The lower Proterozoic Fern Creek Formation, northern Michigan: mineral and bulk geochemical evidence for its glaciogenic origin

2002 ◽  
Vol 39 (4) ◽  
pp. 481-492 ◽  
Author(s):  
Anne Argast
Keyword(s):  
Rare Earth ◽  
Chemical Weathering ◽  
Chemical Index ◽  
Quartz Arenite ◽  
Bulk Chemical ◽  
Chemical Index Of Alteration ◽  
Rare Earth Mineral ◽  
Chemical Trends ◽  
Northern Michigan ◽  
Bulk Chemistry

Bulk chemical data indicate the Fern Creek Formation (Early Proterozoic, Marquette Range Supergroup, Lower Chocolay Group) originated as a glacial till, resolving an old argument about the correct interpretation for diamictite-containing units within the formation. There are poor correlations among SiO2, Al2O3, and K2O, and the chemical index of alteration averages 55. These are qualities characteristic of tills and other sediments accumulated in the absence of chemical weathering and transport-induced sorting and inconsistent with an origin as a fluvial deposit (the principal alternate hypothesis). The Archean Carney Lake Gneiss might be the source for at least the lower portions of the Fern Creek Formation. Compositions are similar, and rare earth element trends in the Fern Creek Formation are consistent with derivation from an Archean high-grade terrane. Pegmatites in the gneiss could be the source for monazite, huttonite, and an unnamed fluor-hydroxy-rare earth mineral that occurs in the midsection of the Fern Creek Formation. In addition, mineral and bulk chemical trends are consistent with models involving deep erosion of a complex Archean source, similar to models previously developed for Gowganda tills in the Huronian Supergroup. Samples of the Sturgeon River Quartzite occurring above the Fern Creek Formation were also analyzed. The bulk chemistry is consistent with a well-sorted, supermature quartz arenite.

Reconstructing chemical weathering during the Lower Mesozoic in the Western-Central Mediterranean area: a review of geochemical proxies

2017 ◽  
Vol 155 (4) ◽  
pp. 944-954 ◽  
Author(s):  
FRANCESCO PERRI
Keyword(s):  
Rift Valley ◽  
Chemical Weathering ◽  
Mineralogical Composition ◽  
Mediterranean Area ◽  
Climatic Changes ◽  
Central Mediterranean ◽  
Geochemical Proxies ◽  
Chemical Index ◽  
Chemical Index Of Alteration ◽  
Mineralogical Compositions

AbstractThe Triassic–Jurassic rift-valley stage of Tethyan rifting in the Western-Central Mediterranean area is characterized by a development of a puzzle of plates and microplates with the deposition of continental redbeds (in the internal domains of the Gibraltar Arc and Calabria–Peloritani Arc) that can be considered a regional lithosome. This paper aims to reconstruct the chemical weathering conditions of the Triassic–Jurassic boundary in the Western-Central Mediterranean area using the geochemical and mineralogical composition of continental redbed mudrocks of Mesozoic age. The mudrocks from the Calabria–Peloritani Arc show higher values of weathering (mobility) indices (αMg=(Al/Mg)sed/(Al/Mg)UCC;αK=(Th/K)sed/(Th/K)UCC;αBa=(Th/Ba)sed/(Th/Ba)UCC) than the Gibraltar Arc samples. Furthermore, the CIA (Chemical Index of Alteration) and MIA (Mineralogical Index of Alteration) values and the ‘Rb-type indices’ (e.g. Rb/Sr and Rb/K ratios) are higher for the Calabria–Peloritani Arc mudrocks than the Gibraltar Arc samples. All these geochemical proxies closely resemble each other and show similar variations suggesting climatic changes towards humid conditions through the Uppermost Triassic to Lowermost Jurassic that favoured chemical weathering conditions. This period is probably characterized by seasonal climate alternations corresponding to an increase in palaeoclimatic humidity. The mineralogical compositions of the Mesozoic mudrocks further confirm these indications as shown by a higher abundance of kaolinite, related to warm–humid conditions, in the Calabria–Peloritani Arc mudrocks than in those of the Gibraltar Arc.

scholarly journals Assessing sediment pollution by applying some geochemical indices for Al-Wind River banks/ East of Iraq

2019 ◽  
pp. 1711-1719
Author(s):  
Iman A. Al-Ali
Keyword(s):  
Enrichment Factor ◽  
Chemical Weathering ◽  
Contamination Factor ◽  
Anthropogenic Pollution ◽  
Sediment Pollution ◽  
Pollution Indices ◽  
Polluted Sediments ◽  
Chemical Index ◽  
Chemical Index Of Alteration ◽  
Cu And Zn

15 sediment samples were collected; 8 samples from the eastern bank, and 7 samples from the western bank of Al-Wind River in Diyala governorate to assess the sediment pollution in some trace elements such as Fe, Ni, Cd, Zr, Zn and Cu in addition to some oxides such as Al2O3, CaO, Na2O and K2O to find the effect of anthropogenic pollution and the industrial production on the sediment closed especially Naftkhana by using some geochemical pollution indices such as: geoaccumulation factor (I-geo), enrichment factor (EF),contamination factor (CF), pollution loud index (PLI) and to evaluate the degree of weathering by Applying the Chemical Index of Alteration (CIA)in both banks of Al-Wind River. The results of general contamination factors indicate that the eastern bank of Al-Wind River especially that closed by Naftkhana area having quite more concentrations of trace element and oxides from the western bank. The results of I-geo presents unpolluted sediment with Pb and Fe and slightly polluted with Zn, Cu, and Ni in both banks, while the western bank in some locations recorded of moderately polluted sediments with Ni and slightly to moderately polluted sediments with Cu and Zn and reach moderately severely polluted in the eastern bank. The contamination factor (CF) for Ni and Zr classified as class 2 which indicate moderately contamination to severely pollute in both banks, while Fe, Pb, Cu and Zn conbankred unpolluted in both banks. Enrichment factor (EF) for Fe, Pb, Zr and Cu are conbankred deficiency to low enrichment the range of natural variability, while Ni record  high values reached to 6.4 indication of anthropogenic inputs. Pollution load Index (PLI) is perfection and classified as class 0 in both banks. Chemical index of alteration (CIA) reflecting the chemical weathering intensity especially for the western bank.

scholarly journals Geochemistry of the Permian sandstones from the Malužiná Formation in the Malé Karpaty Mts (Hronic Unit, Western Carpathians, Slovakia): implications for source-area weathering, provenance and tectonic setting

2013 ◽  
Vol 64 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Marek Vďačný ◽  
Anna Vozárová ◽  
Jozef Vozár
Keyword(s):  
Continental Margin ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Source Area ◽  
Chemical Index ◽  
Fold Belts ◽  
Rifted Continental Margin ◽  
Bulk Chemical ◽  
Chemical Index Of Alteration ◽  
Ree Patterns

Abstract The Permian sandstones of the Malužiná Formation in the northern part of the Malé Karpaty Mts are dominantly quartzofeldspathic and quartzolithic in composition with abundant feldspars and volcanic, plutonic igneous and less metasedimentary lithic fragments, indicating the sand grains were derived from a basement uplift and recycled orogen. The Malužiná Formation sandstones have moderate to high SiO2 contents (68-85 wt. %; on average 76 wt. %), TiO2 concentrations averaging 0.3 wt. %, Al2O3 contents of about 12 wt. %, and Fe2O3 (total Fe as Fe2O3) + MgO contents of around 2.9 wt. %. The Chemical Index of Alteration (CIA) values for the Permian Malužiná Formation sandstones vary from 45 to 68 with an average of 55, indicating low to moderate weathering of the source area. The bulk chemical composition and selected trace elements preserve the signatures of a felsic and intermediate igneous provenance, and suggest mostly an active continental margin tectonic setting of the source area for the Malužiná Formation sandstones. The Eu/Eu* (~0.78), La/Sc (~7.28), Th/Sc (~2.10), La/Co (~6.67), Th/Co (~1.85), and Cr/Th (~6.57) ratios as well as the chondrite-normalized REE patterns with flat HREE, LREE enrichment, and negative Eu anomalies indicate derivation of the Malužiná Formation sandstones from felsic rock sources. The deposition of the Malužiná Formation sandstones took place in a rifted continental margin environment supplied from collision orogen on a thick continental crust composed of rocks of older fold belts.

Provenance of lower Cambrian quartz arenite on southwestern Baltica: Weathering versus recycling

2020 ◽  
Vol 90 (5) ◽  
pp. 493-512
Author(s):  
Sanne Lorentzen ◽  
Tonje Braut ◽  
Carita Augustsson ◽  
Johan P. Nystuen ◽  
Jens Jahren ◽  
...  
Keyword(s):  
Lower Cambrian ◽  
Mineral Assemblage ◽  
Chemical Weathering ◽  
Source Area ◽  
Heavy Mineral ◽  
Provenance Analysis ◽  
Source To Sink ◽  
Quartz Arenite ◽  
Chemical Index Of Alteration ◽  
Southern Norway

ABSTRACT Lower Cambrian quartz arenite deposits have a world-wide occurrence and are also present on Baltica. However, the processes influencing the deposits from source to sink have not been accordingly investigated. The provenance of these deposits is crucial for the understanding of the extent of chemical weathering in the cratonic drainage area and reworking at the broad shallow shelves of Baltica during early Cambrian time. Provenance analysis and study of weathering effects was done for lower Cambrian sandstone from southern Scandinavia, including southern Norway, southern Sweden, and Bornholm (Denmark). For the quartz-arenite sandstone of the Ringsaker Member and the Hardeberga Formation, predominantly moderately weathered felsic–intermediate plutonic and meta-igneous source terranes are suggested from negative Eu anomalies, high LaN/YbN, and low to moderate Ti/Nb ratios, as well as trace amounts of plutonic lithoclasts. Similarly, a felsic–intermediate igneous and metamorphic signature is indicated in the heavy-mineral assemblage and a dominance of dark cathodoluminescence of quartz in a special study of samples from Bornholm, thus suggesting a mixed provenance of local granitoid–orthogneissic Mesoproterozoic basement and distant sources from the Transscandinavian Igneous Belt for the Hardeberga Formation on Bornholm. High percentages of mostly rounded ultra-stable heavy-mineral grains, quartz, and extremely high SiO2/Al2O3 ratios indicate a compositionally and texturally mature sand that was subjected to extensive to moderate weathering following removal of detritus from the source area. The main controls on the alteration of framework composition and the heavy-mineral assemblage are interpreted as surface weathering, based on moderate Chemical Index of Alteration values and meteoric flushing, and reworking by waves, based on an estimated low amount of feldspar before burial. Thus, the maturation of lower Cambrian quartz arenite on southwestern Baltica can be ascribed to a combination of processes including weathering in the source-rock area, extensive reworking, and early diagenesis. This study also highlights the importance of understanding alteration processes affecting the deposits from source to sink, and to be careful to describe quartz-rich rocks as simply recycled deposits.

scholarly journals Potassium-metasomatism in Anthracite: A Cluster of Geochemical Evidences

2021 ◽  
Author(s):  
Santanu Ghosh ◽  
Anwita Ojha ◽  
Atul Kumar Varma
Keyword(s):  
Source Rock ◽  
Chemical Weathering ◽  
Bituminous Coal ◽  
Climatic Conditions ◽  
Rock Composition ◽  
Thrust Belts ◽  
Chemical Index ◽  
Parent Rocks ◽  
Chemical Index Of Alteration ◽  
The Fourier Transform

Abstract The present study focuses on the inorganic geochemical features of the bituminous coal samples from the Raniganj and the Jharia Basin, as well as the anthracite samples from the Himalayan fold-thrust belts of Sikkim, India. The SiO2 content (48.05 to 65.09 wt% in the ash yield of the bituminous coal samples and 35.92 to 50.11 wt% in the ash yield of the anthracite samples) and the ratio of Al2O3/TiO2 (6.97 to 17.03 in the bituminous coal samples and 10.34 to 20.07 in the anthracite samples) reveal the intermediate igneous source rock composition of the minerals. The ratio of the K2O/Al2O3 in the ash yield of the bituminous coal samples (0.03 to 0.09) may suggest the presence of kaolinite mixed with montmorillonite, while its range in the ash yield of the anthracite samples (0.16 to 0.27) may imply the presence of illite mixed with kaolinite. The chemical index of alteration values may suggest the moderate to strong chemical weathering of the source rock under sub-humid to humid climatic conditions. The plot of the bituminous coal samples in the A-CN-K diagram depicts the traditional weathering trend of parent rocks, but the anthracite samples plot near the illite field and are a bit offset from the weathering trend. This may imply the plausible influences of the potassium-metasomatism at post coalification stages. The Fourier transform infrared spectra further reveal the hydroxyl stretching intensity of the illite in the anthracite samples substantiating the effect of the epigenetic potassium-metasomatism. The decrease in total kaolinite intensity/compound intensity of quartz and feldspar may provide additional evidence towards this epigenetic event.

scholarly journals PETROLOGICAL CHARACTERISTICS OF CLASTIC SEDIMENTARY ROCKS FROM THE ST. BARBARA ORE MINE IN RUDE NEAR SAMOBOR

2021 ◽  
Vol 36 (1) ◽  
pp. 121-135
Author(s):  
Šime Bilić ◽  
Vesnica Garašić
Keyword(s):  
Iron Ore ◽  
Sedimentary Rocks ◽  
Source Rocks ◽  
Chemical Index ◽  
Quartz Arenite ◽  
Petrographic Analyses ◽  
Chemical Index Of Alteration ◽  
Geochemical Analyses ◽  
Clastic Sedimentary ◽  
Very High

In the scope of this research, the petrographic and geochemical analyses of clastic sedimentary rocks from the St. Barbara, copper and iron ore mine in Rude near Samobor, have been made, aiming to classify and determine the provenance and environment of formation of clastic sedimentary rocks, as well as the influence of hydrothermal fluids on their properties. Eight samples were collected in total from different locations in the mine. Six of those samples have been studied in detail. The results showed structural and geochemical variability and uneven hydrothermal alteration intensity in the samples. Based on petrographic analyses, three rocks are classified as sublithoarenite, quartz arenite and quartz greywacke. Three of the samples are classified as ore breccia, ore sandstone, and ore silt-sandstone due to the pronounced hydrothermal alterations and ore mineralisation. Comprehensively, petrographic and geochemical analyses indicate that the source rocks of the investigated clastic sedimentary rocks were felsic (La/Sc = 0.9-6.2; Th/Sc = 1.3-2.4), most probably sedimentary, possibly resedimented rocks. The extent of source rock weathering was very high (Chemical Index of Alteration CIA = 52.1 - 81.3 %) and the geotectonic position of the sedimentary basin was very likely to be at the passive continental margin.

Provenance and geochemical variations across the Ediacaran–Cambrian transition in the Soltanieh Formation, Alborz Mountains, Iran

2018 ◽  
Vol 156 (07) ◽  
pp. 1157-1174 ◽  
Author(s):  
NAJMEH ETEMAD-SAEED ◽  
MAHDI NAJAFI
Keyword(s):  
Chemical Weathering ◽  
Tectonic Setting ◽  
Geochemical Data ◽  
Remarkable Change ◽  
Northern Iran ◽  
Magmatic Arc ◽  
Chemical Index ◽  
Geochemical Variations ◽  
Chemical Index Of Alteration ◽  
Mountain Belts

AbstractThe Soltanieh Formation in the Alborz Mountains of northern Iran is not only a key lithostratigraphic unit for reconstruction of the Iranian geological history, but also a globally outstanding succession to reveal variations in seawater composition across the Precambrian–Cambrian (PC–C) transition. Mineralogical and geochemical data from a continuous stratigraphic record of Lower and Upper Shale members of the Soltanieh Formation are used to define their provenance, tectonic setting as well as geochemical variations during the PC–C transition. The Soltanieh mudrocks are composed of quartz and plagioclase, with minor constituents of illite, chlorite and montmorillonite. The chemical index of alteration, A-CN-K (Al2O3 – CaO + Na2O – K2O) relations, index of compositional variability, and Th/Sc versus Zr/Sc ratios indicate low chemical weathering in source areas, compositionally immature and first-cycle sediments. Immobile trace-element ratios and discrimination diagrams, chondrite-normalized rare Earth element (REE) patterns and negative Eu anomaly, along with low total REE abundances and negligible Ce anomalies, demonstrate that the Soltanieh Formation was mainly derived from proximal felsic-intermediate Cadomian magmatic arc sources and deposited in a continental-arc-related basin on the proto-Tethyan active margin of Gondwana. The palaeoredox indicators exhibit a remarkable change in environmental condition from a suboxic to an oxic state across the PC–C transition from the Kahar Formation to the Upper Shale Member of the Soltanieh Formation. Moreover, a significant upwards increase of P, Ba, and Ca is likely associated with enhanced fluxes of nutrient elements during the PC–C transition, coeval with the building of collisional mountain belts during the amalgamation of Gondwana.

scholarly journals Geochemical and Petrographical Evolution of the Weathering Mantle Derived from Basalt in Bangam Locality (West-Cameroon): Implication in the Bauxitisation Process

2019 ◽  
pp. 1-20
Author(s):  
Taylor Moise Sojien ◽  
Estelle Lionelle Tamto Mamdem ◽  
Armand Sylvain Ludovic Wouatong ◽  
Dieudonne Lucien Bitom Oyono
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Iron Oxides ◽  
Major Elements ◽  
Redox Condition ◽  
Parent Rock ◽  
Negative Anomaly ◽  
Weathering Index ◽  
Chemical Index ◽  
Chemical Index Of Alteration

A petrographical and geochemistry study of weathering mantle derived from the basaltic parent rock (plagioclase, olivine, pyroxene, zircon) has been conducted in the locality of Bangam (West-Cameroon). The weathered profile shows a vertical lithology succession of weathered parent rock, isalteritic clayed domain and superficial duricrust (alloterite). The weathering of basalt started by the formation of “pain d’epices” structure rich in gibbsite, metahalloysite, kaolinite. The geochemistry analysis of major elements indicate that SiO2 (46% -1.33%), K2O (0.84% - 0.01%), Na2O (3.6% -0.01%), MnO (0.3% - 0.04%), P2O5 (1.9% - 0.38%) and CaO (5% -0.02%) decrease from the bottom to the surface, however TiO2 (2.3% - 4.08%) remain constant, Fe2O3 (24.2% - 24,6%) and Al2O3 (14.5% - 45.2%) increase. The different weathering index such as, chemical index of alteration (55% - 99%), index of lateritization (41% - 103.5%) and Ruxton Ratio (0.12 - 3.21) just indicate an evolution of parent rock dominated by an alumina and iron phases under a control of hydrolysis phenomenon as bisialitisation, monosiallitisation and allitisation with the formation of minerals smectites group, kaolinite group gibbsite and iron oxides group. The fractionation patterns of rare earth elements (REE) show a positive and negative anomaly in Cerium and other rare earth elements, one more, the correlation between major, trace and REE prove a link of different pedological horizons developed on the basalt in redox condition.

scholarly journals Loess in eastern equatorial Pangea archives a dusty atmosphere and possible upland glaciation

2020 ◽  
Vol 133 (1-2) ◽  
pp. 379-392 ◽  
Author(s):  
Lily S. Pfeifer ◽  
Gerilyn S. Soreghan ◽  
Stéphane Pochat ◽  
Jean Van Den Driessche
Keyword(s):  
Chemical Weathering ◽  
Ice Age ◽  
Coarse Grained ◽  
Mean Annual Temperature ◽  
Fine Grained ◽  
Chemical Index ◽  
Low Degree ◽  
Low Latitudes ◽  
Chemical Index Of Alteration ◽  
Unique Distribution

Abstract Carboniferous–Permian strata in basins within the Central Pangean Mountains in France archive regional paleoequatorial climate during a unique interval in geological history (Pangea assembly, ice-age collapse, megamonsoon inception). The voluminous (∼1.5 km) succession of exclusively fine-grained red beds that comprises the Permian Salagou Formation (Lodève Basin, France) has long been interpreted to record either lacustrine or fluvial deposition, primarily based on a local emphasis of subaqueous features in the upper ∼25% of the section. In contrast, data presented here indicate that the lower-middle Salagou Formation is dominated by up to 15-m-thick beds of internally massive red mudstone with abundant pedogenic features (microscale) and no evidence of channeling. Up-section, limited occurrences of ripple and hummocky cross-stratification, and mudcracks record the intermittent influence of shallow water, but with no channeling nor units with grain sizes exceeding coarse silt. These data suggest that the most parsimonious interpretation for the Salagou Formation involves eolian transport of the sediment and ultimate deposition as loess in shallow, ephemeral lacustrine environments. Provenance analyses of the Salagou Formation indicate coarse-grained protoliths and, together with geochemical proxies (chemical index of alteration [CIA] and τNa) that correspond respectively to a low degree of chemical weathering and a mean annual temperature of ∼4 °C, suggest that silt generation in this case is most consistent with cold-weathering (glacial and associated periglacial) processes in the Variscan highlands. Together with previous studies that detailed voluminous Permian loess in western equatorial Pangea, this work shows a globally unique distribution of dust at low latitudes that can be linked either directly to glaciated alpine terranes or to reworked and deflated deposits of other types (e.g., fluvial outwash) where fine-grained material was originally generated from glacial grinding in alpine systems. These results further support a revised model for early Permian climate, in which extratropical ice sheets coexisted with a semiarid tropics that may have hosted significant ice at moderate elevation.

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