalls, and have been reported to fly through them. For smaller fliers, by contrast, waterfalls seem to represent impenetrable barriers, but associated physical constraints and the kinematic responses of volant animals during transit are unknown. Here, we describe the flight behaviour of hummingbirds (the sister group to the swifts) and of various insect taxa as they fly through an artificial sheet waterfall. We additionally launched plastic balls at different speeds at the waterfall so as to assess the inertial dependence of sheet penetration. Hummingbirds were able to penetrate the waterfall with reductions in both their translational speed, and stroke amplitude. The body tilted more vertically and exhibited greater rotations in roll, pitch and yaw, along with increases in tail spread and pitch. The much smaller plastic balls and some flies moving at speeds greater than 2.3 m s −1 and 1.6 m s −1 , respectively, also overcame effects of surface tension and water momentum and passed through the waterfall; objects with lower momentum, by contrast, entered the sheet but then fell along with the moving water. Waterfalls can thus represent impenetrable physical barriers for small and slow animal fliers, and may also serve to exclude both predators and parasites from nests of some avian taxa.

Estrutura dos depósitos sedimentares quaternários da bacia hidrográfica do rio Santana, Miguel Pereira, Estado do Rio de Janeiro

1999 ◽  
Vol 22 ◽  
pp. 8-22 ◽  
Author(s):  
Claudio Valdetaro Madeira ◽  
Leonardo Borghi
Keyword(s):  
Alluvial Fans ◽  
Fluvial System ◽  
Soil Horizons ◽  
Hydrographic Basin ◽  
Sedimentary Deposits ◽  
River Bed ◽  
Anthropogenic Action ◽  
High Terrace ◽  
Crevasse Splay ◽  
Geomorphological Features

The present work deals with stratigraphy, sedimentology and geomorphology of Quaternary sedimentary deposits of Santana river hydrographic basin. through facies and arquitectural elements descriptions. Based on five arquitectural elements characterized by ten lithofacies the following structural and depositional evolutions were scheduled: 1) formation of thick soil horizons over the basement; 2) deposition of several alluvial fans on the soils (lithofacies Gm and Fm, element E); 3) above an unconformity we can recognize a fluvial system, characterized by a non well drainage floodplain. This floodplain is overlaid by high-sinuosity channels (lithofacies Sp and St, element C) genetically related to other floodplain (lithofacies Fl and Fsc, element A) where the interfigering with crevasse splay deposits (lithofacies Sh, Sl, and Sp, element B) is ususal; 4) an erosional phase suceed by a new depositional phase characterized by low-sinuosity channels (lithofacies Gp, Gt, Sp, St, and Sh, element D). Nowadays anthropogenic action produces a new erosional phase. The geomorphological features recognized were scheduled: 1) the present floodplain 1.5m above the river bed; 2) the low terrace ( named T2) 5m above the river bed and its deposits is related to element D; 3) the high terrace ( named T1) 11m above the river bed and its deposits is related to elements A, B, C and E.

A Geomorphological Approach to Geodiversity and Geotourism in Uttarakhand Himalaya, India: A Pilot Survey 

2021 ◽  
Author(s):  
Anita Pande
Keyword(s):  
The State ◽  
Point Of View ◽  
North India ◽  
Tethys Sea ◽  
Geomorphological Heritage ◽  
The World ◽  
Tectonic Boundaries ◽  
Geomorphological Features ◽  
Tectonic Origin ◽  
Uttarakhand Himalaya

<p>Himalaya is the greatest heritage of India. The objective of this paper is to present a view of the geomorphological heritage of the Himalaya.Uttarakhand<strong> </strong>state (77°35’5”-81°2’25” E and 28°43’45”-31°8’18’’N, Area: 53,066 sq.km.)<strong> </strong>lies almost wholly within the realm of the Himalaya and is a distinct geographical entity. The state is a land of vast geological and topographic diversities and a realm with rich geo-wealth and geoheritage. Geological and geomorphological features occurring in different parts of Uttarakhand Himalaya are part of the natural assets and are precious state heritage (geoheritage), worthy of conservation. Apart from rock monuments and fossil parks, geomorphological features or geomorphosites have great potential to exert a pull on tourists. These sites have noteworthy impact on the geoscience education and research. Geotourism is growing rapidly all over the world and Himalaya region is no exception to this. To promote geotourism in the Himalayan State of Uttarakhand, comprehensive information about geomorphosites should be made available to the tourists by way of websites. For this, first a peer-reviewed state inventory of geomorphosites and their classification, mapping and assessment is required. Geodiversity in Uttarakhand State can best be understood in the form of the rise of Himalayan mountains from the bed of Tethys Sea which gave rise to four distinct tectonic units largely varying in lithology and structure. The relief was fragmented into four major morphosculptural units which signify the mountainous part of the state: viz. i. the Tethys zone or the Trans-Himalaya ii. the Greater Himalaya iii. the Lesser Himalaya and iv. the Siwalik. Apart from this mountainous region of the State, there is  outlying region of the state, which incompasses : iv. Bhabhar and Tarai (a sub-montane tract) - a landscape feature along the foothills, v. Dun Valleys – valleys of tectonic origin and vi. Plains of North India - the lowest part in Uttarakhand with an altitude of 200 m. These geological units recognised on the basis of evolutionary history, stratigraphic sequences and component rock units and reveal identical topographic and climatic characteristics. These units are separated by various tectonic boundaries. Apart from geodiversity, the geomorphological diversity can be assessed in the form of towering snow peaks, awe-inspiring horned peaks with natural grandeur, widely distributed stretches of wide and fertile valleys, valleys of tectonic origin-canoe shaped longitudinal valleys, lofty snow capped peak surrounded by several small and big snowfields, glaciers and lakes, mountain passes and  elevated zones packed in a series of multi-level distinctive waterfalls. Thus, being the youngest mountain of the world, this Himalayan State has geotouristic potential from the point of view of its geomorphological heritage.</p><p><strong> </strong><strong>Keywords: </strong>Himalaya<strong>, </strong>geodiversity , geomorphological heritage, geomorphosites, geotourism.  </p>

scholarly journals Aqra Anticline: A Growing Structure in the Iraqi Kurdistan Region

2019 ◽  
Vol 7 (2) ◽  
pp. 27-33
Author(s):  
Ala A. Ghafur ◽  
Varoujan K. Sissakian ◽  
Hawkar A. Abdulhaq ◽  
Hassan O. Omar
Keyword(s):  
Satellite Images ◽  
Structural Features ◽  
Alluvial Fans ◽  
Lateral Growth ◽  
Kurdistan Region ◽  
Iraqi Kurdistan ◽  
Geomorphological Features

Aqra Anticline is a double plunging anticline, oriented NW–SE with a steep southwestern limb and even overturned. Geomorphological features are interpreted using satellite images, as a result, it was found that the anticline shows clear geomorphological and structural features which indicate the lateral growth of the anticline. Among those features are water gaps, wind gaps, forked-shaped valleys, curved valleys, inclined valleys and dislocated and abandoned alluvial fans. Some of the vague interpreted features were checked and confirmed in the field.

Sign in / Sign up

Export Citation Format

Share Document