Petrological Features of Korsun'-Novomyrhorod Anorthosite-Rapakivi Granite Pluton

2021 ◽  
Vol 43 (4) ◽  
pp. 25-49
Author(s):  
S.G. KRYVDIK ◽  
O.V. DUBYNA ◽  
P.F. YAKUBENKO
Keyword(s):  
High Alumina ◽  
Crustal Material ◽  
Rapakivi Granite ◽  
Granite Pluton ◽  
Number Of Factors ◽  
Erosion Level ◽  
Granite Magmatism ◽  
Geochemical Studies ◽  
Lower Crustal ◽  
Basic Rocks

The Korsun’-Novomyrhorod pluton is the second after the Korosten one in terms of the scale of Proterozoic (1757-1748 Ma) anorthosite-rapakivi-granite magmatism in the Ukrainian Shield. According to geochronological data, pluton was formed as a result of multiple ascending and crystallization of basic to acidic melts. Differentiation of initial melts because to be responsible for gabbro-anorthosite and monzonites series crystallization. Whereas rapakivi granites, which are predominate in the modern erosion level, were formed from felsic magma not directly related with differentiation of basic melt. In view of the current level of mineralogical research, it is difficult to use modern geobarometry methods to reliably estimate the depth of rocks crystallization. At the same time, a number of factors (absence of volcanic and dike analogues of basic rocks, insignificant distribution of pegmatite bodies, predominance of high-Fe mafic minerals, absence of primary magnetite, etc.) indicate deeper conditions for rocks disclosed by modern erosional cut in comparition to similar Korosten pluton. Therefore, the liquid line of dissent, petrological and mineralogical features of the rocks can be explained by the reducing (low fO2) or abyssal conditions of their formation. It is possible that the deeper conditions of crystallization of parental melt are due to more distinctly developed syenitic trend of evolution with the appearance of high-Fe syenites during final stages. Preliminary data indicate on possibility of vertical layering of gabbro-anorthosite massifs, which manifested by increasing proportion of high-Fe basic rocks with depth. Available isotope-geochemical studies do not provide unambiguous data on regarding reservoirs of primary melts implaying both mantle and mixed mantle-crustal their origin. The evolution of the petrochemical features of basic rocks, in our opinion, is in better agreement with their formation as result of differentiation of the primary high-alumina tholeiitic melt, significantly contaminated by lower crustal material. This determined the subalkaline nature of basic rocks and a significant predominance of norites, in comparition to more typical gabbros, and monzonites. In contrast to the previously proposed hypotheses of the formation of intermediate rocks because of partial melting of felsic rocks by basic intrusions, or mingling of basic and acidic melts, some of petrochemical features and geological position can be satisfactorily explained by their crystallization from the residual melt.

scholarly journals Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

2015 ◽  
Vol 66 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Jozef Vozár ◽  
Ján Spišiak ◽  
Anna Vozárová ◽  
Jakub Bazarnik ◽  
Ján Krái
Keyword(s):  
Basaltic Andesite ◽  
Parental Magma ◽  
Crustal Material ◽  
Nd Isotope ◽  
Upper Paleozoic ◽  
Three Samples ◽  
Original Magma ◽  
Basic Rocks ◽  
Nd Isotopic Composition ◽  
Heterogeneous Source

Abstract The paper presents new major and trace element and first Sr-Nd isotope data from selected lavas among the Permian basaltic andesite and basalts of the Hronicum Unit and the dolerite dykes cutting mainly the Pennsylvanian strata. The basic rocks are characterized by small to moderate mg# numbers (30 to 54) and high SiO2 contents (51-57 wt. %). Low values of TiO2 (1.07-1.76 wt. %) span the low-Ti basalts. Ti/Y ratios in the dolerite dykes as well as the basaltic andesite and basalt of the 1st eruption phase are close to the recommended boundary 500 between high-Ti and low-Ti basalts. Ti/Y value from the 2nd eruption phase basalt is higher and inclined to the high-Ti basalts. In spite of this fact, in all studied Hronicum basic rocks Fe2O3* is lower than 12 wt. % and Nb/La ratios (0.3-0.6) are low, which is more characteristic of low-Ti basalts. The basic rocks are characterized by Nb/La ratios (0.56 to 0.33), and negative correlations between Nb/La and SiO2, which point to crustal assimilation and fraction crystallization. The intercept for Sr evolution lines of the 1st intrusive phase basalt is closest to the expected extrusions age (about 290 Ma) with an initial 87Sr/86Sr ratio of about 0.7054. Small differences in calculated values ISr document a partial Sr isotopic heterogeneity source (0.70435-0.70566), or possible contamination of the original magma by crustal material. For Nd analyses of the three samples, the calculated values εCHUR (285 Ma) are positive (from 1.75 to 3.97) for all samples with only subtle variation. Chemical and isotopic data permit us to assume that the parental magma for the Hronicum basic rocks was generated from an enriched heterogeneous source in the subcontinental lithospheric mantle.

scholarly journals REE-bearing minerals in the Rapakavi Grante, Southern Finland

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Thair Al-Ani
Keyword(s):  
Solid Solution ◽  
Electron Probe ◽  
Granitic Magma ◽  
Accessory Mineral ◽  
Hydrothermal Solutions ◽  
Rapakivi Granite ◽  
Solid Solution Series ◽  
Ree Mineralization ◽  
Geochemical Studies ◽  
Primary Minerals

AbstractThe studied rock samples belong to the classic 1615–1645 Ma Wiborg Rapakivi granite terrane of southeastern Finland. Geochemical studies show that the rapakivi granites and associated rocks form metaluminous to peraluminous A-type granites and plot in the "within plate granites (WPG)" field on the tectonic discriminate diagrams from the Onkamaa, Suomenniemi and Luumäki. The rapakivi granite displays enrichment of light over heavy REE (LREE/HREE = 2-34) and usually negative Eu anomalies (Eu/Eu* = 0.01 - 1.4). Enrichment in REE in some studied samples is confined to highly fractionated portions of the Rapakivi granite. Fractional crystallization of the evolving fluorite-rich peraluminous granitic magma was accompanied, particularly at later stages by fluid fractionation, which plays an important role in the genesis of the REE-mineralization. The studied rapakivi granites host REE-minerals including monazite-(Ce), allanite (Ce), bastnäsite (Ce), xenotime, thorite and REE-bearing mineral apatite. Monazite and allanite are the most important REE carriers in the studied granites and these minerals are strongly enriched in the LREE.Monazites are hosted in apatite, quartz, plagioclase, K-feldspar, and biotite. Grain size of monazite is variable ranging from 50 to >100 μm.Monazite contains 48-68 wt% REE2O3, 24.3-29.3 wt% P2O5 and low Th<1.5 wt%ThO2. The Y, REE, U, Th-bearing minerals are not commonly associated with the primary minerals except for Th-bearing minerals, which occur as silicates (e.g. thorite, ThSiO4); and/or replace other elements in the structure of some accessory mineral, especially xenotime, brabantite, zircon, and apatite. Electron probe microanalysis (EPMA) provides an indication of solid solution series between thorite-xenotimezircon, which are related to hydrothermal solutions enriched in REE, Y, P, U, F, and Zr.

scholarly journals Geology, Geochronology and Geochemistry of Weilasituo Sn-Polymetallic Deposit in Inner Mongolia, China

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 104 ◽  
Author(s):  
Fan Yang ◽  
Jinggui Sun ◽  
Yan Wang ◽  
Junyu Fu ◽  
Fuchao Na ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Lower Crust ◽  
Structural Evolution ◽  
Magma Source ◽  
Crustal Material ◽  
Quartz Porphyry ◽  
Polymetallic Deposit ◽  
High Concentrations ◽  
Great Xing’An Range ◽  
Lower Crustal

The recently discovered Weilasituo Sn-polymetallic deposit in the Great Xing’an Range is an ultralarge porphyry-type deposit. The mineralization is closely associated with an Early Cretaceous quartz porphyry. Analysis of quartz porphyry samples, including zircon U-Pb dating and Hf isotopies, geochemical and molybdenite Re-Os isotopic testing, reveals a zircon U-Pb age of 138.6 ± 1.1 Ma and a molybdenite Re-Os isotopic age of 135 ± 7 Ma, suggesting the concurrence of the petrogenetic and metallogenic processes. The quartz porphyry has high concentrations of SiO2 (71.57 wt %–78.60 wt %), Al2O3 (12.69 wt %–16.32 wt %), and K2O + Na2O (8.85 wt %–10.44 wt %) and A/CNK ratios from 0.94–1.21, is mainly peraluminous, high-K calc-alkaline I-type granite and is relatively rich in LILEs (large ion lithophile elements, e.g., Th, Rb, U and K) and HFSEs (high field strength elements, e.g., Hf and Zr) and relatively poor in Sr, Ba, P, Ti and Nb. The zircon εHf(t) values range from 1.90 to 6.90, indicating that the magma source materials were mainly derived from the juvenile lower crust and experienced mixing with mantle materials. Given the regional structural evolution history, we conclude that the ore-forming magma originated from lower crust that had thickened and delaminated is the result of the subduction of the Paleo–Pacific Ocean. Following delamination, the lower crustal material entered the underlying mantle, where it was partially melted and reacted with mantle during ascent. The deposit formed at a time of transition from post-orogenic compression to extension following the subduction of the Paleo–Pacific Ocean.

Some aspects of Tertiary acid magmatism in NE Ireland

1984 ◽  
Vol 48 (348) ◽  
pp. 351-363 ◽  
Author(s):  
I. G. Meighan ◽  
D. Gibson ◽  
D. N. Hood
Keyword(s):  
Northern Ireland ◽  
Central Complex ◽  
Geochemical Data ◽  
Igneous Province ◽  
Granitic Intrusions ◽  
Isotope Evidence ◽  
County Antrim ◽  
Geochemical Studies ◽  
Basic Rocks ◽  
Highly Evolved

Abstract Geochemical data (including REE determinations) are presented for all five Mourne Mountains granites and three Northern Ireland rhyolites. These confirm (1) the extremely fractionated nature of some of the rocks (Sr and Ba &lt; 10 ppm, Rb &gt; 400 ppm, Eu/Eu* &lt; 0.1, and K/Rb &lt; 100), and (2) a major revision to the outcrops of the E. Mourne granites G1 and G2 in which much of the former is reclassified as G2. Combined petrographic and geochemical studies have also indicated that magmatic pulses were involved in the emplacement of Mourne intrusions G2 (Revised)-G5 inclusive. The N. Ireland Tertiary acid rocks exhibit general geochemical similarities to their analogues elsewhere in the British Tertiary Igneous Province (in which Sr is generally &lt; 100 ppm and CeN/YbN generally &lt; 8 with Eu/Eu* often &lt; 0.6), but as a suite the Mourne granites are enriched in Rb and some other LIL elements relative to their N. Arran counterparts. The more fractionated acid magmas of NE Ireland are believed to have evolved from primitive granitic parent liquids by crystal fractionation at depth which involved major and accessory phases (including zircon and allanite). In the Mourne (and County Antrim) areas the primitive acid compositions lie at the ends of basaltic (tholeiitic) differentiation series, and in the Mourne central complex there is a complete geochemical sequence from basic rocks through intermediate members to primitive and ultimately highly evolved, subalkaline, granitic intrusions. It is concluded that the data are consistent with the Mourne granites and Northern Ireland rhyolites being essentially basaltic differentiates, although Sr isotope evidence indicates some (probably minor) crustal involvement.

Granite petrogenesis in the Gander Zone, NE Newfoundland: mixing of melts from multiple sources and the role of lithospheric delamination

2000 ◽  
Vol 37 (4) ◽  
pp. 535-547 ◽  
Author(s):  
David I Schofield ◽  
Richard S D'Lemos
Keyword(s):  
Magma Mixing ◽  
Mobile Belt ◽  
Multiple Sources ◽  
Potential Source ◽  
Iapetus Ocean ◽  
Granite Magmatism ◽  
Host Rocks ◽  
Binary Mixing ◽  
Lower Crustal

Silurian to Devonian granites within the Gander Zone of the Appalachian Central Mobile Belt in northeastern Newfoundland formed adjacent to the former Gondwanan continental margin following terminal closure of the Iapetus Ocean. Comparison of geochemical and isotopic characteristics of the granites with their host migmatites and metasediments, amphibolite, and orthogneiss constrain their potential source. Nd and Sr isotopic compositions indicate that no single source or binary mixing product could have produced the granites. Instead, we show that they result from multicomponent mixing involving a contribution from unexposed crystalline basement, mantle or underplate, and variable contamination by supracrustal host rocks. The timing and composition of granite magmatism do not exhibit collisional orogenic, subduction-related, or continental rifting characteristics. Hence, we relate magmatism to lithospheric melting following delamination of an orogenic keel. This process provides the influx of mantle-derived magma into fertile crust and hence promotes lower crustal melting and primary magma mixing.

scholarly journals Geochemistry of trace elements in rock-forming minerals of gneisses and granites of the Murzinka granite area, Central Urals

2020 ◽  
pp. 74-88
Author(s):  
S.V. Pribavkin ◽  
N.S. Borodina ◽  
M.V. Chervyakovskaya
Keyword(s):  
Trace Elements ◽  
Trace Element Composition ◽  
Element Composition ◽  
Metamorphic Complex ◽  
Granite Pluton ◽  
Formation Conditions ◽  
Granite Magmatism ◽  
Central Urals ◽  
Distribution Of Trace Elements

The Murzinka granite area (Central Urals), which combines Murzinka granite pluton and underlying rocks of the Murzinka-Adui metamorphic complex, exhibits an evident wetrending geochemical zonation of magmatism with increasing of Rb, Li, Nb and Ta contents and decreasing ba and Sr contents and K/Rb, zr/Hf and Nb/Ta ratios from vein granites of the Yuzhakovo complex to granites of the Vatikha complex and further to granites of the Murzinka complex (Fershtater et al., 2019). To develop the ideas about geochemical zonation of the Murzinka granite magmatism, as well as about the role of gneisses of the Murzinka-Adui metamorphic complex in the formation of granites, we studied the distribution of trace elements in biotite and feldspars of gneisses and granites. Biotite shows an increase in Li, Rb, Cs, Nb, Ga, zn, Mn, Sc, Sn and Tl contents and a decrease in V, Cr, Co, Ni, Y, zr and ba contents from vein biotites of the Yuzhakovo granites to two-mica granites of the Murzinka complex. The composition of feldspars also changes in this direction: plagioclase is enriched in Li, Rb, Cs, be, zn and depleted in Sr, ba, Ga and Pb and K-feldspar is enriched in Rb and depleted in Sr and ba. The varying trace element composition of rock-forming minerals of gneisses and granites is explained by We-trending change in the composition of a crustal protolith, as well as the formation conditions of granites. Figures 6. Tables 4. References 17.

Boron and lithium in high-grade rocks and minerals from the Wawa–Kapuskasing region, Ontario

1988 ◽  
Vol 25 (9) ◽  
pp. 1485-1502 ◽  
Author(s):  
D. M. Shaw ◽  
M. G. Truscott ◽  
E. A. Gray ◽  
T. A. Middleton
Keyword(s):  
Fluid Transport ◽  
Fluid Phase ◽  
Distribution Patterns ◽  
Low Grade ◽  
Crustal Material ◽  
High Grade ◽  
Crustal Rocks ◽  
Mineral Equilibria ◽  
Rock Types ◽  
Lower Crustal

There is no preferential partitioning of boron among the principal rock-forming minerals in high-grade rocks of the Kapuskasing Structural Zone (KSZ) and the Wawa Domal Gneiss region (WDG). Lithium is strongly concentrated in biotite and other ferromagnesian minerals but does not show consistent partitioning between these and the sialic minerals.The distribution of B and Li within a rock may be studied using an alpha-track image, which shows that the inconsistencies in partitioning may be largely attributed to disturbance of mineral equilibria by postmetamorphic low-grade alteration that deposited B and Li.Boron has similar concentrations in all the rock types studied, although it is an incompatible element that elsewhere accumulates in pegmatites. Lithium concentrations are low in the anorthositic rocks but are otherwise very variable. In some but not all rocks higher than usual B and Li can be attributed to introduction during alteration.Boron occurs at low concentrations (2–3 ppm) throughout both the KSZ and the WDG areas and has an abundance similar to that in other granulite terranes. It is significantly lower than in average upper crustal rocks (9–15 ppm), and this is attributed to loss by fluid transport during formation of lower crustal material. Lithium occurs at similar concentrations in upper crustal rocks (20–22 ppm) as in the WDG area (27 ppm) but is lower in the KSZ (13 ppm), suggesting again a loss by fluid transport in the deep crust. Both estimates of loss are minima because of the evidence of reintroduction of the elements during later alteration.Although there is field and petrological evidence of anatectic melting in the KSZ–WDG region the distribution patterns of B and Li show no evidence of this: this is not unexpected for elements that readily partition into a fluid phase.

Neoproterozoic evolution of Western Ethiopia: igneous geochemistry, isotope systematics and U–Pb ages

2003 ◽  
Vol 140 (4) ◽  
pp. 373-395 ◽  
Author(s):  
T. GRENNE ◽  
R. B. PEDERSEN ◽  
T. BJERKGÅRD ◽  
A. BRAATHEN ◽  
M. G. SELASSIE ◽  
...  
Keyword(s):  
Trace Elements ◽  
Crustal Material ◽  
East African ◽  
Plate Convergence ◽  
High K ◽  
East African Orogen ◽  
Incompatible Trace Elements ◽  
Back Arc ◽  
Lower Crustal ◽  
Western Ethiopia

New geochemical, isotopic and age data from igneous rocks complement earlier models of a long-lived and complex accretionary history for East African Orogen lithologies north of the Blue Nile in western Ethiopia, but throw doubt on the paradigm that ultramafic complexes of the region represent ophiolites and suture zones. Early magmatism is represented by a metavolcanic sequence dominated by pyroclastic deposits of predominantly basaltic andesite composition, which give a Rb–Sr whole-rock errorchron of 873±82 Ma. Steep REE patterns and strong enrichments of highly incompatible trace elements are similar to Andean-type, high-K to medium-K calc-alkaline rocks; εNd values between 4.0 and 6.8 reflect a young, thin continental edge. Interlayered basaltic flows are transitional to MORB and compare with mafic rocks formed in extensional, back-arc or inter-arc regimes. The data point to the significance of continental margin magmatism already at the earliest stages of plate convergence, in contrast with previous models for the East African Orogen. The metavolcanites overlap compositionally with the Kilaj intrusive complex dated at 866±20 Ma (U–Pb zircon) and a related suite of dykes that intrude thick carbonate-psammite sequences of supposedly pre-arc, continental shelf origin. Ultramafic complexes are akin to the Kilaj intrusion and the sediment-hosted dykes, and probably represent solitary intrusions formed in response to arc extension. Synkinematic composite plutons give crystallization ages of 699±2 Ma (Duksi, U–Pb zircon) and 651±5 Ma (Dogi, U–Pb titanite) and testify to a prolonged period of major (D1) contractional deformation during continental collision and closure of the ‘Mozambique Ocean’. The plutons are characterized by moderately peraluminous granodiorites and granites with εNd values of 1.0–2.0. They were coeval with shoshonitic, latitic, trachytic and rare trachybasaltic intrusions with very strong enrichments of highly incompatible trace elements and εNd of 0.4–8.0. The mafic end-member is ascribed to partial melting of enriched sub-continental mantle that carried a subduction component inherited from pre-collision subduction. Contemporaneous granodiorite and granite formation was related to crustal underplating of the mafic magmas and consequent melting of lower crustal material derived from the previously accreted, juvenile arc terranes of the East African Orogen.

scholarly journals Petrology of the Doda Granites, Jammu Lesser Himalaya, India

1996 ◽  
Vol 14 ◽  
Author(s):  
B. L. Dhar ◽  
A. K. Raina ◽  
B. K. Fotedar ◽  
R. Singh
Keyword(s):  
Partial Melting ◽  
Granitic Rocks ◽  
Crustal Material ◽  
Lesser Himalaya ◽  
Calc Alkaline ◽  
Nw Himalaya ◽  
Jammu And Kashmir ◽  
Lower Crustal ◽  
Highly Evolved

Granitic rocks in the Doda district of Jammu and Kashmir State, NW Himalaya are exposed at eight places. They are named as Dramman, Piparan, Kaplas, Khol Dedni, Chinta, Bhala, Kai Nala, and Nagin Dhar Granites. They occur in the form of irregular bodies of varying dimensions. These granites are mostly leucocratic, two-mica, porphyritic to aplitic, massive and highly jointed with crude foliation in some cases. The contact with the Older Metamorphics is sharp and thermal aureole is absent. These granites are monzo- to syeno-granitic in composition with peraluminous, S-type (equivalent to ilmenite series) and calc-alkaline affinity. These intrusive bodies are emplaced within the Older Metamorphics under tectonic influences at later stages of metamorphism. They have formed from highly evolved anatectic granites derived by partial melting of lower crustal material with diapiric situations. These processes had been operative at a temperature of 600-700°C at a depth of 20-30 km under 5 Kb Pressure. The emplacement of these granites is suggested to be due to transient dilation where the diapir is enhanced by sheeting mechanism.

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