scholarly journals Integrated Geochemical Assessment of Soils and Stream Sediments to Evaluate Source-Sink Relationships and Background Variations in the Parauapebas River Basin, Eastern Amazon

Soil Systems ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 21
Author(s):  
Gabriel Negreiros Salomão ◽  
Danielle de Lima Farias ◽  
Prafulla Kumar Sahoo ◽  
Roberto Dall’Agnol ◽  
Dibyendu Sarkar
Keyword(s):  
River Basin ◽  
Regional Scale ◽  
Stream Sediments ◽  
Geochemical Data ◽  
Geochemical Background ◽  
Data Set ◽  
The North ◽  
Quality Guidelines ◽  
Guideline Values ◽  
Environmental Agencies

This study aims to handle an integrated evaluation of soil and stream sediment geochemical data to evaluate source apportionment and to establish geochemical threshold variations for Fe, Al, and 20 selected Potentially Toxic Elements (PTE) in the Parauapebas River Basin (PB), Eastern Amazon. The data set used in this study is from the Itacaiúnas Geochemical Mapping and Background Project (ItacGMBP), which collected 364 surface soil (0–10 cm) samples and 189 stream sediments samples in the entire PB. The <0.177 mm fraction of these samples were analyzed for 51 elements by ICP-MS and ICP-AES, following an aqua regia digestion. The geochemical maps of many elements revealed substantial differences between the north (NPB) and the south (SPB) of PB, mainly due to the geological setting. The new statistically derived threshold values of the NPB and SPB regions were compared to the threshold of the whole PB, reported in previous studies, and to quality guidelines proposed by Brazilian environmental agencies. The natural variation of geochemical background in soils and stream sediments of PB should be considered prior to defining new guideline values. At the regional scale, the local anomalies are mostly influenced by the predominant lithology rather than any anthropogenic impact.

scholarly journals MODIS observed increase in duration and spatial extent of sediment plumes in Greenland fjords

2014 ◽  
Vol 8 (4) ◽  
pp. 1161-1176 ◽  
Author(s):  
B. Hudson ◽  
I. Overeem ◽  
D. McGrath ◽  
J. P. M. Syvitski ◽  
A. Mikkelsen ◽  
...  
Keyword(s):  
North Atlantic Ocean ◽  
Regional Scale ◽  
Greenland Ice Sheet ◽  
Sediment Concentration ◽  
Retrieval Algorithm ◽  
Freshwater Flux ◽  
River Plumes ◽  
Data Set ◽  
In Situ Data ◽  
The North

Abstract. The freshwater flux from the Greenland Ice Sheet (GrIS) to the North Atlantic Ocean carries extensive but poorly documented volumes of sediment. We develop a suspended sediment concentration (SSC) retrieval algorithm using a large Greenland specific in situ data set. This algorithm is applied to all cloud-free NASA Moderate Resolution Imaging Spectrometer (MODIS) Terra images from 2000 to 2012 to monitor SSC dynamics at six river plumes in three fjords in southwest Greenland. Melt-season mean plume SSC increased at all but one site, although these trends were primarily not statistically significant. Zones of sediment concentration > 50 mg L−1 expanded in three river plumes, with potential consequences for biological productivity. The high SSC cores of sediment plumes ( > 250 mg L−1 expanded in one-third of study locations. At a regional scale, higher volumes of runoff were associated with higher melt-season mean plume SSC values, but this relationship did not hold for individual rivers. High spatial variability between proximal plumes highlights the complex processes operating in Greenland's glacio–fluvial–fjord systems.

scholarly journals A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland

Geosciences ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 266 ◽  
Author(s):  
Kristoffer Szilas
Keyword(s):  
Magma Mixing ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Present Contribution ◽  
Data Set ◽  
Basaltic Rocks ◽  
The North ◽  
Metavolcanic Rocks ◽  
Geochemical Analyses ◽  
Southwest Greenland

The present contribution reviews bulk-rock geochemical data for mid-Archaean (ca. 3075–2840 Ma) metavolcanic rocks from the North Atlantic Craton of southwest Greenland. The data set includes the most recent high quality major and trace element geochemical analyses for ten different supracrustal/greenstone belts in the region. When distilling the data set to only include the least altered metavolcanic rocks, by filtering out obviously altered samples, mafic/ultramafic cumulate rocks, late-stage intrusive sheets (dolerites) and migmatites, the remaining data (N = 427) reveal two fundamentally distinct geochemical suites. The contrasting trends that emerge from the filtered geochemical data set, which best represents the melt compositions for these mid-Archaean metavolcanic rocks are: (1) tholeiitic (mainly basaltic) versus (2) calc-alkaline (mainly andesitic). These two rock suites are effectively separated by their La/Sm ratios (below or above three, respectively). It is demonstrated by geochemical modelling that the two contrasting suites cannot be related by either fractional crystallization or crustal assimilation processes, despite occurring within the same metavolcanic sequences. The tholeiitic basaltic rocks were directly mantle-derived, whereas the petrogenesis of the calc-alkaline andesitic rocks involve a significant (>50%) felsic component. The felsic contribution in the calc-alkaline suite could either represent slab-melt metasomatism of their mantle source, mafic-felsic magma mixing, or very large degrees of partial melting of mafic lower crust. At face value, the occurrence of andesites, and the negative Nb-Ta-Ti-anomalies of both suites, is consistent with a subduction zone setting for the origin of these metavolcanic rocks. However, the latter geochemical feature is inherent to processes involving crustal partial melts, and therefore independent lines of evidence are needed to substantiate the hypothesis that plate tectonic processes were already operating by the mid-Archaean.

scholarly journals IWV retrieval from ground GNSS receivers during NAWDEX

2021 ◽  
Vol 55 ◽  
pp. 13-22
Author(s):  
Pierre Bosser ◽  
Olivier Bock
Keyword(s):  
Water Vapor ◽  
North Atlantic ◽  
Regional Scale ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Spatial And Temporal Variability ◽  
Data Set ◽  
The North ◽  
The North Atlantic ◽  
Global Navigation Satellite

Abstract. A ground-based network of more than 1200 Global Navigation Satellite System (GNSS) Continuously Operating Reference Stations (CORS) was analysed using GIPSY-OASIS II software package for the documentation of time and space variations of water vapor in atmosphere during the North Atlantic Waveguide and Downstream impact EXperiment (NAWDEX) during fall 2016. The network extends throughout the North Atlantic, from the Caribbeans to Morocco through Greenland. This paper presents the methodology used for GNSS data processing, screening, and conversion of Zenith Tropospheric Delay (ZTD) estimates to Integrated Water Vapor content (IWV) using surface parameters from reanalysis. The retrieved IWV are used to evaluate the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses ERAI and ERA5. ERA5 shows an overall improvement over ERAI in representing the spatial and temporal variability of IWV over the study area. The mean bias is decreased from 0.31±0.63 to 0.19±0.56 kg m−2 (mean ±1σ over all stations) and the standard deviation reduced from 2.17±0.67 to 1.64±0.53 kg m−2 combined with a slight improvement in correlation coefficient from 0.95 to 0.97. At regional scale, both reanalyses show a general wet bias at mid and northern latitudes but a dry bias in the Caribbeans. We hypothesize this results from the different nature of data being assimilated over the tropical oceans. This GNSS IWV data set is intended to be used for a better description of the high impact weather events that occurred during the NAWDEX experiment.

scholarly journals Quaternary basaltic volcanic fields of the American Southwest

Geosphere ◽  
2021 ◽  
Author(s):  
Greg A. Valentine ◽  
Michael H. Ort ◽  
Joaquín A. Cortés
Keyword(s):  
Regional Scale ◽  
Plate Boundary ◽  
Poisson Model ◽  
Volcanic Field ◽  
American Southwest ◽  
Order Estimate ◽  
Recurrence Rates ◽  
Data Set ◽  
The North ◽  
Volcanic Fields

The southwestern United States contains numerous monogenetic basaltic volcanoes distributed in intraplate volcanic fields. We review, on a regional scale, our current understanding of the Quaternary basalts with a focus on aspects pertinent to hazard assessment, such as physical volcanology and geochronology, while also summarizing the several petrogenetic concep­tual models that have been proposed for the range of local tectonic settings in the region. We count 2229 volcanoes in 37 volcanic fields (including the Pinacate volcanic field, which is mostly in northern Sonora, Mexico). Volcanic landforms are dominantly scoria cones and ramparts with attendant lava fields that have a spectrum of ‘a’ā and blocky to pāhoehoe morphologies, while a small percentage of the volcanoes are maars and tuff cones. Explosive eruption styles that were driven mainly by magmatic volatiles, where they have been studied in detail, included Hawaiian, Strombolian, violent Strombolian, and sub-Plinian activity. The latter two have resulted in sub­stantial fallout deposits that can be traced tens of kilometers from source vents. Phreatomagmatic styles have produced pyroclastic current (mainly pyroclastic surges), ballistic, and fallout deposits. These eruption styles pose hazards to humans when they occur in populated areas and to air travel and regional infrastructure even in sparsely populated areas. All but one of the major volcanic fields (fields that contain ~100 or more Quaternary volcanoes) together form a northwest-southeast–trending band, which we suggest may reflect an influence of plate-boundary-related shearing on melt segregation in the upper mantle along with other factors; this view is consistent with recent global positioning system (GPS) and structural geologic data indicating the influence of dextral motion along the North America-Pacific plate boundary deep inside the Southwest. Of the 2229 Quaternary volcanoes identified, ~548 (25%) have been dated, and only ~15% have been dated with methods such as 40Ar/39Ar and cosmogenic surface exposure methods that are considered optimal for young basalts. Acknowledging the large uncertainty due to the poor geochronological data coverage, we use a simple Poisson model to pro­vide a first-order estimate of recurrence rates of monogenetic volcanoes on the scale of the region as a whole; recurrence rates using our compiled age data set range from 3.74 × 10−4 yr−1 to 8.63 × 10−4 yr−1. These values are only based on dated and mapped volcanoes, respectively, and do not account for undated and buried volcanoes or other uncertainties in the volcano count. The time between monogenetic eruptions in the Southwest is similar to the repose times of some polygenetic volcanoes, which suggests that the regional hazard is potentially commensurate with the hazard from a reawakening stratovolcano such as those in the Cascade Range. Notable in our review is that only a few volcanoes have been the subject of physical volcanological characterization, interpretation, and detailed petrologic study that may elu­cidate factors such as magma generation, ascent (including time scales), and controls on eruption style.

Regional-scale mapping for determining geochemical background values in soils of the Itacaiúnas River Basin, Brazil: The use of compositional data analysis (CoDA)

Geoderma ◽  
2020 ◽  
Vol 376 ◽  
pp. 114504 ◽  
Author(s):  
Prafulla Kumar Sahoo ◽  
Roberto Dall'Agnol ◽  
Gabriel Negreiros Salomão ◽  
Jair da Silva Ferreira Junior ◽  
Marcio Sousa Silva ◽  
...  
Keyword(s):  
Data Analysis ◽  
River Basin ◽  
Compositional Data ◽  
Regional Scale ◽  
Compositional Data Analysis ◽  
Geochemical Background ◽  
Background Values

scholarly journals The Orbiting Carbon Observatory-2: First 18 months of Science Data Products

2016 ◽  
Author(s):  
Annmarie Eldering ◽  
Chris W. O'Dell ◽  
Paul O. Wennberg ◽  
David Crisp ◽  
Michael R. Gunson ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Eastern China ◽  
Regional Scale ◽  
Central Africa ◽  
Retrieval Algorithm ◽  
Science Data ◽  
Data Set ◽  
The North ◽  
Atmospheric Carbon

Abstract. The Orbiting Carbon Observatory-2 (OCO-2) is the first National Aeronautics and Space Administration (NASA) satellite designed to measure atmospheric carbon dioxide (CO2) with the accuracy, resolution, and coverage needed to quantify CO2 fluxes (sources and sinks) on regional scales. OCO-2 was successfully launched on 2 July 2014, and joined the 705 km Afternoon Constellation on 3 August 2014. On monthly time scales, 7 to 12 % of these measurements are sufficiently cloud and aerosol free to yield estimates of the column-averaged atmospheric CO2 dry air mole fraction, XCO2, that pass all quality tests. During the first year of operations, the observing strategy, instrument calibration, and retrieval algorithm were optimized to improve both the data yield and the accuracy of the products. With these changes, global maps of XCO2 derived from the OCO-2 data are revealing some of the most robust features of the atmospheric carbon cycle. This includes XCO2 enhancements co-located with intense fossil fuel emissions in eastern US and eastern China, which are most obvious between October and December, when the north-south XCO2 gradient is small. Enhanced XCO2 coincident with biomass burning in the Amazon, central Africa, and Indonesia is also evident in this season. In May and June, when the north-south XCO2 gradient is largest, these sources are less apparent in global maps. During this part of the year, OCO-2 maps show a more than 10 ppm reduction in XCO2 across the northern hemisphere, as photosynthesis by the land biosphere rapidly absorbs CO2. As the carbon cycle science community continues to analyze these OCO-2 data, information on regional-scale sources (emitters) and sinks (absorbers) which impart XCO2 changes on the order of 1 ppm, as well as far more subtle features, will emerge from this high resolution, global data set.

The Chingandzha flora of the Okhotsk-Chukotka volcanic belt

Palaeobotany ◽  
2019 ◽  
Vol 10 ◽  
pp. 13-179
Author(s):  
L. B. Golovneva
Keyword(s):  
River Basin ◽  
Volcanic Belt ◽  
Flowering Plants ◽  
Sedimentary Deposits ◽  
North East ◽  
The North ◽  
Magadan Region ◽  
Chukotka Volcanic Belt ◽  
Systematic Composition ◽  
Coastal Lowlands

The Chingandzha flora comes from the volcanic-sedimentary deposits of the Chingandzha Formation (the Okhotsk-Chukotka volcanic belt, North-East of Russia). The main localities of the Chingandzha flora are situated in the Omsukchan district of the Magadan Region: on the Tap River (basin of the middle course of the Viliga River), on the Kananyga River, near the mouth of the Rond Creek, and in the middle reaches of the Chingandzha River (basin of the Tumany River). The Chingandzha flora includes 23 genera and 33 species. Two new species (Taxodium viligense Golovn. and Cupressinocladus shelikhovii Golovn.) are described, and two new combinations (Arctopteris ochotica (Samyl.) Golovn. and Dalembia kryshtofovichii (Samyl.) Golovn.) are created. The Chingandzha flora consists of liverworts, horsetails, ferns, seed ferns, ginkgoaleans, conifers, and angiosperms. The main genera are Arctop teris, Osmunda, Coniopteris, Cladophlebis, Ginkgo, Sagenoptepis, Sequoia, Taxodium, Metasequoia, Cupressinocladus, Protophyllocladus, Pseudoprotophyllum, Trochodendroides, Dalembia, Menispermites, Araliaephyllum, Quereuxia. The Chingandzha flora is distinct from other floras of the Okhotsk-Chukotka volcanic belt (OCVB) in predominance of flowering plants and in absence of the Early Cretaceous relicts such as Podozamites, Phoenicopsis and cycadophytes. According to its systematic composition and palaeoecological features, the Chingandzha flora is similar to the Coniacian Kaivayam and Tylpegyrgynay floras of the North-East of Russia, which were distributed at coastal lowlands east of the mountain ridges of the OCVB. Therefore, the age of the Chingandzha flora is determined as the Coniacian. This flora is assigned to the Kaivayam phase of the flora evolution and to the Anadyr Province of the Siberian-Canadian floristic realm. The Chingandzha flora is correlated with the Coniacian Aleeky flora from the Viliga-Tumany interfluve area and with other Coniacian floras of the OCVB: the Chaun flora of the Central Chukotka, the Kholchan flora of the Magadan Region and the Ul’ya flora of the Ul’ya Depression.

Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock
Keyword(s):  
River Basin ◽  
Detrital Zircon ◽  
Middle Part ◽  
Detrital Zircons ◽  
Powder River Basin ◽  
Zircon Age ◽  
Lower Eocene ◽  
The North ◽  
Mountain Front ◽  
Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

YUKAGIR GEOGRAPHICAL TERMS IN TOPONYMY OF THE KOLYMA RIVER BASIN

2020 ◽  
Vol 9 (4(73)) ◽  
pp. 29-33
Author(s):  
N.S. Bagdaryyn
Keyword(s):  
River Basin ◽  
Semantic Analysis ◽  
Comparative Method ◽  
Linguistic Analysis ◽  
Word Formation ◽  
Morphological Features ◽  
North East ◽  
The North ◽  
First Time ◽  
Kolyma River

The article continues the author's research on the toponymy of the North-East of the Sakha Republic, in particular the Kolyma river basin, in the aspect of the interaction of related and unrelated languages. The relevance of this work is defined in the description of local geographical terminology of Yukagir origin, as a valuable and important material in the further study of toponymy of the region. For the first time, the toponymy of the Kolyma river basin becomes the object of sampling and linguistic analysis of toponyms with local geographical terms of Yukagir origin in order to identify and analyze them linguistically. The research was carried out by comparative method, word formation, structural, lexical and semantic analysis. As a result of the research, phonetic and morphological features are revealed, the formation of local geographical terms and geographical names of Yukagir origin is outlined, and previously unrecorded semantic shifts and dialectisms are revealed. The most active in the formation of terms and toponyms is the geographical term iилil / eҕal 'coast‘, which is justified by the representation of the Yukagirs’ coast' home, housing

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