scholarly journals Tectonic Setting and Provenance of Eocene Sandstones of Disang Group, Tirap District, Arunachal Pradesh

2021 ◽  
Vol 38 (1) ◽  
pp. 5-12
Author(s):  
Bijit Kumar Gogoi ◽  
R K Sarmah
Keyword(s):  
Tectonic Setting ◽  
Active Continental Margin ◽  
Mafic Rock ◽  
Metamorphic Rocks ◽  
Rare Occurrence ◽  
Arunachal Pradesh ◽  
Plagioclase Feldspar ◽  
Rock Fragments ◽  
Minor Elements ◽  
Petrographic Study

The petrographic study of sandstone belonging to Disang Group of Eocene age shows that quartz and rock fragments are the main constituents among the framework grains. Feldspar percentage is low whereas plagioclase feldspar is dominant with the rare occurrence of K-feldspar. XRF-analysis reveals that SiO2, AI2O3, Fe2O3, MnO, TiO2, Na2O, K2O, CaO, MgO and P2O5 are the major and minor elements. SiO2 constitutes the major proportion of the oxides in the sediments. The study reveals that the provenance of these sandstones is mainly the igneous and metamorphic rocks, and the tectonic setting was an active continental margin. The presence of higher content of chert and mafic rock fragments points towards the ophiolite zone as a provenance. Detritus were possibly derived from the uplifted fold thrust belt of the Myanmar’s landmass with subordinate contribution from the Mishmi Hills region lying to the northeast of the study area.

scholarly journals Provenance analysis and tectonic setting of the Triassic clastic deposits in Western Chukotka, Northeast Russia

2009 ◽  
Vol 4 ◽  
pp. 177-200 ◽  
Author(s):  
M. I. Tuchkova ◽  
S. Sokolov ◽  
I. R. Kravchenko-Berezhnoy
Keyword(s):  
Middle Triassic ◽  
Tectonic Setting ◽  
Upper Triassic ◽  
Metamorphic Rocks ◽  
Lower Grade ◽  
Provenance Analysis ◽  
Northeast Russia ◽  
Rock Fragments ◽  
Facies Associations ◽  
Petrographic Study

Abstract. The study area is part of the Anyui subterrane of the Chukotka microplate, a key element in the evolution of the Amerasia Basin, located in Western Chukotka, Northeast Russia. The subterrane contains variably deformed, folded and cleaved rhythmic Triassic terrigenous deposits which represent the youngest stage of widespread marine deposition which form three different complexes: Lower-Middle Triassic, Upper Triassic (Carnian) and Upper Triassic (Norian). All of the complexes are represented by rhythmic interbeds of sandstone, siltstone and mudstone. Macrofaunas are not numerous, and in some cases deposits are dated by analogy to, or by their relationship with, other units dated with macrofaunas. The deposits are composed of pelagic sediments, low-density flows, high-density flows, and shelf facies associations suggesting that sedimentation was controlled by deltaic progradation on a continental shelf and subsequent submarine fan sedimentation at the base of the continental slope. Petrographic study of the mineral composition indicates that the sandstones are lithic arenites. Although the Triassic sandstones appear similar in outcrop and by classification, the constituent rock fragments are of diverse lithologies, and change in composition from lower grade metamorphic rocks in the Lower-Middle Triassic to higher grade metamorphic rocks in the Upper Triassic. This change suggests that the Triassic deposits represent an unroofing sequence as the source of the clastic material came from more deeply buried rocks with time.

Early Cretaceous redbeds from the Minle Basin, Hexi Corridor, northwest China: Mineralogy and geochemistry implications for paleoweathering, provenance, and tectonic settings

2019 ◽  
Vol 7 (2) ◽  
pp. T525-T545
Author(s):  
Yaxiong Sun ◽  
Wenlong Ding ◽  
Yang Gu ◽  
Gang Zhao ◽  
Siyu Shi ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Lower Cretaceous ◽  
Chemical Weathering ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Northwest China ◽  
Hexi Corridor ◽  
Sediment Supply ◽  
Compositional Variation ◽  
Tectonic Settings

Redbeds with a large thickness in the lower Cretaceous record abundant geologic information in the Minle Basin. We have conducted the paleoweathering conditions, provenance, and tectonic settings based on mineralogy and geochemistry. Our results indicate that mudstone samples are characterized by abundant illite with negligible amounts of K-feldspars and analcime. The lower part of the lower Cretaceous is rich in quartz, whereas the upper part is dominated by dolomite and analcime. We suggest that this is caused by the decreasing input of the clastic influx during the middle-late early Cretaceous. High index of compositional variation values (average 1.33) indicate first-cycle sediment supply, suggesting an overall compositional immaturity and short-distance transportation. These characteristics are consistent with an active regional extension tectonic setting. The [Formula: see text] system ([Formula: see text];[Formula: see text];[Formula: see text]) and Th/U versus Th consistently reveal that the lower Cretaceous experienced a positive gradient in chemical weathering from young to old formations. Although the patterns of trace elements in three formations of the lower Cretaceous are different, those of the rare earth elements (REEs) tend to be consistent. The significant enrichment of light REEs, heavy REEs fractionation, and distinctive negative Eu anomalies suggest derivation from an old, upper continental crust composed of predominantly felsic sediments. This interpretation is supported by several discrimination diagrams such as titanium dioxide-nickel ([Formula: see text]), which shows the characteristics of immature recycled sediments. A few sensitive elements, ratios, and normalized REE patterns indicate a provenance of an active continental margin and a continental island arc (CIA). The La-Th-Sc, Th-Co-Zr/10, and Th-Sc-Zr/10 discrimination plots further confirm the CIA signature. Thus, we conclude that the early Cretaceous redbeds in the Minle Basin, Hexi Corridor, were deposited in a dustpan-shaped half-graben basin in a CIA setting when northwest China was influenced by intense regional extension.

scholarly journals Provenance Studies of Sandstone Facies Exposed Near Igbile Southwestern Nigeria: Petrographic and Geochemical Approach

2014 ◽  
Vol 6 (2) ◽  
pp. 47 ◽  
Author(s):  
Ikhane P. R. ◽  
Akintola A. I. ◽  
Bankole S. I. ◽  
Oyinboade Y. T.
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Inductively Coupled Plasma ◽  
Tectonic Setting ◽  
Source Area ◽  
Rock Fragment ◽  
Petrographic Analysis ◽  
Humid Climate ◽  
Southwestern Nigeria ◽  
Plagioclase Feldspar

The petrography, as well as the major, trace and rare earth element compositions of ten (10) sandstone samples of Maastrichtian Afowo Formation exposed near Igbile, Southwestern Nigeria, have been investigated to determine their provenance, source area weathering conditions, paleoclimate and tectonic setting using petrographic analysis and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). Results of the petrographic analysis revealed that quartz is the most dominant detrital mineral with (86%) followed by weathered plagioclase feldspar (5.10%) and rock fragments (10.9%). The quartz grain is sub-angular to sub-rounded in shape and the sandstones were classified as quartz arenites, sublitharenites and subarkoses based on framework composition of quartz, feldspar and rock fragment plots. This suggests a recycled orogen source for the sandstones and deposition in a humid climate, evidenced by the weathered feldspars. Eleven (11) major, seventeen (17) trace and fourteen (14) rare earth elements were obtained from the geochemical analysis. The major elements values range in concentration from 0.01%–81.39% with SiO2 being the dominant oxide followed by Al2O3 and Fe2O3 constituting over 95% of the major oxides; K2O, TiO2, Na2O, CaO, MgO and P2O5 made up the remaining 5%. The average ratio of SiO2/Al2O3 valued 4.31 for the sandstone is appreciably high indicating that it has been heavily weathered. The trace elements range in concentration from 0.2 ppm–1651.2 ppm with Zr being the most dominant element an indication of orogenic recycling. The rare earth elements range in concentration from 0.01 ppm–163.7 ppm with Ce having the highest concentration, depicting that the sandstones were deposited in an oxidizing environment. Also, the trace element relationship illustrated from the spider plot shows chemical coherence and uniformity of the sandstones. The chondrite normalized rare earth elements (REE) plot shows enrichment in the Light REE over the heavy REE for the sediment with strong negative Eu anomaly values between (0.57–0.69) suggesting a felsic provenance derived from upper continental crust for the sandstones.

scholarly journals Neoproterozoic Nafun Group Sediments from Oman Affected by an Active Continental Margin

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 511
Author(s):  
Liang Yue ◽  
Veerle Vandeginste
Keyword(s):  
Continental Margin ◽  
Water Oxidation ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Trace Element Analysis ◽  
Deep Ocean ◽  
Geochemical Data ◽  
Ocean Water ◽  
Element Analysis ◽  
Deep Ocean Water

The Neoproterozoic era is a time of major environmental change in Earth history. The Ediacaran period (635–541 Ma), the uppermost division of Precambrian time, is characterized by the remarkable Shuram excursion (largest C isotope negative excursion), a deep ocean water oxidation event, and Ediacaran biota. The Nafun Group of Oman provides a well-preserved and mostly continuous section of an Ediacaran succession. Based on geochemical data from the Nafun Group, the Shuram excursion (SE) and deep ocean oxidation hypotheses were proposed. Now, we sampled this section at high stratigraphic resolution, and present here the petrographical and geochemical analysis of the Khufai, Shuram and Buah Formations. The major and trace element analysis of shales from the Shuram Formation indicates that northern Oman was an active continental margin environment in Neoproterozoic times. The provenance of the Shuram Formation was primarily mafic and intermediate igneous rocks. With the unsteady tectonic setting, the development of the Nafun Group was influenced by hydrothermal supply and volcaniclastic input. Based on the V/Cr and U/Th ratio of the samples from the Nafun Group, our study reveals the transition of the ocean water redox environment, which is connected to the rise and fall of the Ediacaran biota. Our study constrains the tectonic setting of northern Oman and the petrography and geochemical data from the Nafun Group for the hydrothermal and volcaniclastic supply. Thus, our study acknowledges more factors for the explanation of the Ediacaran conundrums.

Geochemistry and origin of Mesoproterozoic metavolcanic rocks from Fisher Massif, Prince Charles Mountains, East Antarctica

1996 ◽  
Vol 8 (1) ◽  
pp. 85-104 ◽  
Author(s):  
E. V. Mikhalsky ◽  
J. W. Sheraton ◽  
A. A. Laiba ◽  
B. V. Beliatsky
Keyword(s):  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Granulite Facies ◽  
Island Arc ◽  
Crustal Component ◽  
Basaltic Rocks ◽  
Metavolcanic Rocks ◽  
High K ◽  
Low K

Fisher Massif consists of Mesoproterozoic (c. 1300 Ma) lower amphibolite-facies metavolcanic rocks and associated metasediments, intruded by a variety of subvolcanic and plutonic bodies (gabbro to granite). It differs in both composition and metamorphic grade from the rest of the northern Prince Charles Mountains, which were metamorphosed to granulite facies about 1000 m.y. ago. The metavolcanic rocks consist mainly of basalt, but basaltic andesite, andesite, and more felsic rocks (dacite, rhyodacite, and rhyolite) are also common. Most of the basaltic rocks have compositions similar to low-K island arc tholeiites, but some are relatively Nb-rich and more akin to P-MORB. Intermediate to felsic medium to high-K volcanic rocks, which appear to postdate the basaltic succession, have calc-alkaline affinities and probably include a significant crustal component. On the present data, an active continental margin with associated island arc was the most likely tectonic setting for generation of the Fisher Massif volcanic rocks.

Petrography and geochemistry of the siliciclastic Araba Formation (Cambrian), east Sinai, Egypt: implications for provenance, tectonic setting and source weathering

2015 ◽  
Vol 154 (1) ◽  
pp. 1-23 ◽  
Author(s):  
HOSSAM A. TAWFIK ◽  
IBRAHIM M. GHANDOUR ◽  
WATARU MAEJIMA ◽  
JOHN S. ARMSTRONG-ALTRIN ◽  
ABDEL-MONEM T. ABDEL-HAMEED
Keyword(s):  
Tectonic Setting ◽  
Source Area ◽  
Xrd Analysis ◽  
Climatic Conditions ◽  
Source Rocks ◽  
Northern Margin ◽  
Rock Fragments ◽  
Geochemical Parameters ◽  
Clastic Sediments ◽  
Chemical Index

AbstractCombined petrographic and geochemical methods are utilized to investigate the provenance, tectonic setting, palaeo-weathering and climatic conditions of the Cambrian Araba clastic sediments of NE Egypt. The ~ 60 m thick Araba Formation consists predominantly of sandstone and mudstone interbedded with conglomerate. Petrographically the Araba sandstones are mostly sub-mature and classified as subarkoses with an average framework composition of Q80F14L6. The framework components are dominated by monocrystalline quartz with subordinate K-feldspar, together with volcanic and granitic rock fragments. XRD analysis demonstrated that clay minerals comprise mixed-layer illite/smectite (I/S), illite and smectite, with minor kaolinite. Diagenetic features of the sandstone include mechanical infiltration of clay, mechanical and chemical compaction, cementation, dissolution and replacement of feldspars by carbonate cements and clays. The modal composition and geochemical parameters (e.g. Cr/V, Y/Ni, Th/Co and Cr/Th ratios) of the sandstones and mudstones indicate that they were derived from felsic source rocks, probably from the crystalline basement of the northern fringe of the Arabian–Nubian Shield. The study reveals a collisional tectonic setting for the sediments of the Araba Formation. Palaeo-weathering indices such as the chemical index of alteration (CIA), chemical index of weathering (CIW) and plagioclase index of alteration (PIA) of the clastic sediments suggest that the source area was moderately chemically weathered. On the northern margin of Gondwana, early Palaeozoic weathering occurred under fluctuating climatic conditions.

Chapter 3 Archean (>2.6 Ga) and Paleoproterozoic (2.5–1.8 Ga), pre- and syn-orogenic magmatism, sedimentation and mineralization in the Norrbotten and Överkalix lithotectonic units, Svecokarelian orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 27-81 ◽  
Author(s):  
Stefan Bergman ◽  
Pär Weihed
Keyword(s):  
Variable Temperature ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Ductile Deformation ◽  
Fe Oxide ◽  
Ductile Shear Zones ◽  
Three Stages ◽  
Felsic Volcanic

AbstractTwo lithotectonic units (the Norrbotten and Överkalix units) occur inside the Paleoproterozoic (2.0–1.8 Ga) Svecokarelian orogen in northernmost Sweden. Archean (2.8–2.6 Ga and possibly older) basement, affected by a relict Neoarchean tectonometamorphic event, and early Paleoproterozoic (2.5–2.0 Ga) cover rocks constitute the pre-orogenic components in the orogen that are unique in Sweden. Siliciclastic sedimentary rocks, predominantly felsic volcanic rocks, and both spatially and temporally linked intrusive rock suites, deposited and emplaced at 1.9–1.8 Ga, form the syn-orogenic component. These magmatic suites evolved from magnesian and calc-alkaline to alkali–calcic compositions to ferroan and alkali–calcic varieties in a subduction-related tectonic setting. Apatite–Fe oxide, including the world's two largest underground Fe ore mines (Kiruna and Malmberget), skarn-related Fe oxide, base metal sulphide, and epigenetic Cu–Au and Au deposits occur in the Norrbotten lithotectonic unit. Low- to medium-pressure and variable temperature metamorphic conditions and polyphase Svecokarelian ductile deformation prevailed. The general northwesterly or north-northeasterly structural grain is controlled by ductile shear zones. The Paleotectonic evolution after the Neoarchean involved three stages: (1) intracratonic rifting prior to 2.0 Ga; (2) tectonic juxtaposition of the lithotectonic units during crustal shortening prior to 1.89 Ga; and (3) accretionary tectonic evolution along an active continental margin at 1.9–1.8 Ga.

scholarly journals Geochemistry of the Um Had Plutonites, Central Eastern Desert, Egypt: Implications for Magma Evolution, and Tectonic Setting

2014 ◽  
Vol 6 (2) ◽  
pp. 36 ◽  
Author(s):  
Nedal Qaoud
Keyword(s):  
Tectonic Setting ◽  
Active Continental Margin ◽  
Eastern Desert ◽  
Island Arc ◽  
Water Vapour Pressure ◽  
Calc Alkaline ◽  
Magma Evolution ◽  
Basement Complex ◽  
Central Eastern Desert ◽  
Pan African

Geochemistry of gabbroid and granitoid plutonites from the Um Had area indicates island arc subalkaline basic magma with tholeiitic affinity and calc-alkaline, metaluminous and slightly peraluminous magma, respectively. Although different in age both plutonite types were emplaced under compressional regime, where subduction-related environment was dominant. They were formed under relatively low to moderate water-vapour pressure (1–5 k-bars) at moderate depths (20–30 km). Biotite granites were formed at a relatively high temperature range (800–840 °C), while biotite-muscovite granites were formed under relatively moderate temperature conditions (760–800 °C). These two units may represent evolution from island arc to active continental margin. It is suggested that island arc gabbros might have sourced the late subduction-related calc-alkaline granitoids during the waning stages of the pan-African orogeny. The I-type nature of the investigated plutonites in the study area and elsewhere suggests the juvenile character of the basement complex of the Eastern Desert of Egypt.

Geochemistry and zircon U–Pb–Hf isotopes of the Mante Aobao granite porphyry at East Ujimqin Banner, Inner Mongolia: implications for petrogenesis and tectonic setting

2019 ◽  
Vol 157 (7) ◽  
pp. 1068-1086
Author(s):  
Fei Hu ◽  
Wei Huang ◽  
Zeli Yang ◽  
Simon A. Wilde ◽  
Harald Furnes ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Saturation Index ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Late Ordovician ◽  
Granite Porphyry ◽  
Hf Isotopes ◽  
Margin Setting ◽  
Juvenile Crust ◽  
Early Palaeozoic

AbstractWe present detailed petrography, geochemistry and zircon U–Pb–Hf isotopes of the Mante Aobao granite porphyry in East Ujimqin Banner, Inner Mongolia, with the aim of determining its age and petrogenesis, important for understanding the early Palaeozoic tectonic evolution of the Xing’an–Mongolian Orogenic Belt. The Mante Aobao granite porphyry consists of plagioclase, quartz and minor biotite, but without amphibole. Zircon U–Pb analyses yield ages of 450 ± 1 Ma and 445 ± 2 Ma for the granite porphyry, indicating that it formed during Late Ordovician time. The granite porphyry is metaluminous to slightly peraluminous (aluminous saturation index A/CNK = 0.98–1.11) with high SiO2, K2O and Na2O concentrations and differentiation index (DI = 85–90). Chondrite-normalized rare earth element (REE) patterns display enrichment of light REEs (LREEs) with high ratios of (La/Yb)N and negative Eu anomalies. In the mantle-normalized multi-element variation diagrams, all samples are characterized by depletions of high-field-strength elements (HFSEs; Nb, Ta and Ti) and enrichments of large-ion lithophiles (LILEs; Rb, Th, U and K). These geochemical features indicate that the granite porphyry is a highly fractionated I-type granite and formed in a subduction-related setting. Zircon grains have positive εHf(t) values of +9.2 to +11.2, and TDM2(Hf) ages of 691–821 Ma, suggesting that the granite porphyry was generated by partial melting of Neoproterozoic juvenile crust with involvement of fractional crystallization during magmatic evolution. It is likely that underplating of mantle-derived magmas during Late Ordovician time provided the necessary heat to partially melt this juvenile crust. Combined with the regional geological data, we infer that the Mante Aobao granite porphyry was emplaced in an active continental margin setting that was probably related to the northwards subduction of the Paleo-Asian Plate beneath the South Mongolian Terrane along the Sonid Zuoqi–Xilinhot axis.

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