CC BY
11
УДК 552.321(470.5) http://doi.org/10.21440/2307-2091-2022-1-13-21
Geochemical features of the devonian plutonic rocks of the Reftinsky massif (Middle Urals)
Dmitriy Dmitrievich KOROVIN
The Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of RAS, Ekaterinburg, Russia Abstract
This article examines the Devonian plutonic rocks of two massifs - Khomutinsky and Yuzhno-Khomutinsky, which are located in the western part of the Reftinsky massif. The rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs are divided into gabbroid and granitoid associations. Their chemical composition, the content of pertrogenic, rare and trace elements were studied. Based on the data obtained, the rocks were assigned to the calc-alkaline series, according to the ratio of sodium and potassium, they are rocks with a sodium type of alkalinity. The peculiarity of the studied formations lies in the differences in the nature of alkalinity, thus the rocks of the gabbroid association in terms of the K2O content are transitional from low to moderate potassium varieties, and the rocks of the granitoid association are characterized by a sufficiently high potassium content and correspond to the high potassium calc-alkaline series. Comparative analysis with basalts and granites of island arcs allows us to conclude that the Khomutinsky and Yuzhno-Khomutinsky massifs were formed in an island arc geodynamic setting.
Relevance. The geochemical features of the rocks of the Devonian intrusions in the Eastern zone of the Middle Urals have been studied very poorly to date, which makes it difficult to restore the geodynamic conditions of their formation and compare the processes of magmatism in the East of the Middle Urals with other regions of the mobile belt. The data presented in the work will make it possible to fill the existing gap to some extent and thereby help to clarify the patterns of magmatism evolution and the history of the formation of the Urals.
The purpose of the work. Study of the contents of petrogenic, rare and trace elements of the Khomutinsky and Yuzhno-Khomutinsky massifs. Comparison of the geochemical features of the rocks of these intrusions with similar formations formed in island-arc geodynamic conditions.
Research methodology. The chemical composition of rocks was studied by the X-ray fluorescence method, which was performed on a multichannel spectrometer SRM-35 with the determination of losses on ignition by the gravimetric method and the determination of the content of ferrous iron by the titrimetric method. Analysis of the content of rare and trace elements in rocks was carried out on inductively coupled plasma mass spectrometers ELAN 9000 and NexION 300S. Analytical data are presented in the form of discrimination diagrams.
Results. The rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs are divided into gabbroid and granitoid associations. Based on the obtained geochemical data, the rocks were assigned to the calc-alkaline series. According to the ratio of sodium and potassium, they are rocks with a sodium type of alkalinity. It is shown that the rocks of the gabbroid and granitoid associations differ in the character of alkalinity. The former in terms of K2O content are transitional from low to moderate potassium varieties, the latter are characterized by a fairly high content of potassium and correspond to the high potassium calc-alkaline series.
Conclusion. Comparison of the studied rocks in terms of geochemical features with basalts and granites of island arcs allows us to conclude that the Khomutinsky and Yuzhno-Khomutinsky massifs were formed in an island-arc geodynamic setting.
Keywords: granitoids, gabbroids, petrochemistry, geochemistry, Khomutinsky massif, Yuzhno-Khomutinsky massif, Middle Urals.
Introduction
The Reftinsky gabbro-granitoid massif, which is one of the largest areas of magmatism of this type in the Urals, is located within the eastern margin of the Middle Ural segment of the mobile belt. The massif is dominated by gabbro, diorite, and plagioclase granitoids of the Reftinsky complex, along with which there are also a lot of dolerites of a complex of parallel dikes and layered gabbro-ophiolite associations [1]. In the western part of the massif, quartz diorites and tonalites of the Reftinsky complex are broken through by small-sized plutons composed of potassium-sodium granitoids, some bodies also contain rocks of basic and intermediate composition [2]. Information on the composition, age, and conditions of forma-
tion of the rocks that compose these bodies is still extremely limited, which complicates the restoration of the history of the geological development of the region. In this work, for the first time, a sufficiently detailed characteristic of the geochemical features of the rocks of two such bodies, the Khomutinsky and Yuzhno-Khomutinsky massifs, is given, and on the basis of the data obtained, the restoration of the geodynamic conditions of the formation of rocks was carried out.
Geological structure of the district
The Reftinsky massif stretches in the submeridional direction for 60-65 km. Its width reaches 30 km in the southern part and gradually decreases to 15 km in the northern part.
The predominant part of the massif is composed of gabbro, diorite, and plagioclase granitoids of the Reftinsky complex, containing large blocks of iphiolite association rocks. (Comparatively small in size (up to 5 km in diameter) bodies of granitoid, less often gabbro-granitoid composition, breaking through tonalites and quartz diorites of the Reftinsky complex, stretch in the form of a strip of the sfbmeridional direction alonf the western edge of the massif. The Early Silurian age of the rocks of the Reftinsky complex is substantiated by a set is isotope data [3]. Reliable information about the time of intrusio n ofbo dies that break through the rocks of the Reftinsky complex has not yet been obtained. The work of G. B. Ferstater et al. [4] indicate the presence of a dating of 405 ± 8 Ma, obtained by the 207Pb/206Pb method (Kober method, University of Granada, Spain) from zircon from granosdiorite of one of these bodies (Yuzhno-Khomutinsky massif), although the results of the dating are not given. In the explanatory note to the geological map at a scale of 1 : 200 000 of the latest revision [5], there is a link to the earlier obtained Early Carboniferous K-Ar dating from bulk samples of plagiogranitoids of the Ref insky complex from the exocontact zone of the Khomutsinsky massif. According to the authors, the ages obtained are th e result of the influence of the Khomutinsky intrusion. In accordance with these data, some of these bodies are attributed to the Early Carboniferous Nekra-sov gabbro-diorite-granite complex, and the other part to the Early-Middle Devonian Altynai diorite-plagiogranite complex. It should be noted, however, that the data on the Carboniferous age are extremely inconclusive. It is more likely that all intrusions of the considered strip are of the same Devonian age.
The Khomutinsky and Yuzhno-Khomutinsky massifs considered in this work are confined to the southern part of the Reftinsky massif (fig. 1). The shape of the bodies is complex, the total area of the outcrops is more than 40 km2. On the periphery of the massifs, apophyses and small bodies are noted, which join at a depth, forming a single body up to 10 km wide. According to geophysical data, the top wall of the bodies has a low dip, with the exception of the eastern contact, the dip angle of which is steep (70°-80°) up to a depth of 4 km. The Khomutinsky massif contains gabbronorites, gabbros, diorites, quartz diorites, granodiorites, granites and leucogranites. The Yuzhno-Khomutinsky massif is composed of granodiorites.
There are two associations of rocks that have common structural and textural features. The first (gabbroid) includes gabbronorites, gabbro, diorites, quartz diorites; the second (granitoid) is represented by granodiorites, granites and leu-cogranites. The rocks of the gabbroid association are characterized by a medium-grained hypidiomorphic-grained structure; in gabbronorites and gabbros, there are areas with gabb-rodoleritic and dolerite structures. According to the grain size, granodiorites, granites, leucogranites vary from fine to medium-grained, the microstructure is hypidiomorphic-grained. Porphyry varieties are widespread. Classical granite structures have not been observed anywhere, allrockshave signs of weak transformations, consisting; ln partialcataclas eand greenstone alterations. The magmatic process endeS with tCe formation of aplite and pegmatite dikes. On the modern erosional section, the rocks of the gabbroid association make up about half of the area of outcrops. With depth, according to gravimetric data, their number decreases and at a depth of 1.5 km the body is entirely composed of granitoids [6].
Research methodology
The arOicle presenis the results of Sheanalysis of samples from petrographic varieties, most typical for the massifs under consideration. The analyzes were carried out at the Geoanalyst Center forCollective Use at tht IGG UB RAS. X-ray flurre sconce (typisal silicate) analysis of rocks for the content f fbisic elements (Nisi, Mg, Al, Si, P, Sf K, Ca,Ti, Cr, V, Mn, Fe total) was performed on the multichannel spectrometer SRM-35 with determination oflofsos when calcined by the gravimetric method and determination of the contfnt of ferrsus iron by the titrimetric method.
Analysis of the content of rare and trace elements (14 REE and 26 elements Li, Be, Sc, Ti, Cr, Ni, V, Co, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Sb, Cs, Ba, Hf, Ta, Pb, Th, U) in rocks was
61430'
Figure 1. scheme of the geological structure of the southern part of the Reftinsky massif (compiled on the basis of the state geological map [5] with corrections by the author): 1 - Beloyarsk complex: metabasalts and quartz carbonaceous shales (O3bj); 2 - sedimentary rocks of the Cenozoic age; 3 - Alapaevskiy dunite-harzburgite-gabbro complex (Val); Reftinsky complex: 4 - gabbro (vS1); 5 - diorites (5S2); 6 - plagiogranites (pyS2); Devonian intrusions: 7 - gabbro (vDl); 8 -diorites (6D1); 9 - granodiorites (ySD2); 10 - granitoids (yD2);/-Khomutinskymassif; //-Yuzhno-Khomutinsky massif рисунок 1. схема геологического строения южной части Рефтинскоао оассива(сеставлена на осаове иосодарстхенной геолоаическойкарты[0]си сп расоениимиавтора): 1-белояоский ломпиект: тетайазау ьты и кварцевые углистые сланцы (O3bj); 2 - осадочные породы кайнозойского возраста; 3 - алапаевский дунит-гарцбургит-габбровый комплекс (Val); рефтинский комплекс: 4 - габбро (vS1); 5 - диориты (6S2); 6 - плагиограниты (pyS2); девонские интрузии: 7 - габбро (vDl); 8 - диориты (5D1); 9 -гранодиориты (y5D2); 10 - гранитоиды (yD2); / - Хомутинский массив; // - Южно-Хомутинский массив
carried out using the ELAN 9000 and NexION 300S inductively coupled plasma mass spectrometers. The obtained analytical data were processed and presented in the article in the form of various discrimination diagrams.
Geochemical characteristics of the rocks of the devonian intrusions
The chemical composition of the rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs is shown in table 1. The rocks of the gabbroid association of the studied massifs have normal alkalinity (Na2O + K2O in gabbronorite is 2.47 wt. %, in gabbro 2.88-3.33 wt. %, in diorites 3.92-4.05 wt. %, in quartz diorites 5.34-5.50 wt. %). In terms of alkali content, granitoids vary from rocks of normal alkalinity to moderately alkaline (in granodiorites 6.38-6.81 wt. %, in granites 7.31-9.39 wt. %), see
fig. 2, a. On the AFM diagram, the rocks of both associations form a trend located in the field of the calc-alkaline series (fig. 2, b). In terms of Na2O/K2O (15-21 in gabbro, 4-9 in diorites, and 1.3-3.3 in granites), the rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs belong to the sodium type of alkalinity [7]. On the diagram [8], the rocks of the gabbroid association fall on the border of the fields of the low-potassium tholeiitic and moderate-potassium calc-alkaline series, and the granitoids go from the field of the moderate-potassium calc-al-kaline series into the field of the high-potassium calc-alkaline series (fig. 3).
In the rocks of the gabbroid association, the total content of rare earth elements increases with an increase in silicic acidity from gabbro (20.63 ppm) and diorites (18.52-22.36 ppm)
Table 1. Chemical composition of rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs, wt. % Таблица 1. Химический состав пород Хомутинского и Южно-Хомутинского массивов, вес. %
Rocks
Oxides 1 2 3 4 5 6 7 8 9 10 11 12
SiO2 48,26 52,76 52,90 53,90 59,96 60,02 62,85 67,10 70,17 74,49 75,82 77,70
Ti02 0,80 0,39 1,18 0,81 0,86 0,88 0,96 0,61 0,44 0,17 0,11 0,12
Al203 18,22 21,95 19,09 19,48 17,98 18,05 15,28 15,38 14,59 14,26 13,65 12,90
Fe203 3,41 2,95 5,66 5,18 2,82 3,35 4,49 4,33 2,27 0,48 0,40 0,75
FeO 3,50 2,50 2,10 2,70 3,20 2,50 2,80 1,00 1,40 0,40 0,40 0,40
MnO 0,11 0,08 0,11 0,09 0,09 0,08 0,12 0,08 0,07 0,03 0,03 0,03
MgO 8,25 4,41 4,65 3,57 2,22 2,45 1,56 0,79 0,54 0,02 0,01 -
CaO 13,55 9,96 9,53 8,83 6,53 6,66 4,03 3,26 2,14 0,74 1,24 1,05
Na20 2,28 3,55 3,40 3,60 4,37 4,35 4,68 5,03 4,98 5,13 4,59 5,43
K20 0,19 0,37 0,37 0,45 1,13 0,99 1,94 1,50 2,33 3,92 3,34 1,47
P205 0,02 0,05 0,03 0,09 0,14 0,15 0,38 0,25 0,18 0,04 0,04 0,04
LOI 1,15 0,90 0,91 1,07 0,52 0,45 0,78 0,60 0,84 0,34 0,34 0,14
Note: hereinafter in table 2: 1 - gabbro; 2-4 - diorites; 5-6 - quartz diorites; 7-8 - granodiorites; 9 - granites; 10-12 - leucogranites.
Figure2. Petrochemistry ofrocks of the Khomutinskyand Yuzhno-Khomutinskymassifs:s-TAS diagram for chemical classificationof plutonicrocks L. N. SCarpunoC[SU b)trikieACMdiaukam accordingtcT. Irwin cnC V.Caragar[1C].7-rzckcoftCe eranitoid association; 2- rocks of the gabbroidassociation. The lineon the AFM diagram separates the tholeiite andcalc-alkalina field
Рисунок 2. Петрохимия пород Хомутинского if Южно-Хомутинского массивов: а - TAS-диаграмма для хтмической классификации плутонических пород Л. Н. Шарпенок[9]; б-тройная диаграмма AKM по Т. Ирвину к В.Барагару [ 10]; 1- породы гранктгидной ассоциации; 2 - породы габброидной ассоциации. Линия на AFM-диаграмме разделяет поле толеитовой и известково-щелочной серии
Table 2. Trace element composition of rocks of the Khomutinsky and Yuzhno-Khomutinsky massifs, ppm Таблица 2. Микроэлементный состав пород Хомутинского и Южно-Хомутинского массивов, г/т
Rocks
Elements 1 2 3 4 5 6 7 8 9 10 11 12
Li 4 4 3 3 5 6 8,0 8,0 8,0 0,8 4,0 2,0
Be 0,37 0,23 0,22 0,27 0,50 0,50 1,20 1,30 1,40 1,10 1,40 0,38
Sc 37 14 25 19 18 17 15,0 14,0 6,0 11,0 5,0 3,4
Ti 6000 2800 8000 5000 6000 6000 6000 4000 2800 1200 600 600
V 140 80 230 270 140 140 60,0 40,0 24,0 5,0 4,0 0,9
Cr 320 25 50 24 40 37 1,4 3,6 2,8 1,8 1,2 1,0
Mn 800 500 800 700 600 600 800 500 500 130 150 130
Co 32 17 25 25 17 17 10,0 6,0 4,0 0,60 0,6 0,3
Ni 80 23 34 26 28 26 3,0 5,0 4,0 1,7 2,1 1,4
Cu 70 9 27 32 33 29 12,8 9,0 9,0 7,0 5,0 6,0
Zn 23 24 50 40 60 50 60 50 50 22 15 19
Ga 10 16 17 18 17 17 20 20 18 18 15 11
Ge 1,2 1,0 1,0 1,0 1,2 1,1 1,3 1,1 1,3 1,5 1,3 1,4
As 0,17 0,48 0,35 0,35 1,50 1,16 0,59 0,29 0,35 0,78 0,22 0,06
Se 0,36 0,17 0,49 0,57 0,62 0,69 1,09 0,77 0,93 0,56 0,34 0,31
Rb 2,4 4,0 7,0 10,0 23,0 19,0 28 14 42 20 35 7
Sr 400 500 800 800 600 600 500 400 400 140 210 180
Y 11 6 12 12 23 23 50 26 40 14 9 7
Zr 40,4 23,0 42,0 38,3 130 120 53 200 170 180 67 56
Nb 2,3 1,6 3,8 3,1 8,0 7,0 18 17 18 19 12 5
Mo 0,16 0,11 0,40 0,40 1,60 1,50 0,80 0,90 3,40 0,70 0,18 0,16
Ag 0,19 0,30 0,04 0,03 0,10 0,09 0,19 0,16 0,18 0,25 0,14 0,05
Cd 0,05 0,05 0,11 0,12 0,13 0,06 0,14 0,12 0,10 0,13 0,05 0,06
Sn 0,50 0,32 0,34 0,46 0,90 0,80 2,0 1,8 2,4 0,9 0,9 0,7
Sb 0,02 0,04 0,03 0,04 0,12 0,09 0,04 0,03 0,04 0,05 0,03 0,02
Te 0,01 0,02 0,01 0,02 0,01 0,01 0,01 0,01 0,01 0,06 0,02 0,01
Cs 0,04 0,11 0,14 0,16 0,45 0,43 0,44 0,46 0,60 0,03 0,23 0,03
Ba 40 90 100 120 210 200 270 280 310 270 300 330
La 2,0 3,0 3,2 4,0 9,0 9,0 11 17 18 7 6 7
Ce 5 6 7 8 19 19 37 33 34 17 12 15
Pr 0,9 0,8 0,8 0,9 2,1 2,1 3,5 3,7 3,7 2,2 1,4 1,9
Nd 4,4 3,5 3,4 3,9 8,0 9,0 14 14 14 9 5 7
Sm 1,3 0,9 0,9 0,9 1,9 2,0 3,4 2,7 2,9 1,8 1,1 1,5
Eu 0,60 0,45 0,47 0,46 0,60 0,60 1,00 0,80 0,70 0,30 0,37 0,26
Gd 1,7 1,1 1,2 1,2 2,4 2,3 4,0 3,0 3,5 2,0 1,1 1,3
Tb 0,27 0,16 0,17 0,17 0,30 0,30 0,60 0,40 0,50 0,30 0,16 0,15
Dy 1,8 1,0 1,1 1,1 2,2 2,1 3,8 2,7 3,3 1,9 1,1 0,9
Ho 0,37 0,22 0,23 0,23 0,50 0,50 0,80 0,60 0,70 0,40 0,22 0,18
Er 1,1 0,6 0,7 0,7 1,4 1,3 2,4 1,7 2,2 1,3 0,7 0,6
Tm 0,15 0,09 0,10 0,10 0,20 0,19 0,35 0,25 0,34 0,20 0,12 0,09
Yb 0,9 0,6 0,6 0,6 1,3 1,3 2,3 1,6 2,2 1,4 0,9 0,7
Lu 0,14 0,10 0,10 0,10 0,20 0,20 0,30 0,25 0,40 0,22 0,14 0,12
Hf 0,80 0,57 0,61 0,62 1,50 1,60 0,8 1,8 2,0 2,3 1,4 1,2
Ta 0,15 0,12 0,13 0,12 0,31 0,33 0,70 0,50 0,80 0,70 0,80 0,16
W 0,04 0,06 0,10 0,09 0,30 0,40 0,09 0,06 0,07 0,10 0,05 0,10
Tl - 0,02 0,02 0,03 0,06 0,08 0,11 0,11 0,16 0,17 0,15 0,06
Pb 0,8 1,7 1,8 2,4 5,0 6,0 7 6 9 9 12 10
Th 0,16 0,50 0,61 0,72 2,10 2,40 2,5 2,7 5,0 3,3 4,8 3,9
U 0,12 0,16 0,27 0,32 0,90 1,10 1,00 0,60 2,10 0,41 1,90 0,49
Eu/Eu* 1,23 1,38 1,38 1,35 0,83 0,88 0,83 0,86 0,67 0,48 1,03 0,57
Lan/Ybn 1,59 3,59 3,83 4,78 4,96 4,96 3,43 7,62 5,87 3,58 4,78 7,17
I REE 20,63 18,52 19,97 22,36 50,20 48,79 84,45 81,70 86,44 45,02 30,31 36,70
Figure 4. Distributionof REE [13] in the rocks of the Khomutinsky andYuzhno-Khomutinsky massifs: s - in the rocks of thegabbroid association ondthe ir comparison with the basaltsofisiaod arcs[ 14]; b - in the roc kcofthe g oanitoid association and thoir compcrison withtho grcmtes oftko iciand arcst12CLegend he^^k^itickf^.lf.it - satbroo ft he Khonrotiosktmacsir; ^^r^ionlesoCthiei Khomatinkty meckif; Ccquaho cJiorit^sso^l^hs Khamu^ik^l<omc^a; ^q granoOioetsoofttie Yuehno-Khomutinskym asu¡f;h-araaedioritooorthe KhomutieuhsmaosifiC -grcmtas ottOe e^^r^mlfr¡nsky
Рисунок 4. Распределение РЗЭ 113] в породах Хомутинского и Южно--омутинского массивоо: а - в породах габброидной ассоlnиацеи и их сравнеуие с базальтами островных дуг [ 14]; б - ej по родах гранитоидн2Й ассоциации и их сравнение с гранитами островных дуг [12]. Условные обозначения здесь и на рис. 5: 1 - габбро Хомутинского массива; 2 - диориты Хомутинского массива; 3- кварцевы-диориты Хомутинского массива; 4- гранодиориты Южно-Хомутинского массива; 5 -гранодио°иты Хомутинскоро массива; 6 - г°аниты Хомутивскогомассива
Figure 3. Diagram K20-Si02 for the separation of igneous rocks by potassium content [8]: 1 - rocks of the granitoid association; 2 - rocks ofthg gabDroid astooiation
Рисунлк 3. Диафамма K20-Si0] одядааделпнип ма-матг-есксу поуод f<sc^^epiK<^-<i^iy калия [8fi ; o порода fpaниaоoыcoh acccaиа^и^-иорода г—п°^|ос^с^пной ассоциации
Rock/Chondtiles 100
Sutn-McDon. 1989-REEs
Ce Nd Sm Gd Dy Er Yb
La Pr Pm Eu Tb Ho Tm Lu
Rock/Chorïdrites 100
Sun+McDon. 1989-REEs
t_I_1_I_i_I_I_I_I_I_L.
Ce Nd Sm Gd Dy Er Yb La Pr Pm Eu Tb Ho Tm Lu
• I 4 5
Ul 6
h
to quartz diorite (48.79-50.20 ppm). The graphs of REE distribution in gabbro and diorites are characterized by the presence of a positive europium anomaly (Eu/Eu* = 1.23 in gabbro and 1.35-1.38 in diorites), in quartz diorites the sign of the europium anomaly is reversed (Eu/Eu* = 0.83-0.88). The value of the lanthanum-ytterbium ratio with an increase in the silicic acidity of the rocks increases from gabbro (1.59), to diorites (3.59-4.78) and quartz diorites (4.96). In terms of the content and distribution of REE, the rocks of the first association are close to the basalts of island arcs (fig. 4, a).
The behavior of rare earths in rocks of the granitoid association has the opposite tendency: with an increase in silica content, the amount of REE decreases from granites, granodiorites (86.44-81.70 ppm) to leucogranites (45.02-30.31 ppm). A negative Eu anomaly is observed on the graphs of REE distribution in both granodiorites and granites. The Eu/Eu* value varies from 0.83 to 0.86 in granodiorites, 0.67 in granite, and from 0.48 to 1.03 in leucogranites (fig.4, h). Light elements of the spectrum
prevail over heavy ones: the value of the lanthanum-ytterbium ratio varies from 3.43 to 7.62 in granodiorites, 5.87 in granite and from 3.58 to 7.17 in leucogranites (table 2). In terms of the REE content, the rocks of the granitoid association are close to the granites of the island arcs (IAG), differing from them by the presence of a negative Eu anomaly; in the rocks of the gabbroid association, a positive europium anomaly is observed.
Spider diagrams of the distribution of rare and trace litho-philic elements (fig. 5, a) are characterized by the presence of well-pronounced minima of Th, Nb, Ce and maxima of Ba, K, Sr, which is a characteristic feature of island arc basalts (IAB) [11]. Fig. 5 clearly illustrates the uniform nature of the distribution of elements in the studied gabbroids and in the basalts of island arcs, as well as a clearly pronounced pattern consisting in an increase in the concentrations of all lithophilic rare elements with an increase in potassium alkalinity.
The graphs of the distribution of rare and trace litho-philic elements in the granitoids of thedescribed massifsare
Р1диге 5. МрИег Падуатвои Шес^пЬиОопоТ г^^^^г^с! Ссасе МиОорОШс е1етеп-и ¡иН1е гсокп оО Ше ОИеоУшвку апс-УигИпе-К^с^т^^йпвку тааоав: а - ¡п ¡Пегоскэ оНЬееаЬПгойазэпаааОюп потрапэопгмаНе [14];Ь - ¡п (Ре госкэ оГ
кадгапеой аээо^аПюпапс) ((1епп4таег;50п аедеапКепоНПе ¡э1ап( агсэ [1 П1
Рисунок 5. Спайдер-диаграммы [распределения редких и рассеянных, литофильных элементов в породах Хомутинского и Южно-Хомутинского массивов: а - в породах габброидной ассоциации и их сравнение с базальтами островных дуг [ 14]; б - в породах гранитоидной аксоциации и их сравнение с гранитами оатровныых дуа [11]
Figure 6. Diagramsof ueodynamic settings by J. Pearce[15]: a - — eratio ofb b to th e ^u mm Y an dNb; b- t he rat i oofRb tot he sum of Yb aodTe.7 - granitos ettho Khomrifissky massif;2 - granodiorifes of the Yushno-Khomutinsfymassif
Рисунок 6. Диаграммы геодинамических обстановок Дж. Пи рса [15 ]: а - отношение Rb к сумме Y и Nb; б - отношение Rb к сумме Yb и Ta; 1 - граниты Хомутинского массива;2- гранодиориты Южно-Хомутинского массива
also characterized by the presence of a maximum in K and, to a lesser extent, in Sr, as well as a minimum Nb (fig. 5, b). In addition, they have distinct Ta and Ti minima and Zr maximum. In terms of the observe d distribution pattern and the yontent оf most оГ the elements, the studied granitoids are -very close to the izland arc granttes (IAG) described by S. N.Rudnevet al. [12].
On the discrimination diagramt by J. Pearce [14]r most ef the figurative points of granodiorites, granites, leucogranites of the Khomutinsky mass rock and granodiorites of the Yu-zhno-Khomutinsky mass rock - lie in the field of volcamc arc granites (VAG), which is consistent with the above date on the proximity ef the studied rocks in terms of gce chemfcal features to magmatie formations hormed in an island arc setting (fig. e).
ton elusion
The data presented in this work indicate that the intru-
sive Wormations of the Khomutinsky ond Yuzhno-Khomutin-sky massifs belong to the calc-alkaline series. According to the ratio of sodium and potassium, they are rocks with a sodium type of alkalinity.A feature of the studiet. form ations is that the rocks ofbasic and acidic composition diffor significantly in the nature оf alkalintty. The rocks yf the early gabbroid assoeiation oi rocks, including gabbitУoritea) gabbros, diorites and quartz diorites, are typical rocks of normal alkalinity and, tn terms rf K2O content, are transitional from low to moderate potassium varieties. At the same time, the rocks of the later granitoid association (granodiorites, granites and leucogranites), in terms of the total alkali content, vary from rocks oî nyrmaf alkalinity to subalkaline f nes and are characterized by a sufficienrly high potassium content. Aceording to the classification, a significant part of the silicic rocks of the studied massifs corresponds to the high-potassium calc-alkaline series.
On the discrimination diagrams, the rocks of the studied massifs fall into the field of granites of volcanic belts, and in terms of the content of most rare and trace elements, they are
close to the rocks of island arcs similar in silicic acidity, which allows us to conclude that the Khomutinsky and Yuzhno-Khomu-tinsky massifs were formed in an island arc geodynamic setting.
The work was carried out within the framework of the state assignment of the IGG UB RAS (registration no. AAAA-A18-118052590032-6).
REFERENCES
1. Lobova E. V. 2013, Silurian intrusive magmatism of the Eastern zone of the Middle Urals, PhD thesis. St. Petersburg, 20 p. (In Russ.)
2. Smirnov V. N. 1981, Gabbro-granitoid series of the Eastern zone of the Urals. Doklady AN SSSR [Reports of the Academy of Sciences of the USSR], vol. 259, no. 6, pp. 1453-1457. (In Russ.)
3. Smirnov V. N., Nastavko E. V., Ivanov K. S., Bayanova T. B., Rodionov N. V., Serov P. A. 2014, Results of isotopic dating of rocks of the Reftinskiy gabbro-diorite-tonalite complex, Eastern zone of the Middle Urals. Litosfera [Lithosphere], no. 5, pp. 3-18. (In Russ.)
4. Fershtater G. B., Krasnobaev A. A., Bea F., Montero P., Borodina N. S., Kholodnov V. V., Zinkova E. A., Shardakova G. Yu., Pribavkin S. V. 2007, Stages of Paleozoic intrusive magmatism of the Ural orogen and their geodynamic interpretation. Geodynamics, magmatism, metamorphism and ore formation. Collection of scientific papers. Ekaterinburg, pp. 89-120. (In Russ.)
5. Kazakov I. I., Storozhenko E. V., Kharitonov I. N., Stefanovsky V. V., Koshevoy Yu. N., Kozmin S. V., Martynov S. E., Fadeicheva I. F., Ronkin Yu. L., Lukin V. G. 2017, State Geological Map of the Russian Federation, scale 1 : 200 000 (second edition). Series Middle Ural. Sheet O-41-XXVI (Asbest). Explanatory letter. St. Petersburg, 284 p. (In Russ.)
6. Smirnov V. N. 1982, Reftinsk area of intrusive magmatism (East Ural volcanogenic zone). Sverdlovsk, 268 p. (In Russ.)
7. 2008, Petrographic Code of Russia. Magmatic, metamorphic, metasomatic, impact formations. Second edition, revised and enlarged. St. Petersburg, 200 p. (In Russ.)
8. Peccerillo A., Taylor S. R. 1976, Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu Area, Northern Turkey. Contributions to Mineralogy and Petrology, vol. 58, pp. 63-81. https://doi.org/10.1007/BF00384745
9. Sharpenok L. N., Kostin A. E., Kukharenko E. A. 2013, TAS-diagram of the sum of alkalis - silica for chemical classification and diagnostics of plutonic rocks. Regional'naya geologiya i metallogeniya [Regional geology and metallogeny], no. 56, pp. 40-50. (In Russ.)
10. Irvine T. N., Baragar W. R. A. 1971, A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, vol. 8, no. 5, pp. 523-548. https://doi.org/10.1139/e71-055
11. Volynets O. N., Antipin V. S., Perepelov A. B., Anoshin G. N. 1990, Geochemistry of volcanic series of the island-arc system in application to geodynamics (Kamchatka). Geologiya i geofizika [Geology and Geophysics], no. 5, pp. 3-13. (In Russ.)
12. Rudnev S. N., Babin G. A., Kovach V. P., Kiseleva V. Yu., Serov P. A. 2013, The early stages of island-arc plagiogranitoid magmatism in Gornaya Shoriya and West Sayan. Geologiya i geofizika [Geology and Geophysics], vol. 54, no. 1, pp. 27-44. (In Russ.)
13. Sun S. S, McDonough W. F. 1989, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications, vol. 42, no. 1, pp. 313-345. http://dx.doi.org/10.1144/GSL.SP.1989.042.01.19
14. Grib E. N., Leonov V. L., Perepelov A. B. 2009, Geochemistry of volcanic rocks of the Karymsky volcanic center. Vulkanologiya i seysmologiya [Vulkanology and seismology], no. 6, pp. 1-23. (In Russ.)
15. Pearce J. A., Harris N. B. W., Tindle A. G. 1984, Trace element discrimination diagrams for the tectonic interpretation of granitic rock. Journal of Petrology, vol. 25, pp. 956-983. https://doi.org/10.1093/petrology/25A956
The article was received on December 27, 2021
УДК 552.321(470.5) http://doi.org/10.21440/2307-2091-2022-1-13-21
Геохимические особенности девонских плутонических пород Рефтинского массива (Средний Урал)
Дмитрий Дмитриевич КОРОВИН
Институт геологии и геохимии им. акад. А. Н. Заварицкого УрО РАН, Екатеринбург, Россия Аннотация
Актуальность. Геохимические особенности пород девонских интрузий Восточной зоны Среднего Урала до настоящего времени изучены очень слабо, что затрудняет реставрацию геодинамических условий их образования и сопоставление процессов магматизма востока Среднего Урала с другими регионами подвижного пояса. Изложенные в работе данные позволят в какой-то степени заполнить существующий пробел и тем самым будут способствовать уточнению закономерностей эволюции магматизма и истории формирования Урала.
Цель работы. Изучение содержаний петрогенных, редких и рассеянных элементов Хомутинского и Южно-Хомутинского массивов. Сравнение геохимических особенностей пород этих интрузий, с аналогичными образованиями, формировавшимися в островодужных геодинамических условиях.
Методология исследования. Химический состав горных пород изучался рентгенофлюоресцентным методом, который выполнен на многоканальном спектрометре СРМ-35 с определением потерь при прокаливании гравиметрическим методом и определением содержания двухвалентного железа титрометрическим методом. Анализ содержания редких и рассеянных элементов в горных породах проводился на масс-спектрометрах с индуктивно-связанной плазмой ELAN 9000 и NexION 300S. Аналитические данные представлены в виде дискриминационных диаграмм.
Результаты. Породы Хомутинского и Южно-Хомутинского массивов разделены на габброидную и гранитоидную ассоциацию. На основании полученных геохимических данных породы были отнесены к известково-щелочной серии. По соотношению натрия и калия они представляют собой породы с натриевым типом щёлочности. Показано, что породы габброидной и гранитоидной ассоциаций отличаются по характеру щёлочности. Первые по содержанию K2O являются переходными от низко- к умереннокалиевым разновидностям, вторые характеризуется достаточно высоким содержанием калия и соответствует высококалиевой известково-щелочной серии.
Заключение. Сопоставление изученных пород по геохимическим особенностям с базальтами и гранитами островных дуг позволяет сделать вывод о формировании Хомутинского и Южно-Хомутинского массивов в островодужной геодинамической обстановке.
Ключевые слова: гранитоиды, габброиды, петрохимия, геохимия, Хомутинский массив, Южно-Хомутинский массив, Средний Урал.
ЛИТЕРАТУРА
1. Лобова Е. В. Силурийский интрузивный магматизм Восточной зоны Среднего Урала: автореф. дис. ... канд. геол.-минерал наук. СПб: НМСУ «Горный», 2013. 20 с.
2. Смирнов В. Н. Габбро-гранитоидные серии Восточной зоны Урала // Доклады АН СССР. 1981. Т. 259. № 6. С. 1453-1457.
3. Смирнов В. Н., Наставко Е. В., Иванов К. С., Баянова Т. Б., Родионов Н. В., Серов П. А. Результаты изотопного датирования пород Рефтинского габбро-диорит-тоналитового комплекса, Восточная зона Среднего Урала // Литосфера. 2014. № 5. С. 3-18.
4. Ферштатер Г. Б., Краснобаев А. А., Беа Ф., Монтеро П., Бородина Н. С., Холоднов В. В., Зинькова Е. А., Шардакова Г. Ю., Прибавкин С. В. Этапы палеозойского интрузивного магматизма Уральского орогена и их геодинамическая интерпретация // Геодинамика, магматизм, метаморфизм и рудообразование: сб. науч. трудов. Екатеринбург: ИГГ УрО РАН, 2007. С. 89-120.
5. Казаков И. И., Стороженко Е. В., Харитонов И. Н., Стефановский В. В., Кошевой Ю. Н, Козьмин С. В., Мартынов С. Э., Фадеичева И. Ф., Ронкин Ю. Л., Лукин В. Г. Государственная геологическая карта Российской Федерации масштаба 1 : 200 000 (изд. 2-е). Сер. Средне-Уральская. Лист O-41-XXVI (Асбест): объяснит. записка. СПб: ВСЕГЕИ, 2017. 284 с.
6. Смирнов В. Н. Рефтинский ареал интрузивного магматизма (Восточно-Уральская вулканогенная зона). Свердловск, 1982. 268 с.
7. Петрографический кодекс России. Магматические, метаморфические, метасоматические, импактные образования. Изд. 2-е, перераб. и доп. СПб: ВСЕГЕИ, 2008. 200 с.
8. Peccerillo A., Taylor S. R. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu Area, Northern Turkey // Contributions to Mineralogy and Petrology. 1976. Vol. 58. P. 63-81. https://doi.org/10.1007/BF00384745
9. Шарпенок Л. Н., Костин А. Е., Кухаренко Е. А. TAS-диаграмма сумма щелочей - кремнезем для химической классификации и диагностики плутонических пород // Региональная геология и металлогения. 2013. № 56. С. 40-50.
10. Irvine T. N., Baragar W. R. A. A guide to the chemical classification of the common volcanic rocks // Canadian Journal of Earth Sciences. 1971. Vol. 8. No. 5. P. 523-548. https://doi.org/10.1139/e71-055
11. Волынец О. Н., Антипин В. С., Перепелов А. Б., Аношин Г. Н. Геохимия вулканических серий островодужной системы в приложении к геодинамике (Камчатка) // Геология и геофизика. 1990. № 5. С. 3-13.
12. Руднев С. Н., Бабин Г А., Ковач В. П., Киселева В. Ю., Серов П. А. Ранние этапы островодужного плагиогранитоидного магматизма Горной Шории и Западного Саяна // Геология и геофизика. 2013. Т. 54. № 1. С. 27-44.
13. Sun S. S., McDonough W. F. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes // Geological Society, London, Special Publications. 1989. Vol. 42. № 1. Р. 313-345. http://dx.doi.org/10.1144/GSL.SR1989.042.01.19
14. Гриб Е. Н., Леонов В. Л., Перепелов А. Б. Геохимия вулканических пород Карымского вулканического центра // Вулканология и сейсмология. 2009. № 6. С. 1-23.
15. Pearce J. A., Harris N. B. W., Tindle A. G. Trace element discrimination diagrams for the tectonic interpretation of granitic rock // Journal of Petrology. 1984. Vol. 25. P. 956-983. https://doi.org/10.1093/petrology/25A956
Статья поступила в редакцию 27 декабря 2021 года
