scholarly journals SEDIMENTATION, TRANSPORT UND EROSION AN DER NORDKÜSTE KOLUMBIENS ZWISCHEN BARRANQUILLA UND DER SIERRA NEVADA DE SANTA MARTA

2016 ◽  
Vol 7 ◽  
Author(s):  
Von Axel Frhr ◽  
Von Erffa
Keyword(s):  
Sierra Nevada ◽  
River Mouth ◽  
Heavy Minerals ◽  
Morphological Evidence ◽  
Second Phase ◽  
Morphological Alterations ◽  
Longshore Drift ◽  
Geological Past ◽  
North Eastern ◽  
Magdalena River

The coast of Northern Colombia between Barranquilla and the Sierra Nevada de Santa Marta has been subject to swift morphological alterations in the near geological past. The Magdalena River mouth into the Caribbean Sea is actually in the western end of the region and has formed deltas in three phases during the recent Quaternary. The two older ones were destroyed by erosion ad can only be detected by submarine morphology. The second phase is represented by a delta, that reached its widest dimensions approximately 2.400 years ago. The then starting destruction continues untill today and is not yet finished. The recent mouth foresets the youngest delta of the Magdalena River. A westbound longshore current along the not always even shoreline is produced by north-eastern tradewinds. This current transports the eroded sediments of the second oldest delta to the mouth of the Magdalena River. Part of them helps to build its new delta, and part of them glides through submarine cañons to the deep sea. Besides the morphological evidence, sedimentary analysis of the shore sands shows: 1. a longshore drift of sediments from east to west. 2. a change in the balance of energy: sedimentation in the east; erosion in the west (placers of heavy minerals). The very important highway from Barranquilla to Santa Marta ist thus endangered by erosion in the near future. 3. the sources of the upper sedimentlayers in the shore area: in the oldest delta their provenance is the Sierra Nevada de Santa Marta; in the younger deltas the area of affluents of the Magdalena River.

scholarly journals Development of the Narva-Jõesuu beach, mineral composition of beach deposits and destruction of the pier, southeastern coast of the Gulf of Finland

2019 ◽  
Vol 11 (1) ◽  
pp. 961-968
Author(s):  
Johanna-Iisebel Järvelill
Keyword(s):  
Mineral Composition ◽  
Mineral Content ◽  
Sandy Beach ◽  
Heavy Minerals ◽  
Gulf Of Finland ◽  
Immersion Method ◽  
Southeastern Coast ◽  
Longshore Drift ◽  
Favorable Conditions ◽  
The Gulf Of Finland

Abstract Narva-Jõesuu lies at the eastern southeastern coast of the Gulf of Finland, at the Estonian and Russian border. The beach is influenced by heavy winds, waves and drift ice attacks, which are seriously changing the beach. It is the longest sandy beach in Estonia and longshore drift on this beach has induced favorable conditions for the separation of heavy minerals. The aims of the study were to describe the development of the coast, discuss the influence of the destructed pier, and to identify the mineral composition of beach sands. The dynamics of the coast were mainly through comparison with older topographic maps (from the beginning of the 20th century). For mineral analysis the immersion method was applied. The heavy mineral content was found to increase from east to west. The pier was built in Narva-Jõesuu in 1987/88 for protecting the coast, but it is now broken. Consequently, storms are crashing against the coast and erosion of the sandy shore has started. Therefore, the pier should be restored to avoid further beach destruction.

scholarly journals A new species of the catfish genus Cordylancistrus (Siluriformes, Loricariidae) from the Sierra Nevada de Santa Marta, Colombia

Zootaxa ◽  
2017 ◽  
Vol 4329 (3) ◽  
pp. 256
Author(s):  
FRANCISCO PROVENZANO R. ◽  
NADIA MILANI ◽  
CARLOS ARDILA R.
Keyword(s):  
New Species ◽  
South America ◽  
Sierra Nevada ◽  
Related Species ◽  
Caribbean Sea ◽  
Geological History ◽  
The Andes ◽  
History Of ◽  
Magdalena River ◽  
A New Species

As a part of an assessment of loricariid catfishes inhabiting the Andes of Colombia, specimens belonging to an interesting new species were identified. The new species is described herein, and it is tentatively included in the genus Cordylancistrus. The new species can be easily distinguished among its congeners by the presence of a unique diagnostic character: a fleshy keel or excrescence, black or dark brown, over the posterior tip of supraoccipital. Specimens of the new species were captured in rivers of the Sierra Nevada de Santa Marta and the Sierra de Perijá that drain to the Magdalena River Basin and Caribbean Sea. The occurrence of one species of Cordylancistrus in the Sierra Nevada de Santa Marta could have interesting biogeographic implications for hypotheses related to the geological history of northwestern corner of South America or to the dispersal or vicariance models used to explain biogeographical patterns of related species in Colombia. 

Revision of the status of Saurolophus (Hadrosauridae) from California, USA

2010 ◽  
Vol 47 (11) ◽  
pp. 1417-1426 ◽  
Author(s):  
Phil R. Bell ◽  
David C. Evans
Keyword(s):  
Phylogenetic Analysis ◽  
Sierra Nevada ◽  
Sister Taxon ◽  
Morphological Evidence ◽  
Magmatic Arc ◽  
The Status ◽  
Previous Assignment ◽  
Geographic Setting

The occurrence of Saurolophus from the Moreno Formation (late Maastrichtian) of California is investigated and an incomplete, poorly preserved, skull (LACM/CIT 2852) is described. The skull lacks the braincase (including the frontals) and much of the nasals, and the preserved portions are crushed or plastically deformed, which makes anatomical interpretations difficult. A preserved midline fragment of the conjoined nasals suggests that it lacked a gryposaur-like “Roman nose”, but the nature of the crest, if present, is impossible to determine with certainty. A phylogenetic analysis places this specimen as either the sister taxon of Saurolophus or as the sister taxon to a clade comprising Edmontosaurus and Anatotitan . There is no compelling morphological evidence to support the previous assignment of LACM/CIT 2852 to Saurolophus rather than to Edmontosaurus, and its poor preservation prevents positive assignment to any taxon below Hadrosaurinae indet. Given its geographic setting and morphological uncertainties, it is also possible that this specimen represents a separate taxon, but more material is needed to clarify the identity of the Moreno hadrosaurine. LACM/CIT 2852 does, however, provide evidence that Maastrichtian hadrosaurines ranged west of the Sierra Nevada magmatic arc, in an area where dinosaur diversity is poorly known.

Molecular taxonomic reassessment of the Cloud Forest’s Bolitoglossa salamanders (Caudata: Plethodontidae) from Cordillera de Mérida (Mérida state, Venezuela)

Zootaxa ◽  
2012 ◽  
Vol 3356 (1) ◽  
pp. 47 ◽  
Author(s):  
GUSTAVO FERMIN ◽  
JAVIER GARCÍA-GUTIÉRREZ ◽  
MOISÉS ESCALONA ◽  
ANDRÉS MORA ◽  
AMELIA DÍAZ
Keyword(s):  
16S Rrna ◽  
Sierra Nevada ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Morphological Evidence ◽  
Rrna Gene ◽  
Putative Species ◽  
Salamander Species ◽  
The 16S Rrna Gene ◽  
Tissue Digestion

Salamanders found at different localities nearby Mérida city, Venezuela, are thus far reported as Bolitoglossa orestes or B.spongai. However, morphological ambiguities among individuals from several populations of both putative species, besidestheir reported disparate geographical distributions, prompted us to clarify the specific identity of these bolitoglossines throughthe sequence analysis of their corresponding 16S rRNA genes. Seventeen specimens belonging to the vertebrates collection ofUniversidad de Los Andes (CVULA), collected at separated cloud forests in Sierra La Culata (San Eusebio, Macho Capaz andSan Javier del Valle) and Sierra Nevada de Mérida (La Mucuy), were used to extract DNA upon tissue digestion. Sequenceanalysis of the 16S rRNA gene supports a biogeographical scenario where, so far, there is only one salamander species for eachsierra: B. orestes, which is widely distributed in Sierra La Culata, and a so far undescribed species of a Venezuelan bolitogloss-ine apparently restricted to Sierra Nevada de Mérida. Based on our molecular results and an examination of morphological evidence, B. spongai should be considered a synonym of B. orestes.

Siltation on a highly regulated estuarine system: The Magdalena River mouth case (Northwestern South America)

2020 ◽  
Vol 245 ◽  
pp. 107020
Author(s):  
Juan C. Restrepo ◽  
Andrés Orejarena-Rondón ◽  
Carolina Consuegra ◽  
Javier Pérez ◽  
Humberto Llinas ◽  
...  
Keyword(s):  
South America ◽  
River Mouth ◽  
Estuarine System ◽  
Magdalena River

scholarly journals Post-Collapse Evolution of a Rapid Landslide from Sequential Analysis with FE and SPH-Based Models

Geosciences ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 364
Author(s):  
Lorenzo Brezzi ◽  
Edoardo Carraro ◽  
Davide Pasa ◽  
Giordano Teza ◽  
Simonetta Cola ◽  
...  
Keyword(s):  
Sequential Analysis ◽  
Reliable Estimate ◽  
Second Phase ◽  
3D Fem ◽  
Soil Deposits ◽  
North Eastern ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Landslide Evolution ◽  
Smoothed Particle

Propagation models can study the runout and deposit of potential flow-like landslides only if a reliable estimate of the shape and size of the volumes involved in the phenomenon is available. This aspect becomes critical when a collapse has not yet occurred and the estimation of the unstable volume is not uniquely predictable. This work proposes a strategy to overcome this problem, using two established analysis methods in sequence; first, a Strength Reduction Method (SRM)-based 3D FEM allows the estimate of the instable volume; then, this data becomes an input for a Smoothed Particle Hydrodynamics (SPH)-based model. This strategy is applied to predict the possible evolution of Sant’Andrea landslide (North-Eastern Italian Alps). Such a complex landslide, which affects anhydrite–gypsum rocks and is strongly subject to rainfall triggering, can be considered as a prototype for the use of this procedure. In this case, the FEM–SRM model is adopted, which calibrates using mapping, monitoring, geophysical and geotechnical data to estimate the volume involved in the potential detachment. This volume is subsequently used as the input of the SPH model. In this second phase, a sensitivity analysis is also performed to complete the evaluation of the most reliable final soil deposits. The performed analyses allow a satisfactory prediction of the post-collapse landslide evolution, delivering a reliable estimate of the volumes involved in the collapse and a reliable forecast of the landslide runout.

Paleogeographic implications of a multi-parameter Paleogene provenance dataset (Transylvanian Basin, Romania)

2021 ◽  
Vol 91 (6) ◽  
pp. 551-570
Author(s):  
Gabriella Obbágy ◽  
István Dunkl ◽  
Sándor Józsa ◽  
Lóránd Silye ◽  
Róbert Arató ◽  
...  
Keyword(s):  
Sedimentary Environment ◽  
Volcanic Rocks ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Second Phase ◽  
Provenance Analysis ◽  
Drainage Patterns ◽  
Mineral Associations ◽  
Recent Developments ◽  
Felsic Volcanic

ABSTRACT Recent developments in geoanalytics have led to the rapidly increasing potential of sedimentary provenance analysis in paleogeographic reconstructions. Here we combine standard methods (petrography, zircon U-Pb geochronology, optical heavy-mineral identification) with modern techniques such as automated Raman-spectroscopic identification of heavy minerals and detrital apatite and titanite U-Pb geochronology. The resulting multi-parameter dataset enables the reconstruction of tectonic and paleogeographic environments to an as-yet unprecedented accuracy in space and time. The Paleogene siliciclastic formations of our study area, the Transylvanian Basin, represent an intensely changing sedimentary environment comprising three transgressive–regressive cycles on a simultaneously moving and rotating tectonic plate. We identified six major source components of the Paleogene sediments and outlined the paleo-drainage patterns for the three cycles, respectively. According to our data these components include: 1) pre-Variscan basement units of the nappes, 2) Variscan granitoids, 3) Permo-Triassic felsic volcanic rocks, 4) Jurassic ophiolites, 5) Upper Cretaceous granodiorites, and 6) Priabonian to Rupelian (37–30 Ma) intermediate magmatites, the latter representing newly recognized formations in the region. Abrupt paleographic changes can be directly deduced from the obtained dataset. The first phase of the Paleogene siliciclastic sequence is composed of mostly Southern Carpathian–derived sediments, to which Jurassic ophiolite detritus of the Apuseni Mts. was added during the second phase, while the siliciclastic material of the third phase represents mainly recycled material from the second phase. According to the detected diagnostic heavy-mineral associations, U-Pb age components and the positions of the potential source areas a set of provenance maps are presented.

The genera Chiastocaulon, Cryptoplagiochila and Pedinophyllum (Plagiochilaceae) in Australia

2016 ◽  
Vol 29 (5) ◽  
pp. 358 ◽  
Author(s):  
Matt A. M. Renner ◽  
Margaret M. Heslewood ◽  
Simon D. F. Patzak ◽  
Alfons Schäfer-Verwimp ◽  
Jochen Heinrichs
Keyword(s):  
New Zealand ◽  
New Records ◽  
The Other ◽  
Morphological Data ◽  
Morphological Evidence ◽  
Australian Species ◽  
North Eastern ◽  
Australian Flora ◽  
Papua New Guinean ◽  
Single Locality

Molecular and morphological data support the recognition of seven species of Chiastocaulon in Australia, of which four, namely C. braunianum and C. geminifolium comb. nov. from tropical north-eastern Queensland and C. proliferum and C. flamabilis sp. nov. from Tasmania (and New Zealand), represent new records. The other three species accepted for Australia are C. biserialis, C. dendroides and C. oppositum. Chiastocaulon conjugatum is excluded from the Australian flora, because previous Australian records are based on misidentifications of C. braunianum and Plagiochila retrospectans. Pedinophyllum monoicum, reported for Australia from a single locality in Victoria, is excluded from the Australian flora because all credible records are based on misidentifications of Syzygiella tasmanica. The Papua New Guinean Chiastocaulon takakii comb. nov. is reinstated from synonymy under C. dendroides on the basis of morphological evidence. Descriptions and illustrations of all Australian species, and dichotomous keys to species of the Chiastocaulon lineage in Australia and New Zealand, are provided.

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