Geochemistry and chemostratigraphical correlation of slates, marbles and quartzites of the Appin Group, Argyll, Scotland

1983 ◽  
Vol 73 (4) ◽  
pp. 251-278 ◽  
Author(s):  
Arthur H. Hickman ◽  
Alan E. Wright
Keyword(s):  
Trace Elements ◽  
Function Analysis ◽  
Statistical Treatment ◽  
Climatic Changes ◽  
Insoluble Residue ◽  
Stratigraphic Correlation ◽  
Quartz Sands ◽  
Deltaic Deposit ◽  
Viable Method

ABSTRACTApproximately 700 samples from five slate, three marble and five quartzite units have been analysed for 26 elements to determine the use of geochemistry in stratigraphic correlation. Statistical treatment of the data has established that for all the slates and marbles, and certain of the quartzites, geochemistry is a viable method of distinguishing units of similar lithology. The most useful elements for distinguishing the four main slate units are P, Cr. Zn, Cu and, to a lesser extent, Rb, Sr, Y, Nb, Ba, La and Ce. Sr may indicate climatic changes or variable organic activity. The three marble units were considered as three limestone and three dolostone types. Dolostones are distinguished by high insoluble residue contents and the elements that distinguish between the dolostones are heavily influenced by these. Limestones, however, have very large differences in Sr. SiO2, Al2O3, K2O, Cr, Mn, Cu, Rb, Sr, Y and Zr have been used in discrimint function analysis. These parameters are strongly controlled by the insoluble residue with Al2O3, K2O, Cr and Rb being correlated with shaley impurities and SiO2, TiO2 and Zr with sandy impurities. Sr, Pb, Y and Zn, and to a lesser extent S and Mn, appear to be associated with the carbonate fraction.The quartzites were found to be of three major types: (1) a very variable deltaic deposit (Appin Quartzite Formation), (2) marine bodies of immature quartz sands (Glen Coe and Eilde Quartzite formations) and (3) highly mature quartz sands (Binnein Quartzite Formation and northerly outcrops of the Glen Coe Quartzite Formation). It is possible to distinguish these three types on the basis of some trace elements (Zn, Rb, Sr, Y, Ba, La, Ce) but it is not feasible to distinguish between the Glen Coe and Eilde quartzites purely on geochemistry. The Eilde Flags, an immature estuarine sandstone, has a geochemistry intermediate between that of the quartzites and the pelites, although with higher CaO, Zr and Ba than either.

scholarly journals Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia

2013 ◽  
Vol 10 (2) ◽  
pp. 2205-2244 ◽  
Author(s):  
I. Antcibor ◽  
S. Zubrzycki ◽  
A. Eschenbach ◽  
L. Kutzbach ◽  
D. Bol'shiyanov ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Trace Metal ◽  
Climatic Changes ◽  
River Delta ◽  
Metal Distribution ◽  
Background Concentrations ◽  
Lena River ◽  
Trace Metal Distribution ◽  
Lena River Delta

Abstract. Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N–69.5° N) representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co) and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island) showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA) revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were similar to background levels reported for other pristine arctic areas and did not exceed mean global background concentrations examined for the continental crust as well as for the world's soils.

Automations in Chemostratigraphy: Toward Robust Chemical Data Analysis and Interpretation

2021 ◽  
Author(s):  
Nikolaos A. Michael ◽  
Christian Scheibe ◽  
Neil W. Craigie
Keyword(s):  
Machine Learning ◽  
Function Analysis ◽  
Analytical Techniques ◽  
Machine Learning Techniques ◽  
Geochemical Data ◽  
Correlation Technique ◽  
Stratigraphic Correlation ◽  
Geological Processes ◽  
Early Results ◽  
Geological Formations

Abstract Elemental chemostratigraphy has become an established stratigraphic correlation technique over the last 15 years. Geochemical data are generated from rock samples (e.g., ditch cuttings, cores or hand specimens) for up to c. 50 elements in the range Na-U in the periodic table using various analytical techniques. The data are commonly displayed and interpreted as ratios, indices and proxy values in profile form against depth. The large number of possible combinations between the determined elements (more than a thousand combinations), makes it a time-consuming effort to identify meaningful variations that resulted in correlative chemostratigraphic boundaries and zones between wells. The large number of combination means that 30-40% of the information is not used for the correlations that maybe crucial to understand the geological processes. Automation and artificial intelligence (AI) are envisaged as likely solutions to this challenge. Statistical and machine learning techniques are tested as a first step to automate and establish a workflow to define (chemo-) stratigraphic boundaries, and to identify geological formations. The workflow commences with a quality check of the input data and then with principle component analysis (PCA) as a multivariate statistical method. PCA is used to minimize the number of elements/ratios plotted in profile form, whilst simultaneously identifying multidimensional relationships between them. A statistical boundary picking method is then applied define chemostratigraphic zones, for which reliability is determined utilizing quartile analysis, which tests the overlap of chemical signals across these statistical boundaries. Machine learning via discriminant function analysis (DFA) has been developed to predict the placement of correlative boundaries between adjacent sections/wells. The proposed workflow has been tested on various geological formations and areas in Saudi Arabia. The chemostratigraphic correlations proposed using this workflow broadly correspond to those defined in the standard workflow by experienced chemostratigraphers, while interpretation times and subjectivity are reduced. While machine learning via DFA is currently further researched, early results of the workflow are very encouraging. A user-friendly software application with workflows and algorithms ultimately leading to automation of the processes is under development.

Immobile trace elements and Archean volcanic stratigraphy in the Timmins mining area, Ontario

1979 ◽  
Vol 16 (2) ◽  
pp. 305-311 ◽  
Author(s):  
J. F. Davies ◽  
R. W. E. Grant ◽  
R. E. S. Whitehead
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
No Value ◽  
Volcanic Rocks ◽  
Mining Area ◽  
Stratigraphic Correlation ◽  
Trace Element Data ◽  
Volcanic Stratigraphy ◽  
Lithostratigraphic Units ◽  
Hydrolysis Of

Carbonate alteration and hydrolysis of mafic volcanic rocks in the Timmins area have been accompanied by mobilization and redistribution of alkalies, CaO, MgO, and FeO. These major oxides are of dubious value in classifying the volcanic rocks, and are of no value in identifying and correlating lithostratigraphic units. The trace elements Y, Zr, TiO2, and Cr, whose fractionation tendencies parallel those of the alkalies, FeO and MgO, are relatively immobile and display characteristic patterns within different volcanic units. The trace-element patterns are highly diagnostic, and their distribution corresponds to the distribution of lithostratigraphic units. Immobile trace-element data represent a potentially valuable tool in stratigraphic correlation of Archean volcanic rocks, whether altered or unaltered.

Discriminant Function Analysis of Glass Chemistry of New Zealand and North American Tephra Deposits

1994 ◽  
Vol 41 (1) ◽  
pp. 70-81 ◽  
Author(s):  
Philip A.R. Shane ◽  
Paul C. Froggatt
Keyword(s):  
Trace Elements ◽  
New Zealand ◽  
Discriminant Function ◽  
Discriminant Function Analysis ◽  
Function Analysis ◽  
Taupo Volcanic Zone ◽  
Relative Significance ◽  
Major Oxides ◽  
Long Valley ◽  
Selection Of

AbstractMajor, trace, and rare earth element analyses of volcanic glass are used separately or in combination for correlating Quaternary tephras, often by graphical or simple comparative methods. We have taken a statistical approach using discriminant function analysis (DFA) to assess the relative discriminating power of the different elements in volcanic glasses from several tectonovolcanic provinces. We found that major oxides are powerful discriminating variables for widespread tephras from the Taupo Volcanic Zone in New Zealand and here they can be more discriminating than trace elements. A wide selection of tephras from the western United States can also be distinguished on major oxides alone, particularly those from Cascade Range volcanoes. For tephras from large intracontinental calderas, such as Long Valley or Yellowstone, REE and trace elements are more effective at discriminating than major oxides. However, tephras erupted from the Long Valley area can be distinguished on major oxide composition by DFA, despite their similar chemistry. The selection and relative significance of different elements for discriminating tephras depends on the total data set being compared, as well as the source volcano and the individual eruptive events. Caution must be exercised in the nonstatistical selection of compositional data for characterizing tephras: DFA is a more powerful and objective tool for the comparison of tephra chemistry.

Climatic changes indicated by trace elements in the Chagelebulu Stratigraphic Section, Badain Jaran Desert, China, since 150 kyr B.P.

2008 ◽  
Vol 46 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Yi Yang ◽  
Bao-sheng Li ◽  
Shi-fan Qiu ◽  
Zheng Wu ◽  
Quan-zhou Gao ◽  
...  
Keyword(s):  
Trace Elements ◽  
Climatic Changes ◽  
Badain Jaran Desert ◽  
Stratigraphic Section

Microanalytical Identification of a New Zr-Nb-Fe Phase

1990 ◽  
Vol 48 (2) ◽  
pp. 132-133
Author(s):  
O.T. Woo ◽  
G.J.C. Carpenter
Keyword(s):  
Trace Elements ◽  
Cold Rolling ◽  
Proportionality Factor ◽  
Tube Material ◽  
X Ray ◽  
Metal Foils ◽  
Arc Melting ◽  
Intermetallic Particles ◽  
Intermetallic Precipitates ◽  
Cold Worked

To study the influence of trace elements on the corrosion and hydrogen ingress in Zr-2.5 Nb pressure tube material, buttons of this alloy containing up to 0.83 at% Fe were made by arc-melting. The buttons were then annealed at 973 K for three days, furnace cooled, followed by ≈80% cold-rolling. The microstructure of cold-worked Zr-2.5 at% Nb-0.83 at% Fe (Fig. 1) contained both β-Zr and intermetallic precipitates in the α-Zr grains. The particles were 0.1 to 0.7 μm in size, with shapes ranging from spherical to ellipsoidal and often contained faults. β-Zr appeared either roughly spherical or as irregular elongated patches, often extending to several micrometres.The composition of the intermetallic particles seen in Fig. 1 was determined using Van Cappellen’s extrapolation technique for energy dispersive X-ray analysis of thin metal foils. The method was employed to avoid corrections for absorption and fluorescence via the Cliff-Lorimer equation: CA/CB = kAB · IA/IB, where CA and CB are the concentrations by weight of the elements A and B, and IA and IB are the X-ray intensities; kAB is a proportionality factor.

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