Ammonium abundance and short-wave infrared absorption spectra of altered rocks

2020 ◽  
Vol 20 (4) ◽  
pp. 451-460
Author(s):  
Keiko Hattori ◽  
Anna Fonseca ◽  
Tabetha Sheppard
Keyword(s):  
Absorption Spectra ◽  
Nitrogen Isotope ◽  
Short Wave ◽  
Absorption Feature ◽  
Rock Composition ◽  
Content Type ◽  
Fine Grained ◽  
Supplementary Material ◽  
Short Wave Infrared ◽  
Absorption Features

Rhyolitic rocks hosting the El Zapote epithermal Ag deposit are pervasively altered and contain ammonium ranging from 290 to 1750 ppm. High ammonium values are found in samples containing abundant fine-grained illite. This fine-grained illite shows overall low ratios of K/(Al + Fe), likely due to ammonium substituting K+. Samples containing high ammonium, greater than 1000 ppm in the proximity of Ag-bearing veins, show distinct absorption features of ammonium in short-wave infrared (SWIR) absorption spectra. Samples containing ammonium ranging from 500 to 1000 ppm show mixed absorption signatures; some show prominent absorption features related to ammonium, whereas others have no recognizable features. There is no discernible absorption feature related to ammonium for samples containing less than 500 ppm NH4. The data suggest that SWIR spectroscopy is useful in locating the proximal areas to mineralization, but the extent of ammonium alteration is much larger than that identified by SWIR spectroscopy. Nitrogen isotope compositions of ammonium are similar to those of sedimentary rocks, suggesting that the source of ammonium in altered rhyolite is sedimentary basement rocks in the area.Supplementary material: bulk rock composition is available at https://doi.org/10.6084/m9.figshare.c.5015663

Spatial variation in provenance signal: identifying complex sand sourcing within a Carboniferous basin using multiproxy provenance analysis.

2021 ◽  
pp. jgs2021-045
Author(s):  
B. Anders ◽  
S. Tyrrell ◽  
D. Chew ◽  
C. Mark ◽  
G. O'Sullivan ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Drainage System ◽  
Provenance Analysis ◽  
Rock Composition ◽  
Content Type ◽  
Metasedimentary Rocks ◽  
Sedimentary System ◽  
Supplementary Material ◽  
Sandstone Formation ◽  
Proterozoic Basement

Multiple factors (e.g. source rock composition, climate, nature/scale of sedimentary system) influence the volume and composition of sediment delivered to basins. Fluctuations in these parameters produce cryptic source signals which can vary within the same sedimentary system. Bespoke multi-proxy provenance approaches, targeted at minerals of variable stability, allow for an assessment of natural biasing (recycling) and intra-basinal spatial variations.Provenance of fluvial/deltaic sandstones (Mullaghmore Sandstone Formation) in the NW Carboniferous Basin, Ireland, has been constrained using zircon and apatite U-Pb geochronology, trace elements in apatite and Pb-in-K-feldspar analysis. Zircon U-Pb grain populations are consistent with feldspar data, suggesting Proterozoic basement highs offshore Ireland and Scotland were the main contributor with minor supply from Archean-Palaeoproterozoic rocks of Greenland/NW Scotland and Caledonian-aged rocks. However, apatite data shows a much larger proportion of Caledonian-aged grains of metamorphic origin, suggesting significant sediment was recycled from Neopropterozoic metasedimentary rocks. The spatial variation in provenance indicates that, at onset of clastic input, sediment was being routed to the basin through a complex drainage system, comprising of several discrete hinterland catchments, rather than supply from a single, large interconnected sedimentary system. Such complexities can only be identified with the careful application of a bespoke multi-proxy provenance approach.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5536691

Brittle–ductile fabrics and P–T conditions of deformation in the East Pernambuco shear zone (Borborema Province, NE Brazil)

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2020-109
Author(s):  
Paulo Castellan ◽  
Gustavo Viegas ◽  
Frederico M. Faleiros
Keyword(s):  
Shear Zone ◽  
Microstructural Analysis ◽  
Mineral Chemistry ◽  
Prism Slip ◽  
Content Type ◽  
Fine Grained ◽  
Brittle Ductile Transition ◽  
Epma Analysis ◽  
Borborema Province ◽  
Supplementary Material

Fabrics of the East Pernambuco shear zone (EPSZ) were studied via microstructural analysis, mineral chemistry and isochemical phase diagram modelling to constrain the pressure and temperature conditions of deformation during shearing. Granitic mylonites show fractured feldspar porphyroclasts embedded in a fine-grained, recrystallized quartzo-feldspathic matrix. These mylonites grade laterally into banded ultramylonites characterized by stretched feldspar clasts alternated with recrystallized quartz bands. Fractures in these ultramylonites are filled by phyllosilicates. The mineral chemistry of the feldspars points to systematic changes between porphyroclasts, grains within fractures and fine-grained mixtures. Quartz crystallographic fabrics in the mylonites suggest activation of prism slip, while the ultramylonites show the activation of both rhomb and basal slip systems. Thermodynamic modelling suggests that the mylonites were formed at 4.75 ± 0.25 kbar and 526 ± 9°C, while the ultramylonites yield conditions of 5.9 ± 1 kbar and 437 ± 17°C. These observations suggest that the EPSZ records a heterogeneous path of strain accommodation, marked by decreasing temperature from its western sector to its eastern termination. The differences in metamorphic conditions are consistent with a transitional, brittle–ductile strain regime. Such characteristics indicate that the EPSZ is a Neoproterozoic shear belt nucleated and heterogeneously exhumed at the brittle–ductile transition, possibly in an intracontinental setting.Supplementary Material: EPMA analysis of feldspars in Caruaru and Gravatá domains and T-X(O2) pseudosections are available at https://doi.org/10.6084/m9.figshare.c.5125957

An assessment of the Upper Succession and the related secondary reservoirs in the Welton Field, onshore UK

2016 ◽  
Vol 8 (1) ◽  
pp. 595-609 ◽  
Author(s):  
James Steventon ◽  
Mike Bowman
Keyword(s):  
Large Scale ◽  
Water Injection ◽  
Soft Rock ◽  
Oil Field ◽  
Content Type ◽  
Fine Grained ◽  
Delta Plain ◽  
Supplementary Material ◽  
Petrophysical Logs ◽  
Crevasse Splay

AbstractThe Welton oil field has produced nearly 20 MMBO (million barrels of oil) since discovery in 1981. Now in post-plateau decline, there is increasing reliance on a series of secondary reservoirs. Production has been from a suite of stacked reservoirs deposited by large-scale prograding delta-plain systems of early Westphalian age. Whilst the bulk of production has been from the Basal Succession, a considerable upside is considered to exist in the less well-studied Upper Succession that comprises predominantly distributary channel and crevasse splay deposits which have produced in excess of 3 MMBO. These accumulations occur within the Deep Soft Rock, Deep Hard Rock and Tupton reservoirs.This paper focuses on a sedimentological analysis of cored intervals, integrated with petrophysical logs and detailed production data to enable further recommendations to identify areas of undrained pay, along with identifying additional reservoir management activities that could optimize future offtake from the field. These reservoirs consist predominantly of very fine-grained sandstone, with permeability values rarely attaining 100 mD and average porosity values of 10–12%.Recommendations include executing tracer communication tests and building a detailed field model, as well as a pilot water-injection scheme to increase production from some of Welton's secondary reservoirs.Supplementary material: A full set of detailed sedimentological logs for each of the cored wells in this study is available at https://doi.org/10.6084/m9.figshare.c.3593984

scholarly journals Artificial Intelligence for Pigment Classification Task in the Short-Wave Infrared Range

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6150
Author(s):  
Emeline Pouyet ◽  
Tsveta Miteva ◽  
Neda Rohani ◽  
Laurence de Viguerie
Keyword(s):  
Treatment Approach ◽  
Short Wave ◽  
Data Cube ◽  
Infrared Range ◽  
Intrinsic Complexity ◽  
Short Wave Infrared ◽  
Absorption Features ◽  
Reference Samples ◽  
Historical Samples

Hyperspectral reflectance imaging in the short-wave infrared range (SWIR, “extended NIR”, ca. 1000 to 2500 nm) has proven to provide enhanced characterization of paint materials. However, the interpretation of the results remains challenging due to the intrinsic complexity of the SWIR spectra, presenting both broad and narrow absorption features with possible overlaps. To cope with the high dimensionality and spectral complexity of such datasets acquired in the SWIR domain, one data treatment approach is tested, inspired by innovative development in the cultural heritage field: the use of a pigment spectral database (extracted from model and historical samples) combined with a deep neural network (DNN). This approach allows for multi-label pigment classification within each pixel of the data cube. Conventional Spectral Angle Mapping and DNN results obtained on both pigment reference samples and a Buddhist painting (thangka) are discussed.

Methods of removal wide-stripe noise in short-wave infrared hyperspectral remote sensing image

Sensor Review ◽  
2019 ◽  
Vol 39 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Shi-Qi Huang ◽  
Wen-Sheng Wu ◽  
Li-Ping Wang ◽  
Xiang-Yang Duan
Keyword(s):  
Remote Sensing ◽  
Short Wave ◽  
Hyperspectral Remote Sensing ◽  
Moment Matching ◽  
Remote Sensing Images ◽  
Content Type ◽  
Short Wave Infrared ◽  
Hyperspectral Remote Sensing Images ◽  
The Impact ◽  
Hyperspectral Remote Sensing Image

Purpose This paper aims to study the removal of wide-stripe noise in hyperspectral remote sensing images. There is a great deal of stripe noises in short-wave infrared hyperspectral remote sensing image, especially wide-stripe noise, which brings great challenge to the interpretation and application of hyperspectral images. Design/methodology/approach To remove the noise and to reduce the impact based on in-depth study of the mechanism of the stripe noise generation and its distribution characteristics, this paper proposed two statistical local processing and moment matching algorithms for the elimination of wide-stripe noise, namely, the gradient mean moment matching (GMMM) algorithm and the gradient interpolation moment matching (GIMM) algorithm. Findings The experiments were carried out with the practical short-wave infrared hyperspectral image data and good experiment results were obtained. Experiments show that both can reduce the impact of wide-stripe noise, and the filtering effect and the application range of the GIMM algorithm is better than that of the GMMM algorithm. Originality/value Using new methods to deal with the hyperspectral remote sensing images, it can effectively improve the quality of hyperspectral images and improve their utilization efficiency and value.

scholarly journals Integrative 3D Geological Modeling Derived from SWIR Hyperspectral Imaging Techniques and UAV-Based 3D Model for Carbonate Rocks

2021 ◽  
Vol 13 (15) ◽  
pp. 3037
Author(s):  
Huy Hoa Huynh ◽  
Jaehung Yu ◽  
Lei Wang ◽  
Nam Hoon Kim ◽  
Bum Han Lee ◽  
...  
Keyword(s):  
3D Model ◽  
Imaging Techniques ◽  
Iron Hydroxide ◽  
Spectral Characteristics ◽  
Short Wave ◽  
Rock Classification ◽  
3D Geological Modeling ◽  
Logistic Regression Models ◽  
Rock Formations ◽  
Absorption Features

This paper demonstrates an integrative 3D model of short-wave infrared (SWIR) hyperspectral mapping and unmanned aerial vehicle (UAV)-based digital elevation model (DEM) for a carbonate rock outcrop including limestone and dolostone in a field condition. The spectral characteristics in the target outcrop showed the limestone well coincided with the reference spectra, while the dolostone did not show clear absorption features compared to the reference spectra, indicating a mixture of clay minerals. The spectral indices based on SWIR hyperspectral images were derived for limestone and dolostone using aluminum hydroxide (AlOH), hydroxide (OH), iron hydroxide (FeOH), magnesium hydroxide (MgOH) and carbonate ion (CO32−) absorption features based on random forest and logistic regression models with an accuracy over 87%. Given that the indices were derived from field data with consideration of commonly occurring geological units, the indices have better applicability for real world cases. The integrative 3D geological model developed by co-registration between hyperspectral map and UAV-based DEM using best matching SIFT descriptor pairs showed the 3D rock formations between limestone and dolostone. Moreover, additional geological information of the outcrop was extracted including thickness, slope, rock classification, strike, and dip.

scholarly journals Evaporated Se x Te 1‐ x Thin Films with Tunable Bandgaps for Short‐Wave Infrared Photodetectors

2020 ◽  
Vol 32 (38) ◽  
pp. 2001329 ◽  
Author(s):  
Chaoliang Tan ◽  
Matin Amani ◽  
Chunsong Zhao ◽  
Mark Hettick ◽  
Xiaohui Song ◽  
...  
Keyword(s):  
Thin Films ◽  
Short Wave ◽  
Infrared Photodetectors ◽  
Short Wave Infrared
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