scholarly journals Rock alteration at the post-Variscan nonconformity: implications for Carboniferous–Permian surface weathering versus burial diagenesis and paleoclimate evaluation

Solid Earth ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 1165-1184
Author(s):  
Fei Liang ◽  
Jun Niu ◽  
Adrian Linsel ◽  
Matthias Hinderer ◽  
Dirk Scheuvens ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Basaltic Andesite ◽  
Inductively Coupled Plasma ◽  
Volcanic Rocks ◽  
Polarization Microscopy ◽  
Burial Diagenesis ◽  
X Ray ◽  
Physical Weathering ◽  
Geochemical Indices

Abstract. A nonconformity refers to a hiatal surface located between metamorphic or igneous rocks and overlying sedimentary or volcanic rocks. These surfaces are key features with respect to understanding the relations among climate, lithosphere and tectonic movements during ancient times. In this study, the petrological, mineralogical and geochemical characteristics of Variscan basement rock as well as its overlying Permian volcano-sedimentary succession from a drill core in the Sprendlinger Horst, Germany, are analyzed by means of polarization microscopy, and environmental scanning electron microscope, X-Ray diffraction, X-ray fluorescence and inductively coupled plasma mass spectrometry analyses. In the gabbroic diorite of the basement, the intensity of micro- and macro-fractures increases towards the top, indicating an intense physical weathering. The overlying Permian volcanic rock is a basaltic andesite that shows less intense physical weathering compared with the gabbroic diorite. In both segments, secondary minerals are dominated by illite and a mixed-layer phase of illite and smectite (I–S). The corrected chemical index of alteration (CIA) and the plagioclase index of alteration (PIA) indicate an intermediate to unweathered degree in the gabbroic diorite and an extreme to unweathered degree in the basaltic andesite. The τ values for both basaltic andesite and gabbroic diorite indicate an abnormal enrichment of K, Rb and Cs that cannot be observed in the overlying Permian sedimentary rocks. Accompanying minerals such as adularia suggest subsequent overprint by (K-rich) fluids during burial diagenesis which promoted the conversion from smectite to illite. The overall order of element depletion in both basaltic andesite and gabbroic diorite during the weathering process is as follows: large-ion lithophile elements (LILEs) > rare earth elements (REEs) > high-field-strength elements (HFSEs). Concerning the REEs, heavy rare earth elements (HREEs) are less depleted than light rare earth elements (LREEs). Our study shows that features of supergene physical and chemical paleo-weathering are well conserved at the post-Variscan nonconformity despite hypogene alteration. Both can be distinguished by characteristic minerals and geochemical indices. Based on these results, a new workflow to eliminate distractions for paleoclimate evaluation and evolution is developed.

scholarly journals Rock alteration at the post-Variscan nonconformity: implications for Carboniferous-Permian surface weathering versus burial diagenesis and paleoclimate evaluation

2021 ◽  
Author(s):  
Fei Liang ◽  
Jun Niu ◽  
Adrian Linsel ◽  
Matthias Hinderer ◽  
Dirk Scheuvens ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Basaltic Andesite ◽  
Inductively Coupled Plasma ◽  
Volcanic Rocks ◽  
Polarization Microscopy ◽  
Burial Diagenesis ◽  
X Ray ◽  
Physical Weathering ◽  
Geochemical Indices

Abstract. A nonconformity refers to a hiatal surface located between metamorphic or igneous rocks and overlying sedimentary or volcanic rocks. Those surfaces are key features to understand the relations among climate, lithosphere and tectonic movements during ancient time. In this study, the petrological, mineralogical, and geochemical characteristics of Variscan basement rock and its overlying Permian volcano-sedimentary succession from a drill core in the Sprendlinger Horst, Germany are analyzed by means of polarization microscopy, and environmental scanning electron microscope, X-Ray diffraction, X-ray fluorescence and Inductively Coupled Plasma Mass Spectrometry analyses. In the gabbroic diorite of the basement, the intensity of micro- and macro-fractures increases towards the top indicating an intense physical weathering. The overlying Permian volcanic rock is a basaltic andesite which shows less intense physical weathering compared to the gabbroic diorite. In both segments, secondary minerals are dominated by illite and a mix-layer phase of illite and smectite (I/S). The corrected chemical index of alteration (CIA) and the plagioclase index of alteration (PIA) indicate an intermediate to unweathered degree in the gabbroic diorite and an extreme to unweathered degree in the basaltic andesite. The τ value for both basaltic andesite and gabbroic diorite indicate an abnormal enrichment of K, Rb, and Cs that cannot be observed in the overlying Permian sedimentary rocks. Accompanying hydrothermal minerals such as adularia suggest subsequent overprint by (K-rich) hydrothermal fluids during burial diagenesis which promoted the conversion from smectite to illite. The overall order of element depletion in both basaltic andesite and gabbroic diorite during the weathering process is as follows: Large Ion Lithophile Elements (LILE) > Rear earth elements (REE) > High Field Strength Element (HFSE). Concerning the REE, heavy rare earth elements (HREE) are less depleted than light rare earth elements (LREE). Our study shows that features of supergene physical and chemical paleo-weathering are well conserved at the post-Variscan nonconformity despite hypogene alteration. Both can be distinguished by characteristic minerals and geochemical indices, with the results, a new workflow to eliminate distractions for paleoclimate evaluation and evolution is well developed.

Quantitative Cathodoluminescence Mapping with Application to a Kalgoorlie Scheelite

2009 ◽  
Vol 15 (3) ◽  
pp. 222-230 ◽  
Author(s):  
Colin M. MacRae ◽  
Nicholas C. Wilson ◽  
Joel Brugger
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Trace Element Level ◽  
Gaussian Peak ◽  
X Ray ◽  
Element Abundances ◽  
Inductively Coupled ◽  
Peak Fitting

AbstractA method for the analysis of cathodoluminescence spectra is described that enables quantitative trace-element-level distributions to be mapped within minerals and materials. Cathodoluminescence intensities for a number of rare earth elements are determined by Gaussian peak fitting, and these intensities show positive correlation with independently measured concentrations down to parts per million levels. The ability to quantify cathodoluminescence spectra provides a powerful tool to determine both trace element abundances and charge state, while major elemental levels can be determined using more traditional X-ray spectrometry. To illustrate the approach, a scheelite from Kalgoorlie, Western Australia, is hyperspectrally mapped and the cathodoluminescence is calibrated against microanalyses collected using a laser ablation inductively coupled plasma mass spectrometer. Trace element maps show micron scale zoning for the rare earth elements Sm3+, Dy3+, Er3+, and Eu3+/Eu2+. The distribution of Eu2+/Eu3+ suggests that both valences of Eu have been preserved in the scheelite since its crystallization 1.63 billion years ago.

scholarly journals Garnets from Val d’Ala Rodingites, Piedmont, Italy: An Investigation of Their Gemological, Spectroscopic and Crystal Chemical Properties

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 728 ◽  
Author(s):  
Valeria Diella ◽  
Rosangela Bocchio ◽  
Nicoletta Marinoni ◽  
Franca Caucia ◽  
Maria Iole Spalla ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Inductively Coupled Plasma ◽  
Chemical Properties ◽  
Western Alps ◽  
Drift Spectroscopy ◽  
X Ray ◽  
Heavy Rare Earth Elements ◽  
Diffuse Reflectance Infrared

In Val d’Ala (Piedmont, Western Alps, Italy), the more interesting rocks for the mineralogical research are represented by rodingites (rich in mineralized veins and fractures) associated with serpentinites in the eclogitized oceanic crust of Piemonte Zone, south of Gran Paradiso Massif. Among the vein-filling minerals, garnets are the most appreciated as mineral specimens and, in less degree despite their vivid and rich colors, for their potential as gem-quality materials. This study provides a complete gemological characterization of five faceted samples and offers new information by means of Synchrotron X-ray computed micro-tomography imaging gem features. Electron-probe microanalysis (EMPA) and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) established that the chemical composition of garnets from different localities, resulted both close to pure andradite, enriched in light rare earth elements (LREE) with a positive Eu anomaly, and grossular-andradite solid solution (grandite), enriched in heavy rare earth elements (HREE). X-ray powder diffraction analyses indicate the possible coexistence of almost pure grossular and andradite. A spectroscopic approach, commonly used with gem-like material, by Raman and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, completes the characterization of the samples. The new data on the textural and geochemical features of the grandite and andradite garnets suggest local growth processes under various chemical and oxidation conditions of metasomatic and metamorphic fluids interacting with the host-rocks. Garnets represent long-lasting mineral records of the complex geological history of the Val d’Ala rodingitic dikes during their oceanic- and subduction-related metamorphic evolution.

ANALYSIS OF TRACE RARE EARTH ELEMENTS IN MISCH METAL BY MEANS OF ITP-PIXE METHOD

1993 ◽  
Vol 03 (01) ◽  
pp. 89-102 ◽  
Author(s):  
JIAN-YING HU ◽  
TAKESHI HIROKAWA ◽  
FUMITAKA NISHIYAMA ◽  
GOJI KIMURA ◽  
YOSHIYUKI KISO ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Inductively Coupled Plasma ◽  
Minor Element ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray ◽  
Minor Elements ◽  
Misch Metal ◽  
Pixe Method

A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE(isotachophoresis—Particle Induced X-ray Emission) : The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotacho-phoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca. 10% accuracy was achieved for each minor element except for Sm(23%), Gd(17%) and Yb(18%). The analytical results by ITP-PIXE were compared with those by means of ICP-AES(Inductively Coupled Plasma—Atomic Emission Spectrometry).

scholarly journals Causes of variations of trace and rare earth elements concentration in lakes bottom sediments in the Bory Tucholskie National Park, Poland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariusz Sojka ◽  
Adam Choiński ◽  
Mariusz Ptak ◽  
Marcin Siepak
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Spatial Variability ◽  
Bottom Sediments ◽  
National Park ◽  
Anthropogenic Sources ◽  
Geochemical Processes ◽  
Natural Processes ◽  
Sources Of Pollution ◽  
Geochemical Indices

AbstractThe objective of this study was to analyse spatial variability of the trace elements (TEs) and rare earth elements (REEs) concentration in lake bottom sediments in Bory Tucholskie National Park (BTNP); Poland. The following research questions were posed: which factors have a fundamental impact on the concentration and spatial variability of elements in bottom sediments, which of the elements can be considered as indicators of natural processes and which are related to anthropogenic sources. The research material was sediments samples collected from 19 lakes. The concentrations of 24 TEs and 14 REEs were determined. The analyses were carried out using the inductively coupled plasma mass spectrometry (ICP-QQQ). Cluster analysis and principal component analysis were used to determine the spatial variability of the TEs and REEs concentrations, indicate the elements that are the indicators of natural processes and identify potential anthropogenic sources of pollution. The geochemical background value (GBV) calculations were made using 13 different statistical methods. However, the contamination of bottom sediments was evaluated by means of the index of geo-accumulation, the enrichment factor, the pollution load index, and the metal pollution index. The BTNP area is unique because of its isolation from the inflow of pollutants from anthropogenic sources and a very stable land use structure over the last 200 years. This study shows high variability of TE and REE concentrations in lake sediments. The values of geochemical indices suggest low pollution of lakes bottom sediments. It was found that TEs originated mainly from geogenic sources. However, the concentrations of Li, Ni, Sc, Se, Be, Se, Ag, Re, Tl, Cd, Sb and U may be related to the impact of point sources found mainly in the Ostrowite Lake. Almost all REEs concentrations were strongly correlated and their presence was linked to with geochemical processes. The elements allowing to identify natural processes and anthropogenic pollution sources were Cr, Co, Cu, Ag, Cd, Zn, Bi, Re, Ba, Al and Rb in TEs group and Nd, Gd, Yb, Lu, Eu, Dy and Ce in REEs group. The analysis shows high spatial variability of TE and REE concentrations in lake sediments. The values of geochemical indices point to low pollution of lakes sediments. The anthropogenic sources only for two lakes had an impact on concentrations of selected TEs and REEs. The analyses allowed to identify elements among TEs and REEs documenting geochemical processes and those indicating anthropogenic sources of pollution.

Sign in / Sign up

Export Citation Format

Share Document