scholarly journals Hydrogeological dissimilarity of geodynamically different terranes

2021 ◽  
Vol 44 (2) ◽  
pp. 134-140
Author(s):  
V. E. Glotov
Keyword(s):  
Continental Margin ◽  
Sandy Loam ◽  
Active Continental Margin ◽  
Passive Continental Margin ◽  
Coarse Grained ◽  
Active Margin ◽  
Water Abundance ◽  
Fine Grained ◽  
Weathering Processes

The article presents and analyzes the data on ground waters of active (suprapermafrost) and hindered (subpermafrost) water exchange of geodynamically different terrains in order to prove the hydrogeological importance of their historical and tectonic characteristics. On the example of Trans-Polar Chukotka it is shown that, under suprapermafrost conditions, the ubiquitous eluvial-deluvial nappes are the most water-abundant on the terrane – a fragment of the passive continental margin, whereas they are the least water-abundant on the terrains of the active margin. Hydrogeological situation changes under subpermafrost conditions: more permeable and water-retaining rocks compose the terranes of the active margin. These differences are associated with the level of rock tectonic decompaction and, accordingly, with different intensity of weathering processes in the terrane rocks of different geodynamic origin in suprapermafrost and subpermafrost conditions. The hypergenesis zone on the terranes of the passive continental margin features coarse-grained rock weathering products accumulated in relatively calm geological and historical environments, the aggregate is sandy. The terranes of the active margin, which underwent long-term subvertical and subhorizontal displacements contain more fine-grained weathering products; the aggregate includes sandy loam and clay sand. Since the permafrost strata in both Trans-Polar Chukotka and Eastern Siberia is greater than the depth of hypergene transformations, the terranes of the active continental margin, the rocks of which were impacted by tectonic decompaction processes, mainly of a strike-slip and thrust nature, feature greater water abundance in subpermafrost conditions.

scholarly journals AS BACIAS PROTEROZÓICAS DO ESPINHAÇO E SÃO FRANCISCO EM MINAS GERAIS: UMA ABORDAGEM DO PONTO DE VISTA DA ESTRATIGRAFIA DE SEQUÊNCIAS

1998 ◽  
Vol 6 (1) ◽  
Author(s):  
Rogério Rodrigues da Silva
Keyword(s):  
Continental Margin ◽  
Source Area ◽  
Minas Gerais ◽  
Passive Continental Margin ◽  
Normal Faults ◽  
Depositional Sequences ◽  
Fine Grained ◽  
Listric Fault ◽  
Depositional Patterns ◽  
Brasiliano Orogeny

This work deals with Sequence Stratigraphy concepts applied to the Proterozoic record of the SãoFrancisco Craton in Minas Gerais, southeast Brazil. The cratonic cover is characterized by eight sequenceboundaries (unconformity and/or correlative conformity), which subdivide the Proterozoic stratigraphyinto seven depositional sequences. These sequences initially filled an intracratonic rift basin (the EspinhaçoBasin), which evolved into a passive continental margin (the São Francisco Basin). The Espinhaço Basinwas filled by six stacked depositional sequences. Their sequence boundary unconformities are indicative oftaphrogenic periods, when tectonic displacements were mainly accomodated along a master listric fault,but also along synthetic and antithetic subsidiary normal faults. The unconformities are covered by coarsealluvial conglomerates, deposited by the combined effects of source area uplift and depocenter subsidence.The depositional sequences of the Espinhaço Basin show impressive cyclical depositional patterns. Theyusually show the unconformities and the basal conglomerates covered by shallow-marine transgressivesediments. The São Francisco Basin, a passive continental margin, was developed at approximately 0.9 Ga.Coevally, a continental glatiation occurred over the craton, which produced a relative fall in the sea level,erosion and hence unconformity development. During that time, the basin was characterized by the depositionof tillites on the proximal reachs and turbidites on the distal portions. A transgressive phase followed theglaciation and was marked by the deposition of fine-grained sediments (lutites) and carbonatic rocksoverlaying the cratonic areas. Around 0.6 Ga, during the Brasiliano Orogeny, the Espinhaço and São FranciscoBasins were inverted.

scholarly journals Multimodal Transformer Networks for Pedestrian Trajectory Prediction

2021 ◽  
Author(s):  
Ziyi Yin ◽  
Ruijin Liu ◽  
Zhiliang Xiong ◽  
Zejian Yuan
Keyword(s):  
Optical Flow ◽  
Temporal Variations ◽  
Coarse Grained ◽  
Vehicle Speed ◽  
Temporal Consistency ◽  
Moving Vehicle ◽  
Dynamic Motion ◽  
Fine Grained ◽  
High Dynamics

We consider the problem of forecasting the future locations of pedestrians in an ego-centric view of a moving vehicle. Current CNNs or RNNs are flawed in capturing the high dynamics of motion between pedestrians and the ego-vehicle, and suffer from the massive parameter usages due to the inefficiency of learning long-term temporal dependencies. To address these issues, we propose an efficient multimodal transformer network that aggregates the trajectory and ego-vehicle speed variations at a coarse granularity and interacts with the optical flow in a fine-grained level to fill the vacancy of highly dynamic motion. Specifically, a coarse-grained fusion stage fuses the information between trajectory and ego-vehicle speed modalities to capture the general temporal consistency. Meanwhile, a fine-grained fusion stage merges the optical flow in the center area and pedestrian area, which compensates the highly dynamic motion of ego-vehicle and target pedestrian. Besides, the whole network is only attention-based that can efficiently model long-term sequences for better capturing the temporal variations. Our multimodal transformer is validated on the PIE and JAAD datasets and achieves state-of-the-art performance with the most light-weight model size. The codes are available at https://github.com/ericyinyzy/MTN_trajectory.

Studies with the intraruminal selenium pellet. 2. The effect of grain size of selenium on the functional life of pellets in sheep

1981 ◽  
Vol 32 (6) ◽  
pp. 935 ◽  
Author(s):  
DR Hudson ◽  
RA Hunter ◽  
DW Peter
Keyword(s):  
Grain Size ◽  
Progressive Increase ◽  
Coarse Grained ◽  
Elemental Selenium ◽  
Average Composition ◽  
Plasma Selenium ◽  
Iron Selenide ◽  
Fine Grained ◽  
Grain Sizes

Grain size of elemental selenium is a major factor controlling the long-term effectiveness of intraruminal selenium pellets. Microscope studies of polished sections of new and used selenium pellets showed that two commercially manufactured pellets contained selenium with average grain sizes about 4 and 40 �m respectively. Plasma selenium concentrations in sheep treated with pellets containing the coarse-grained selenium were maintained at higher levels over longer periods of time than those measured for sheep treated with pellets with fine-grained selenium. Pellets removed from sheep after 2, 4, 8, 16 and 28 days showed a progressive increase in the degree of alteration of selenium to a compound of average composition (g/100 g) iron, 33.7; selenium, 51.3 ; oxygen, 15.0. After 28 days only a small percentage of elemental selenium remained in pellets with fine-grained selenium, whereas about 50% remained in pellets with coarse-grained selenium. CSIRO prototype pellets, for which long-term effectiveness had been established, also contained coarse-grained selenium, and remnants of selenium were found in pellets that had been in sheep for periods up to 3 years. Selenium, administered in gelatin capsules or as sachets containing glass-selenium mixtures, was stable under the pH-Eh conditions of the rumen, but was rendered unstable in selenium pellets or iron-selenium mixtures by the presence of iron. It is probable that the most rapid release of selenium to the sheep occurs as a result of a chemical reaction involving the oxidation of iron and concomitant alteration of elemental selenium to iron selenide.

Deformation and reaction fabrics in eclogites from the Western Gneiss Region (Norway) - evidence of dehydration reactions attributed to episodic deformation

2021 ◽  
Author(s):  
Claudia A. Trepmann ◽  
Ane K. Engvik ◽  
Erick G. Prince Gutierrez
Keyword(s):  
Inner Core ◽  
White Mica ◽  
Coarse Grained ◽  
Dislocation Creep ◽  
Western Gneiss Region ◽  
Garnet Porphyroblasts ◽  
Boundary Area ◽  
Fine Grained ◽  
Dehydration Reactions

<p>The eclogites from Vårdalneset, Western Gneiss Region, Norway, show an exceptional large variety of reaction and deformation microfabrics that document the processes and conditions during burial and exhumation. Coarse grained eclogites comprise about 35% omphacite, 25% garnet and 20% amphibole with various amounts of white mica, zoisite, kyanite, rutile, zircon and pyrite. Their fabric is characterized by few mm long and several hundred µm wide amphibole and omphacite grains aligned in the foliation plane with zoned garnet porphyroblasts up to several mm in diameter. In contrast, finer-grained mylonitic eclogites with grain diameters of few hundred µm comprise systematically higher amounts of garnet (45%) and omphacite (35%) and generally less amphibole (< 5%) but similar amounts of zoisite, white mica, rutile and quartz. In the coarse-grained eclogite, amphibole shows evidence of dislocation creep as indicated by undulatory extinction, subgrains and recrystallized grains in necks of boudinaged coarse amphibole layers as well as in contact to garnet. The large garnet porphyroblasts generally show a complex zonation with an inclusion-rich Fe-poor and Mg-rich inner core surrounded by a zone with Fe- and Ca-rich patches and a broad Mg-rich, Ca- and Fe-poor rim. Only at contact to coarse amphibole an additional, a few tens of µm thin serrated rim further enriched in Mg can occur. At the direct contact to such serrated Mg-rich rims, amphibole is partly replaced by a fine-grained quartz-kyanite ± rutile aggregate, indicating dehydration reactions of amphibole. Quartz - kyanite ± rutile aggregates are surrounding garnet also in contact to omphacite, zoisite and to other garnet crystals. The microstructures suggest that deformation and dehydration of amphibole are coupled and played an important role during deformation of the eclogites finally leading to the mylonitic eclogites with higher amounts of garnet and omphacite. Deformation is suggested to have triggered the dehydration reaction by a slight and local increase in temperature. Furthermore, deformation provided additional pathways for the escaping fluids along the increased grain and phase boundary area, as indicated by commonly present quartz within interstitials between recrystallized amphibole grains. In all samples, few µm wide amphibole rims replacing garnets document restricted rehydration-reactions at a later stage. The large variety of the deformation and reaction microfabrics exemplarily show that both deformation and metamorphic reactions did not proceed at long-term continuous conditions, but that both are coupled and occurred episodically.</p>

A revised lithostratigraphy of the Lower–Middle Ordovician Beekmantown Group, St. Lawrence Lowlands, Quebec and Ontario

1992 ◽  
Vol 29 (12) ◽  
pp. 2677-2694 ◽  
Author(s):  
Lawrence Bernstein
Keyword(s):  
Continental Margin ◽  
Carbonate Platform ◽  
Trace Fossils ◽  
Coarse Grained ◽  
Middle Ordovician ◽  
Fine Grained ◽  
Quartz Arenite ◽  
Taconic Orogeny ◽  
Reference Section

The Lower – lower Middle Ordovician Beekmantown Group of the St. Lawrence Lowlands is a variably thick pertitidal succession of dolostone, limestone, quartzose carbonate, and subordinate siltstone and shale that is gradationally bound by the Potsdam Group below and unconformably to conformably by the Chazy Group above. It is here considered to include three regionally extensive formations, a basal Theresa, a middle Beauharnois, and an upper, redefined Carillon. A principal reference section is established in the subsurface. The Theresa Formation is a transgressive succession, above Potsdam Group siliciclastics and below Beauharnois Formation carbonates. It is dominated by quartz arenite and quartzose dolostone; skeletal fossils are rare (usually gastropods), whereas trace fossils are abundant. The Beauharnois Formation is divided into two members, a basal Ogdensburg and an upper Huntingdon. The Ogdensburg Member is sandy, especially in its lower part, and relatively more fossiliferous than the Huntingdon Member. Both members include fossiliferous and nonfossiliferous, stromatolitic and oolitic, coarse-grained dolostone and subordinate limestone and reflect the development of a relatively wide peritidal carbonate platform. The Carillon Formation is a widespread unit that marks the onset of Middle Ordovician Taconic orogeny at the continental margin. It consists mostly of cyclic packages of laminated and burrowed, fine-grained dolostone and limestone, and as well siltstone and shale. Thin fossiliferous beds are dispersed in its upper part.

scholarly journals Dynamics and age of formation of the Seram-Ambon ophiolites (Central Indonesia)

2003 ◽  
Vol 174 (6) ◽  
pp. 529-543 ◽  
Author(s):  
Christophe Monnier ◽  
Jacques Girardeau ◽  
Hariady Permana ◽  
Jean-Pierre Rehault ◽  
Hervé Bellon ◽  
...  
Keyword(s):  
Continental Crust ◽  
Continental Margin ◽  
Passive Continental Margin ◽  
Early Miocene ◽  
Geochemical Data ◽  
Active Margin ◽  
Short Span ◽  
Group 2 ◽  
Type 3

Abstract The Seram-Ambon ophiolitic series comprise peridotites, websterites, gabbros and lavas. Petro-geochemical data show that the peridotites are weakly depleted rocks, except for the rare Cpx-free harzburgites. They underwent a sub-solidus metamorphic re-equilibration in the plagioclase field. The associated websterites and gabbros display various chemical features, allowing to define 3 types of websterites and 2 groups of gabbros. They have mostly BAB characteristics (presence of negative anomalies in Nb, Zr, Ti and Y), except the group 2 gabbros which have N-MORB features and the type 3 websterites which bear adakitic affinities. Lavas also display a variety of compositions, including high-Mg IAT and Mg-rich BABB with sub-alkaline affinities. Both IAT and BABB display high Th/Nb ratios which support an origin close to a continental crust environment. Our 20 to 15 Ma 40K/40Ar ages calculated for the BABB and 15-9 Ma for the IAT show that the basin and arc formed in a very short span of time, before their obduction 9–7 Ma ago [Linthout et al., 1997]. Considering the paleogeographic situation in the Miocene [Haile, 1979 ; Haile, 1981] and our data, we propose that the Seram-Ambon ophiolites formed during the early Miocene in a small, short-lived (10 Ma), transtensive basin bordered on its east by an active margin and on its western part by a passive continental margin over which it was later obducted towards the SW direction.

Petrology of alkali wehrlite sills in the Oman Mountains

1984 ◽  
Vol 48 (346) ◽  
pp. 13-20 ◽  
Author(s):  
S. J. Lippard
Keyword(s):  
Continental Margin ◽  
Tectonic Setting ◽  
Light Element ◽  
Parent Magma ◽  
Coarse Grained ◽  
Thrust Belt ◽  
Fine Grained ◽  
Oman Mountains ◽  
Incompatible Elements ◽  
Rich Liquid

AbstractAlkaline mafic sills of Jurassic to Cretaceous age in the Oman Mountains have coarse-grained wehrlite centres composed of olivine and zoned diopside-titanaugite with large interstitial poikilitic titanian hornblendes and titanian barian phlogopites and biotites which appear to have crystallized from a trapped, intergranular, volatile-rich liquid. The fine-grained chilled margins of the sills are olivine-poor and composed largely of titanaugite, kaersutite, sphene, and interstitial altered plagioclase. The rocks have high contents of incompatible elements (Ti, P, Sr, Ba, Zr, Nb, and others) and steeply inclined, light element enriched, REE patterns. The parent magma is estimated to have been a hydrous alkali picrite with c. 12% MgO from which the wehrlite formed by olivine accumulation. The unusual tectonic setting of the sills, in a Mesozoic continental margin sequence emplaced in an Alpine thrust belt, is noted.

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