scholarly journals Evolution of Syenite Magmas: Insights from the Geology, Geochemistry and O-Nd Isotopic Characteristics of the Ordovician Saibar Intrusion, Altai-Sayan Area, Russia

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 473
Author(s):  
Alexander A. Vorontsov ◽  
Andrey E. Izoh ◽  
Vladimir V. Yarmolyuk ◽  
Tatyana Y. Komaritsyna ◽  
Anatoly V. Nikiforov ◽  
...  
Keyword(s):  
Primitive Mantle ◽  
Rock Composition ◽  
Zircon Age ◽  
Nd Isotope ◽  
Rare Elements ◽  
Incompatible Elements ◽  
Marginal Part ◽  
Mafic Magmas ◽  
Intrusive Suite ◽  
Insight Into

In this paper, we provide insight into the evolution of syenite magmas based on geological data and petrographic, geochemical, and O-Nd isotope parameters of rocks of the Saibar intrusion located within the Minusinsk Trough, Altay-Sayan area. The intrusive suite includes predominant syenites, few bodies of melanocratic and leucocratic nepheline syenites (foyaites), and granites. In addition, dykes of granites and mafic rocks are present. The U-Pb zircon age from the melanocratic foyaites was determined to be 457 ± 27 Ma. Examined rocks show fractionated light rare earth element patterns, normalized to chondrite, with (La/Sm)n varying from 4 to 9, and a weakly fractionated distribution of medium and heavy rare elements, with (Dy/Yb)n from 0.35 to 1.23 and (Sm/Yb)n from 0.63 to 2.62. The spidergram normalized to the primitive mantle shows negative Ba, Sr, Nb, Ta, Ti, and Eu anomalies (Eu* = 0.48–0.60) and positive Rb, Th, and U anomalies. The δ18O values vary within 6.3 to 10.2‰, and εNd(t) from +4.1 to +5.0. We observe gradual transitions from syenites to foyaites. Assimilation by syenite magma of the host carbonate rocks was followed to transition from silica-saturated to silica-undersaturated conditions and removal of anorthite from the melt, which then led to nepheline. Granites of the main phase show depleted lithophile incompatible elements in comparison with syenites and foyaites. They originate via interaction of magmas at the marginal part (endocontact zone) of the intrusion, corresponding to north contact of the granites with the host felsic rocks. In comparison, the rock composition of granite dykes is enriched in lithophile incompatible elements, except for Zr, Hf, and Ti. These rocks are formed due to the differentiation of syenite magma without a significant effect of host rock assimilation. Mantle magmas must be used as parent magmas for syenites based on analysis of the formation model of other alkaline intrusions, which are similar in age to the Saibar intrusion. In the line of syenite intrusions of the Altai-Sayan province, the Saibar intrusion is no exception, and its origin is related to the evolution of mafic magmas that arose during the melting of the mantle under the influence of a mantle plume.

The tectonic setting of the eastern margin of the Sino-Korean Block inferred from detrital zircon U–Pb age and Nd isotope composition of the Pyeongan Supergroup (upper Palaeozoic – Lower Triassic), Korea

2017 ◽  
Vol 156 (3) ◽  
pp. 471-484 ◽  
Author(s):  
MUN GI KIM ◽  
YONG IL LEE ◽  
TAEJIN CHOI ◽  
YUJI ORIHASHI
Keyword(s):  
Detrital Zircon ◽  
Isotope Composition ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Lower Triassic ◽  
Zircon Age ◽  
Nd Isotope ◽  
Eastern Margin ◽  
Late Palaeozoic ◽  
Nd Isotope Composition

AbstractThe upper Palaeozoic succession (Pyeongan Supergroup) in central eastern Korea is well correlated with the equivalent successions distributed in North China, suggestive of the Korean upper Palaeozoic being part of the Sino-Korean Block. Detrital zircon U–Pb ages and Sm–Nd isotope compositions of the Pyeongan Supergroup in the Samcheok coalfield of the Taebaeksan Basin were analysed. A single predominant zircon age peak at c. 1.9 Ga (> 70%) is marked in all sedimentary units, followed by varying amounts of minor late Palaeozoic grains (up to 30%). The rarity of Meso- to Neoproterozoic- and Silurian-aged zircons confirms that sediment influx from the South China and Qinling blocks was insignificant. The 2.0–1.8 Ga-dominated zircon age pattern and the Nd isotope composition (average εNd(0) = −15.5±4.0) of the Pyeongan Supergroup most closely reflect the signature of the Yeongnam Massif basements, which supports a previous hypothesis that the Pyeongan Supergroup was mostly derived from a palaeo-orogen located to the east–southeast. Relatively higher εNd(0) values (> −10.1) in the lowermost and the upper parts of the succession are closely matched by the increased occurrence of syn-depositional-aged zircons, which indicates considerable mixing of juvenile materials at c. 320 Ma and 260 Ma. Both arc-related magmatic events are interpreted to have been related to oceanic subduction, suggesting that the eastern margin of the Sino-Korean Block was an active continental margin during late Palaeozoic times.

scholarly journals Supplemental Material: Apatite fingerprints on the magmatic-hydrothermal evolution of the Daheishan giant porphyry Mo deposit, NE China

2021 ◽  
Author(s):  
Pan Qu ◽  
Wubin Yang
Keyword(s):  
Wall Rock ◽  
Major And Trace Elements ◽  
Primitive Mantle ◽  
Ne China ◽  
Pb Isotope ◽  
Nd Isotope ◽  
Isotope Data ◽  
Porphyry Mo Deposit ◽  
Spider Diagrams ◽  
Ree Patterns

Figure S1: Harker diagrams illustrating major elemental variations of the porphyry and wall rock. QGP—Qiancuoluo granodioritic porphyry; QBG—Qiancuoluo biotite granodiorite; Figure S2: (a) Chondrite-normalized REE patterns and (b) primitive mantle (PM)-normalized spider diagrams of the porphyry and wall rock. Normalizing values are taken from S. Sun and McDonough (1989); Table S1: Whole-rock major and trace element compositions of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG) granites; Table S2: Whole-rock Sr-Nd compositions of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S3: Apatite major and trace elements (ppm) of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S4: Apatite Sr and Nd isotope data of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG); Table S5: Apatite U-Pb isotope data of the Qiancuoluo granodioritic porphyry (QGP) and Qiancuoluo biotite granodiorite (QBG).

scholarly journals Mg-Fe-RICH AMPHIBOLES ASSOCIATED TO PYROCLASTICS FROM SANTORINI ISLAND, SOUTH AEGEAN SEA VOLCANIC ARC, GREECE

2007 ◽  
Vol 40 (2) ◽  
pp. 851
Author(s):  
K. Kitsopoulos
Keyword(s):  
Water Content ◽  
Volcanic Activity ◽  
Volcanic Rocks ◽  
Aegean Sea ◽  
Primitive Mantle ◽  
Mineral Phase ◽  
Volcanic Arc ◽  
Mineral Phases ◽  
Mafic Magmas ◽  
Silicic Magmas

Amphibole bearing volcanic products in Santorini are restricted to the early volcanic activity expressed in the Akrotiri peninsula. This fact distinguishes these early products from the rest of the volcanic rocks of Santorini. The Fe-Mg-rich mineral phases, associated to the Akrotiri silicic pyroclastics which were analysed can be classified as Mg-Fe rich type of amphibole. This type of amphibole has not been reported before in volcanic rocL· from the South Aegean Volcanic Arcr. The presence of such a high Fe-Mg mineral phase in silicic pyroclastics in Santorini is constant with the involvement of primitive, mantle derived, mafic magmas, with some considerable water content, and which have been differentiated, before they are mixed with more silicic magmas at a shallower crustal level.

Interpreting magmatic processes from accessory phases: titanite—a small-scale recorder of large-scale processes

2000 ◽  
Vol 91 (1-2) ◽  
pp. 257-267 ◽  
Author(s):  
Philip Piccoli ◽  
Philip Candela ◽  
Mark Rivers
Keyword(s):  
Sierra Nevada ◽  
Large Scale ◽  
Functional Dependence ◽  
Trace Element Analysis ◽  
Quartz Diorite ◽  
Small Scale ◽  
Element Analysis ◽  
General Behaviour ◽  
Rock Composition ◽  
Intrusive Suite

In this study we examined variations in ore and other trace-metal concentrations in titanite, a ubiquitous product of magmatic (and subsequent sub-solidus) crystallisation in oxidised silicic magmas. Accessory titanite occurs in the Tuolumne Intrusive Suite (TIS), Sierra Nevada Batholith, as euhedral to anhedral, poikilitic, or interstitial grains. Zoned crystals of titanite were analysed by electron microprobe and synchrotron X-ray fluorescence for major and trace elements. Backscatter electron images reveal zoning, with bright areas correlating positively with total REE concentrations. REE concentrations generally decrease toward the edge of titanite crystals; however, some crystals are reversely zoned, and others exhibit oscillatory or patchy zoning; some grains contain discrete anhedral cores. Most elements in magmatic titanite decrease in concentration towards crystal rims, independent of host rock composition.At least one major reduction event in the magma chamber(s) transiently stabilised ilmenite, now present only as inclusions in titanite, and resulted in a reduction in the REE concentration in titanite. We suggest the hypothesis that the reduction in the REE concentration in these zones is due to the diminished activity of the (REE)Fe3+Ca−1Ti−1exchange component; however, the scatter in the data, together with the operation of other exchange vectors for Fe and Al, did not allow us to test this hypothesis herein. Secondary (i.e. sub solidus, hydrothermal) titanite can be recognised on the basis of its chemistry, sometimes by its anhedral form, and by its position as an alteration rim around primary magmatic phases; however, secondary titanite growth on primary titanite crystals may be harder to discern. Secondary titanite rims on magnetite contain higher Cr, Zr and Mo, and lower REE, relative to magmatic titanite. U/Th ratios increase toward the rim of most titanite grains; however, Th decreases in concentration from core to rim. This is due, most likely, to complications resulting from the coupled substitutions necessary for replacement of Ca by tetravalent Th; factors of this sort are commonly overlooked in trace element analysis.The analysed titanites are from rocks of the normally zoned TIS which ranges in87Sr/86Sri, from 0·7059 (tonalite and quartz-diorite) to 0·7066 (granite). Many element ratios in the titanites exhibit little to no functional dependence on87Sr/86Sri. However, log Mo/W increases with increasing87Sr/86Sri, of the host unit from the equigranular quartz-diorite and tonalite, to the interior granodiorites, possibly reflecting the greater crustal contribution to the interior, more felsic units. Neither Mo nor W increase significantly from core to rim in titanite. If these trends are indicative of the general behaviour of these elements duringin-situfractionation, then these data suggest that Mo and W are not strongly incompatible, and indeed may behave compatibly, in some titaniteand magnetite-bearing granodioritic magmas.

Age and tectonic significance of the Lassiter Coast Intrusive Suite, Eastern Ellsworth Land, Antarctic Peninsula

2005 ◽  
Vol 17 (3) ◽  
pp. 443-452 ◽  
Author(s):  
M.J. FLOWERDEW ◽  
I.L. MILLAR ◽  
A.P.M. VAUGHAN ◽  
R.J. PANKHURST
Keyword(s):  
Isotope Composition ◽  
Geographical Area ◽  
Nd Isotope ◽  
The North ◽  
The Pacific ◽  
Depleted Mantle ◽  
Major Fault ◽  
Similar Character ◽  
Pacific Margin ◽  
Intrusive Suite

Depleted mantle model ages derived from granitoids of the Lassiter Coast Intrusive Suite, sampled over a wide geographical area in eastern Ellsworth Land, Antarctica, cluster between 1000 Ma and 1200 Ma and suggest involvement of Proterozoic crust in the petrogenesis of the suite. Ion-microprobe U–Pb zircon analyses from a small intrusion at Mount Harry, situated at the English Coast, yield a concordant age of 105.2 ± 1.1 Ma, consistent with published ages from other parts of the Lassiter Coast Intrusive Suite. Significant variation in the Sr and Nd isotope composition of the granitoids, along the extrapolation of the Eastern Palmer Land Shear Zone (a proposed terrane boundary) located close to the English Coast, is not evident. However, the isotope signature at the English Coast is more homogeneous than the Lassiter Coast; this variation may relate to geographical proximity to the Pacific margin during intrusion, may reflect subtle changes in basement with a broadly similar character across the proposed terrane boundary, or suggest that any major fault structure is located further to the north, with implications for the kinematics of regional mid-Cretaceous transpression.

Nd isotope chemistry of Tertiary igneous rocks from Arran, Scotland: implications for magma evolution and crustal structure

1994 ◽  
Vol 131 (3) ◽  
pp. 329-333 ◽  
Author(s):  
A. P. Dickin
Keyword(s):  
Crustal Structure ◽  
Granulite Facies ◽  
Igneous Rocks ◽  
Primitive Mantle ◽  
Magmatic Differentiation ◽  
Magma Evolution ◽  
Quartz Porphyry ◽  
Nd Isotope ◽  
Isotopic Signatures ◽  
Geochemical Evidence

AbstractThe geochemistry of Tertiary igneous rocks from Arran, western Scotland, provides a probe for the structure of the crust in the region of the Highland Boundary Fault (HBF). New Nd isotope data, coupled with other geochemical evidence, point to variable contamination of primitive mantle-derived magmas during magmatic differentiation in the crust. Two different isotopic contamination trends are seen. The northern granite was generated by contamination of basic differentiates by crust resembling exposed Dalradian units. Data for the central granite, and several other minor intrusions from south of the HBF, trend towards the reported isotopic signatures of granulite-facies xenoliths from the Midland Valley. However, quartz porphyry intrusions in the south of the island are compositionally similar to the nothern granite, and were probably intruded southwards across the HBF in dykes. Hence the isotopic signatures of the Tertiary intrusions reflect the different character of the crustal units on either side of the fault.

Volcanism from fissure zones and the Caldeira central volcano of Faial Island, Azores archipelago: geochemical processes in multiple feeding systems

2013 ◽  
Vol 150 (3) ◽  
pp. 536-555 ◽  
Author(s):  
VITTORIO ZANON ◽  
ULRICH KUEPPERS ◽  
JOSÉ MANUEL PACHECO ◽  
INÊS CRUZ
Keyword(s):  
Fractional Crystallization ◽  
Central Volcano ◽  
Geochemical Processes ◽  
Magma Reservoirs ◽  
Incompatible Elements ◽  
Mantle Sources ◽  
Mafic Magmas ◽  
Multiple Feeding ◽  
Atlantic Area ◽  
Feeding Systems

AbstractMagmas in Faial Island, Azores (Portugal), were mostly erupted from two fissure zones and the Caldeira central volcano during overlapping periods. The fissure zones follow extensional trends oriented WNW and ESE and erupted nepheline- to hypersthene-normative basalts and hawaiites. The Caldeira central volcano builds the central part of the island, which is cut by the fissure zones. Ne-normative basalts show similar high-field-strength element (HFSE) concentrations but higher large ion lithophile element (LILE) concentrations than hy-normative equivalents. Primitive melts were generated by small (3–5%) degrees of partial melting of garnet-bearing peridotite, variably enriched in incompatible elements. Overall, basalts from Faial show relatively higher LILE abundances and LILE/HFSE ratios than those of the other islands of the Azores and of many other volcanoes in the Atlantic area. This feature indicates the existence of chemical heterogeneities in the mantle sources characterized by variable degrees of metasomatism, both at local and regional scales. Hawaiites evolved from basalts through 30–40% fractional crystallization of mafic phases plus some plagioclase, in deep reservoirs, at about 430–425 MPa (~ 15 km). The Caldeira central volcano rocks range from basalts to trachytes. Basalts, produced under similar conditions as fissure basalts, evolved to trachytes through large degrees of polybaric fractional crystallization (100–760 MPa; i.e. ~ 3.6–26 km), involving olivine, clinopyroxene, feldspar and minor quantities of amphibole, biotite, apatite and oxides. In contrast, mafic magmas from the fissure zones were erupted directly onto the surface from magma reservoirs mainly located at the crust–mantle boundary.

Elements of Phonological Interventions for Children With Speech Sound Disorders: The Development of a Taxonomy

2018 ◽  
Vol 27 (3) ◽  
pp. 906-935 ◽  
Author(s):  
Elise Baker ◽  
A. Lynn Williams ◽  
Sharynne McLeod ◽  
Rebecca McCauley
Keyword(s):  
Content Analysis ◽  
Element Concentration ◽  
Speech Sound ◽  
Common Elements ◽  
Speech Sound Disorders ◽  
Empirically Supported ◽  
Rare Elements ◽  
Structural Relationships ◽  
Compare And Contrast ◽  
Insight Into

Purpose Our aim was to develop a taxonomy of elements comprising phonological interventions for children with speech sound disorders. Method We conducted a content analysis of 15 empirically supported phonological interventions to identify and describe intervention elements. Measures of element concentration, flexibility, and distinctiveness were used to compare and contrast interventions. Results Seventy-two intervention elements were identified using a content analysis of intervention descriptions then arranged to form the Phonological Intervention Taxonomy: a hierarchical framework comprising 4 domains, 15 categories, and 9 subcategories. Across interventions, mean element concentration (number of required or optional elements) was 45, with a range of 27 to 59 elements. Mean flexibility of interventions (percentage of elements considered optional out of all elements included in the intervention) was 44%, with a range of 29% to 62%. Distinctiveness of interventions (percentage of an intervention's rare elements and omitted common elements out of all elements included in the intervention [both optional and required]) ranged from 0% to 30%. Conclusions An understanding of the elements that comprise interventions and a taxonomy that describes their structural relationships can provide insight into similarities and differences between interventions, help in the identification of elements that drive treatment effects, and facilitate faithful implementation or intervention modification. Research is needed to distil active elements and identify strategies that best facilitate replication and implementation.

scholarly journals Dynamical geochemistry of the mantle

Solid Earth ◽  
2011 ◽  
Vol 2 (2) ◽  
pp. 159-189 ◽  
Author(s):  
G. F. Davies
Keyword(s):  
Trace Elements ◽  
Oceanic Crust ◽  
Primitive Mantle ◽  
Mantle Heterogeneity ◽  
The Past ◽  
Incompatible Elements ◽  
The Earth ◽  
Depleted Mantle ◽  
Morb Source ◽  
Dynamical Modelling

Abstract. The reconciliation of mantle chemistry with the structure of the mantle inferred from geophysics and dynamical modelling has been a long-standing problem. This paper reviews three main aspects. First, extensions and refinements of dynamical modelling and theory of mantle processing over the past decade. Second, a recent reconsideration of the implications of mantle heterogeneity for melting, melt migration, mantle differentiation and mantle segregation. Third, a recent proposed shift in the primitive chemical baseline of the mantle inferred from observations of non-chondritic 142Nd in the Earth. It seems most issues can now be resolved, except the level of heating required to maintain the mantle's thermal evolution. A reconciliation of refractory trace elements and their isotopes with the dynamical mantle, proposed and given preliminary quantification by Hofmann, White and Christensen, has been strengthened by work over the past decade. The apparent age of lead isotopes and the broad refractory-element differences among and between ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) can now be quantitatively accounted for with some assurance. The association of the least radiogenic helium with relatively depleted sources and their location in the mantle have been enigmatic. The least radiogenic helium samples have recently been recognised as matching the proposed non-chondritic primitive mantle. It has also been proposed recently that noble gases reside in a so-called hybrid pyroxenite assemblage that is the result of melt from fusible pods reacting with surrounding refractory peridotite and refreezing. Hybrid pyroxenite that is off-axis may not remelt and erupt at MORs, so its volatile constituents would recirculate within the mantle. Hybrid pyroxenite is likely to be denser than average mantle, and thus some would tend to settle in the D" zone at the base of the mantle, along with some old subducted oceanic crust. Residence times in D" are longer, so the hybrid pyroxenite there would be less degassed. Plumes would sample both the degassed, enriched old oceanic crust and the gassy, less enriched hybrid pyroxenite and deliver them to OIBs. These findings can account quantitatively for the main He, Ne and Ar isotopic observations. It has been commonly inferred that the MORB source is strongly depleted of incompatible elements. However it has recently been argued that conventional estimates of the MORB source composition fail to take full account of mantle heterogeneity, and in particular focus on an ill-defined "depleted" mantle component while neglecting less common enriched components. Previous estimates have also been tied to the composition of peridotites, but these probably do not reflect the full complement of incompatible elements in the heterogeneous mantle. New estimates that account for enriched mantle components suggest the MORB source complement of incompatibles could be as much as 50–100 % larger than previous estimates. A major difficulty has been the inference that mass balances of incompatible trace elements could only be satisfied if there is a deep enriched layer in the mantle, but the Earth's topography precludes such a layer. The difficulty might be resolved if either the Earth is depleted relative to chondritic or the MORB source is less depleted than previous estimates. Together these factors can certainly resolve the mass balance difficulties.

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