A genetic classification of the tholeiitic and calc-alkaline …
Our results demonstrate that log ratio analysis provides a natural way to parameterise physical processes that give rise to these magma series. Much petrological nomenclature predates …
Our results demonstrate that log ratio analysis provides a natural way to parameterise physical processes that give rise to these magma series. Much petrological nomenclature predates …
The tectonic mechanisms that may trigger a transition from calc-alkaline to alkaline volcanic activity above a subduction zone are enigmatic. We report major/trace elemental and Sr-Nd-Ca isotopic compositions of a suite of magmatic samples from the Miocene Gördes calc-alkaline dacites and the Quaternary Kula alkaline basalts from Western Anatolia, Turkey.
These granitoids can be divided into a high-K calc-alkaline and peraluminous I-type granodiorites, and an alkaline and metaluminous A-type granites, with zircon U–Pb dating indicating that they ...
Basalts form the most important group of volcanic rocks and occur worldwide. Formation, differentiation and eruption of basaltic magmas are closely related to plate tectonics (e.g., Pearce and Cann 1973: see Table 19.1). Experimental investigations in simplified model systems and on natural rocks have contributed to our understanding of the genesis of basaltic …
Alkaline magmatism can occur in different tectonic settings, including convergent margins (i.e., island arcs, continental arcs, and continental collisional zones), divergent plate
The tholeiitic differentiation trend, which is often documented in the volcanic sequences of intra-oceanic arcs, is best reproduced by the LLD of an H 2 O-poor (∼0·5 wt %) …
The high salinity paleolake would become saturated in calcium bicarbonate/carbonate as internally drained NaHCO 3-bearing alkaline waters, formed by physical/chemical weathering of penecontemporaneous basaltic rocks, mix with the CaCl 2-bearing hot brines percolating through the barrier, producing a hybrid brine (2NaHCO 3 + CaCl …
Alkaline magmas are an uncommon but intriguing member of many of the Earth's volcanic arc systems. This peculiar magmatism is generally associated with perturbations to the "normal" tectonic ...
The tectonic environment and genesis of basalt are analyzed through systematic study of the geochemical characteristics of the main, trace and rare earth elements in this area. ... (IV1) intracontinental rift and marginal rift Tholeiitic basalt area; (IV2) intrauterine rift alkaline basalt zone; (IV3) continental tensioning zone (or initial ...
In this study, we utilize mafic tephras collected from Buldir Volcano to address the genesis of strongly calc-alkaline volcanic rocks (those with a low Tholeiitic Index; ≤0·7) in a …
Quick facts and properties. Name: Basalt Rock type: Igneous Origin: Extrusive Texture: Fine-grained or aphanitic with grain sizes less than 1/16 mm but may be porphyritic, vesicular, subophitic, ophitic, or amygdaloidal. Colors: Dark gray, dark green-gray, greenish black to black. Cooling rate or history: Fast on the Earth's surface Chemical composition: Mafic or basic
Calc-alkaline lamprophyres are widely regarded as important probes for unravelling continental-scale geodynamic processes. We present petrographic, mineral chemical, bulk-rock geochemical, and Sr ...
The Matachel "basic volcanism" association with calc-alkaline signature (Group #3 rocks) exhibits no discernible time and/or spatial gaps with respect to the of Low-Ti continental tholeiite outpourings (Groups #1 and #2). The observed calc-alkaline basalt Al 2 O 3 contents
Petrogenesis of Early Carboniferous Alkaline Basalt from the Wusun Mountain: Implications for Tectonic Evolution of the Western Yining Block (NW China) October 2019 Acta Geologica Sinica 95(4)
The Madang Cenozoic sodic alkaline basalt occurred in the eastern margin of the Tibetan Plateau, where is a key tectonic transform region of Tibet, North China, and Yangtze blocks. ... The Madang basalts occurred in the specific tectonic background, they result from partial melting of a mixed asthenospheric mantle reservoir in the western ...
This tectonic episode promoted the Carboniferous (Mississippian and Pennsylvanian) tholeiitic to calc-alkaline magmatism, represented in the Colombian Andes through the tonalite and diorite-gabbro ...
We present a new model for the formation of Plio-Pleistocene alkaline basalts in the central part of the Carpathian-Pannonian region (CPR). Based on the structural hydroxyl …
Alkalis (Na₂O + K₂O): 2-5% - Relatively low compared to other rock types, reflecting the abundance of magnesium and calcium in basalt. Iron oxides (FeO and Fe₂O₃): 5-14% - These oxides contribute to the dark color and give basalt its high density. Calcium oxide (CaO): ~10% - A key component of plagioclase feldspar, a dominant mineral in ...
Although peridotite xenoliths are common in alkaline basalts, it is still unclear whether the chemical compositions of their host rocks have been affected by these mantle fragments and, if so, what processes are involved in this alteration of the host basalts. Here, we document a kind of xenolith‐rich alkaline basalts from the Nanjing basaltic field, eastern China. …
Given the very different isotopic compositions of MOR mantle/basalt compared to subducted sediment, the limited range in isotopic composition of Cascades lavas would demand tight control over the ratio of sediment to MOR mantle/basalt in the genesis of the subduction component if the isotopic composition of the calc-alkaline basalts is as ...
fore, carbonatite, carbonated silicate and alkaline basalt magmas can provide important information on C recy- cling (Amsellem et al., 2020 ; Banerjee et al., 2021 ; Simon, 2022 ).
CALC-ALKALINE ROCK SERIES 689 the "alkali-lime index" (e.g., Baumann and Wätzig, 1997; Drapper and Smith, 1998). Nockolds and Allen (1953, 1954, 1956) sug-
We redefine tholeiitic (TH) and calc-alkaline (CA) magma series based on the THI and use this index to test models for the origin of CA fractionation.
Melt-peridotite reaction is a pivotal mechanism for genesis of continental intraplate alkali basalts. ... The striking similarity of the composition and tectonic distribution of the alkali basalts from eastern China with those of the central ... Eclogite trace in evolution of Late Cenozoic alkaline basalt volcanism on the southwestern flank of ...
The Si-undersaturated strongly alkaline phonolite and the Si-saturated mildly alkaline trachyte can be modelled by fractionation of basanite and basalt, respectively. ... The tectonic evolution of ...
Alkaline basaltic volcanism has been taking place in the Carpathian–Pannonian region since 11 Ma and the last eruptions occurred only at 100–500 ka. It resulted in scattered low-magma volume volcanic fields located mostly at the margins of the Pannonian basin. Many of the basalts have compositions close to those of the primitive magmas and therefore can be …
genesis of alkaline basalt-hosted sapphires was intensively . ... tectonic block within the Rhenohercynian Zone and has . ... between calcium carbonate polymorphs in carbonate inclu-
In this paper, we present major and trace element analyses and radiogenic isotopic compositions for lavas from Newberry Volcano with a focus on the most primitive basalts. A limited number of additional lavas also were …
Major and trace element data on selected basalt types are listed in Table 1.Distribution of Fe, Mg, and Na + K (alkalies) is usually illustrated on an A (alkalies)—F(Fe 2 O 3 + FeO)—M(MgO) diagram. Subalkaline and alkaline basalts show wide variation in Na/K, Fe/Mg ratios and Al 2 O 3 content. Tholeiitic basalts show the characteristic relationship between SiO 2 content and …
Crustal contamination is negligible for both alkaline and tholeiitic basalts according to the following reasons: (1) Mantle xenoliths are observed in the alkaline basalts (Wang et al., 2016), indicating rapid eruption of the magma and short residence time in the crust; (2) The alkaline and tholeiitic basalts all have positive Nb Ta anomalies ...
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