On the oxidation coefficient (F) of intrusive rocks of the Upper Kondoma granodiorite massif
Abstract Generated abstract
This paper examines the oxidation coefficient F, defined as the Fe2O3 to FeO ratio, in rocks of the Verkhne-Kondomsky granodiorite massif in Mountain Shoria. Using chemical analyses of fresh intrusive rocks, metasomatic varieties, and dike formations, it compares F across the main granodiorite phase, younger trondhjemites, feldspathized rocks, products of magnesian metasomatism, and several dike types. The study finds that F varies with mineralogical composition and postmagmatic alteration, but also generally decreases from the main intrusive phase to later intrusive and vein formations. It suggests that oxidation coefficients may serve as an auxiliary criterion for establishing the relative sequence of intrusive phases.
Full Text
On the Oxidation Coefficient \((F)\) of Intrusive Rocks of the Verkhne-Kondomsky Granodiorite Massif
B. F. NIFANTOV
(Presented by Prof., Dr. A. M. Kuzmin)
In the present article an attempt is made to examine the behavior of the ratio \(F = \mathrm{Fe}_2\mathrm{O}_3 : \mathrm{FeO}\) in different parts of one of the granodiorite massifs of Mountain Shoria. For this purpose the author calculated the oxidation coefficients \((F)\) both for intrusive rocks unaltered by postmagmatic processes and for metasomatic and dike formations that arose as a result of the postmagmatic activity of the massif under study.
The question of the role of oxygen in the process of formation of magmatic rocks has been studied by many researchers: F. Yu. Levinson-Lessing, A. N. Zavaritsky, N. Bowen, V. M. Goldschmidt, D. S. Korzhinsky, V. V. Shcherbina, A. G. Betekhtin, T. Barth, and others. In recent times petrologists have continued to study the behavior of oxygen and its isotopes [6] in the process of petrogenesis. S. I. Shchukin [5] studied the ratio
\[ \omega = \frac{\mathrm{Fe}^{+3}}{\mathrm{Fe}^{+2} + \mathrm{Fe}^{+3}} \]
in volcanogenic rocks of the Southern Tien Shan and came to the conclusion that the oxidation coefficient \((\omega)\) may be used in the classification of volcanogenic rocks as a basic genetic feature indicating the depth of formation of volcanogenic products.
Yu. S. Kutsev [2] arrived at conclusions close to those of S. I. Shchukin while studying the behavior of the ratio \(F = \mathrm{Fe}_2\mathrm{O}_3 : \mathrm{FeO}\), which he called the oxidation coefficient, in intrusive and effusive rocks of certain regions of the Soviet Union and foreign countries. In Kutsev’s opinion, the principal factor determining the magnitude of the partial pressure of oxygen and the ratio \(\mathrm{Fe}_2\mathrm{O}_3 : \mathrm{FeO}\) in rocks is the depth factor. It is indicated [2] that, in the general case, the value of \(F\) increases in the transition from deep-seated magmatic rocks to sedimentary rocks in the following sequence: deep intrusive rocks → vein rocks → extrusive rocks → pyroclastic rocks → sedimentary (clastic) rocks.
The oxidation coefficient \(F\) does not remain constant, changing over the course of time under the action of various causes. The \(F\) of intrusive rocks may change under the influence of autometasomatic, superimposed hydrothermal, and other processes of postmagmatic activity. On the other hand, in a modern section of an intrusion the value of \(F\) changes depending on the degree of weathering of the rocks. This must be taken into account when selecting samples for chemical analysis and selective-
…ness of weathering. It is known that weathering first of all penetrates intrusive rocks along fractures and along jointing with a blocky pattern. In this process ferrous iron is oxidized to \(\mathrm{Fe_2O_3}\), and the numerical value of the coefficient \(F\) increases. Consequently, when studying \(F\) for an intrusion exposed by erosion, it is necessary to select for analyses only fresh samples not affected by weathering. In addition, the oxidation coefficient depends on the depth of occurrence of the rocks, on the degree of influence of the products of radioactive decay, and on the prolonged action of the sun’s rays on the rocks under investigation.
In the present work an attempt is made to determine the change in the numerical value of \(F\) as a function of the mineralogical and chemical composition of intrusive rocks situated at approximately the same topographic level in the present erosional section.
Below the author gives examples of variation in the oxidation coefficient for fresh intrusive and dike rocks of the Verkhne-Kondomsky massif, belonging to different phases of intrusion, and for intrusive rocks altered by postmagmatic metasomatic processes.
The Verkhne-Kondomsky granodiorite massif is located in the southern part of Gornaya Shoria, in the upper reaches of the Kondoma River and its right tributary, the Taimet River.
Within the intrusion two phases, differing in composition and time of formation, are distinguished: the main granodiorite phase and the younger trondhjemite phase, which cuts the intrusive rocks of the main phase [4]. In addition, areas of metasomatically altered rocks have been distinguished, among which potassic varieties are recognized, outwardly similar to syenites, and intrusive rocks altered by processes of magnesian metasomatism. The latter are metasomatic gabbro-diorites and giant-grained hornblendites, which occur as separate areas in the roof and endocontacts of the Verkhne-Kondomsky granodiorite massif.
Oxidation coefficient of the intrusive rocks of the main phase of intrusion
The intrusive rocks of the main phase of intrusion are represented by granodiorites, quartz diorites, and diorites, very close to one another in their chemical composition, differing only in certain textural features and in the content of free silica. The most widespread in the field of the massif are quartz diorites—macroscopically medium- and coarse-grained rocks, slightly porphyritic owing to the presence in their general mass of large, 0.5–1 cm, segregations of plagioclase, quartz, or dark-colored minerals. At the same time, the average sizes of the rock-forming mineral grains composing the rock for the most part range within 0.2–0.4 cm.
Under the microscope, the rocks of the main phase consist of oligoclase no. 21–23 (44–72%), quartz (18–42%), orthoclase (0.5–5%), hornblende (3–11%), and biotite (1–7%). Accessory minerals are magnetite, apatite, sphene, and zircon. The mineralogical composition of the intrusive rocks is illustrated in Table 1.
The rocks of the main intrusive phase are characterized by substantial variability, at individual points of the massif, in the contents of plagioclase, quartz, and common hornblende.
In chemical features the quartz diorites and diorites of the main phase are distinguished by an uneven content in the analyses of silica (46–69%), magnesium oxide (0.3–6.8%), calcium oxide (2.7–10.3%),
which is due to the uneven distribution, within the massif, of rock-forming minerals.
The values of $F$ vary from 0,49 to 1,10, averaging 0,75. $F$ does not depend on the absolute amount of dark-colored minerals in the rock, but reflects fluctuations in the amounts of ferric and ferrous iron oxides in their composition (Tables 2, 3).
Table 1
Mineralogical composition of rocks of the main intrusive phase of the Verkhne-Kondomsky granodiorite massif (in volume percent)
| No. | Sample numbers | Plagioclase | Plagioclase number | Quartz | Orthoclase | Hornblende | Biotite | Magnetite | Sphene | Apatite | Sum |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2022 | 68,0 | 22 | 17,7 | 4,6 | 4,2 | — | 2,5 | 1,5 | 1,5 | 100 |
| 2 | 2159 | 67,7 | 22 | 22,7 | 0,3 | 4,5 | 2,5 | 1,5 | — | 0,8 | 100 |
| 3 | 2156 | 71,9 | 22 | 20,1 | 3,3 | 2,8 | 1,1 | 0,8 | — | — | 100 |
| 4 | 2154/2 | 70,3 | 22 | 19,7 | 1,7 | — | 6,6 | 1,7 | — | — | 100 |
| 5 | 2153/3 | 44,5 | 22 | 42,3 | — | 11,9 | — | — | 1,3 | — | 100 |
| Average | 67,0 | 22 | 22 | 2,0 | 4,7 | 2,0 | 1,3 | 0,5 | 0,5 |
Table 2
Chemical composition of rocks of the main intrusive phase of the Verkhne-Kondomsky granodiorite massif (in weight percent)
| No. | Sample numbers | SiO₂ | TiO₂ | Al₂O₃ | Fe₂O₃ | FeO | MnO | MgO | CaO | Na₂O | K₂O | l.o.i. | $F$ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2244/3 | 66,77 | 0,44 | 16,88 | 1,56 | 2,61 | 0,09 | 0,27 | 2,70 | 4,93 | 2,57 | 0,74 | 0,60 |
| 2 | 2263 | 69,26 | 0,35 | 16,12 | 1,25 | 2,25 | 0,07 | 0,66 | 2,37 | 4,95 | 2,50 | 0,41 | 0,56 |
| 3 | 96 | 68,43 | 0,36 | 15,98 | 1,83 | 1,66 | 0,08 | 0,80 | 3,12 | 4,42 | 2,52 | 0,35 | 1,10 |
| 4 | 2244 | 65,02 | 0,53 | 16,59 | 2,02 | 2,75 | 0,08 | 1,27 | 3,59 | 5,00 | 2,33 | 0,73 | 0,74 |
| 5 | 26 | 67,03 | 0,40 | 19,58 | 1,96 | 2,08 | 0,07 | 1,31 | 3,03 | 4,71 | 1,74 | 0,57 | 0,94 |
| 6 | 2243 | 65,69 | 0,49 | 16,22 | 2,05 | 2,64 | 0,06 | 1,33 | 3,69 | 4,91 | 2,08 | 0,45 | 0,78 |
| 7 | 2023 | 64,40 | 0,44 | 17,15 | 1,57 | 2,54 | — | 1,38 | 3,46 | 5,08 | 2,39 | 1,55 | 0,62 |
| 8 | 2173 | 57,98 | 0,83 | 18,75 | 2,86 | 3,94 | 0,12 | 2,25 | 5,52 | 4,53 | 1,83 | 0,50 | 0,72 |
| 9 | 46 | 59,05 | 0,86 | 18,69 | 2,12 | 4,10 | 0,15 | 2,46 | 2,91 | 5,06 | 2,34 | 1,62 | 0,52 |
| 10 | 48 | 58,37 | 0,79 | 17,11 | 3,31 | 3,48 | 0,06 | 3,30 | 5,40 | 4,03 | 2,32 | 0,88 | 0,95 |
| 11 | 2281 | 58,26 | 0,97 | 16,58 | 2,25 | 4,18 | 0,08 | 3,34 | 5,72 | 4,80 | 2,50 | 0,45 | 0,49 |
| 12 | 54 | 46,03 | 1,58 | 17,33 | 5,22 | 5,59 | 0,05 | 6,81 | 10,34 | 3,20 | 0,83 | 0,56 | 0,94 |
| Average value | 0,75 |
Chemical analyses of rocks of the Verkhne-Kondomsky massif, presented here and below, were performed by the chemical laboratory of ZSTU.
Table 3
Values of \(F\) for hornblendes from various regions of the USSR
| No. | List no. | Mineral | Weight percent Fe₂O₃ | Weight percent FeO | \(F\) | Region | Author |
|---|---|---|---|---|---|---|---|
| 1 | 2177 | Hornblende*) | 6.70 | 11.30 | 0.59 | Middle Urals. Amphibolitized gabbro. | N. V. Samoilova |
| 2 | 2188 | Hornblende*) | 5.00 | 14.54 | 0.34 | Central Asia, southwestern slope of the Kuramin Range. From granodiorites. | O. P. Eliseeva |
| 3 | 2130 | Hornblende | 4.69 | 6.31 | 0.74 | Mountain Shoria. Verkhne-Kondomsky granodiorite massif. | B. F. Nifantov |
| 4 | — | Hornblende**) | 7.92 | 17.05 | 0.46 | Southern Urals. Kusinsky massif | I. D. Borneman-Starynkevich; N. I. Zabavnnikova |
| 5 | — | Amphibole**) | 11.86 | 19.96 | 0.60 | Southern Urals. Gubensky massif. | G. M. Vinogradskaya |
| 6 | 2208 | Actinolite*) | 3.22 | 14.52 | 0.22 | Kazakhstan. From an ore body. | S. M. Prokhorov |
| 7 | 2225 | Tremolite*) | 1.13 | 4.21 | 0.27 | Yakutia. From skarns, depth 109 m. | A. A. Marakushev |
) Analyses of hornblendes are taken from the handbook of V. F. Morkovkina [3].
*) I. D. Borneman-Starynkevich [1].
Oxidation coefficient of intrusive rocks of the additional intrusive phase
The intrusive rocks of the additional intrusive phase are represented by trondhjemites (plagiogranites). They differ quite sharply from the rocks of the main phase both in mineralogical and in chemical composition (Table 4).
In appearance, the trondhjemites are white, or pinkish from weathering, medium-grained, slightly porphyritic rocks, owing to the presence in their overall mass of large, 0.4–0.8 cm, segregations of biotite, which makes up 5–7% of the total volume of the rock.
In thin section the trondhjemites are composed of quartz (25–33%), oligoclase (No. 18–20)—65–70%, biotite (1–3%), and hornblende (0.5–1%). Orthoclase in varieties not altered by feldspathization is present in an amount of 0.3–1% (Table 4).
According to six chemical analyses, the trondhjemites of the Verkhne-Kondomsky granodiorite massif contain ferrous oxide in weight percent: 1.98; 1.09; 1.69; 1.27; 1.81; 1.84 and, respectively, ferric oxide 1.09; 0.66; 0.69; 0.43; 1.34; 1.34. The coefficients \(F\), calculated from these data, are respectively 0.55; 0.60; 0.41; 0.34; 0.74; 0.73. The mean value of the coefficient \(F\) for the indicated trondhjemites is 0.56.
For trondhjemites from southern Norway, studied by V. M. Goldschmidt [7], the mean value of \(F\) from three analyses is 0.51.
For biotites from various intrusions of the USSR, according to the data of six chemical analyses from the handbook of V. F. Morkovkina, it is equal to 0.42.
Consequently, for rocks in which the dark-colored minerals are represented predominantly by biotite, the coefficient $F$ lies within the range 0.4–0.6. In individual cases its value may increase or decrease depending on the characteristics of the chemical composition of the biotites, in particular on fluctuations in their contents of ferric and ferrous iron oxides.
Table 4
Mineralogical composition of trondhjemites of the additional intrusive phase of the Verkhne-Kondomsky massif (in volume percent)
| No. | Sample number | Oligoclase | Quartz | Orthoclase | Hornblende | Biotite | Sphene | Apatite | Magnetite | Sum |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 26 | 76.0 | 22.8 | — | 0.1 | 0.6 | — | 0.1 | 0.4 | 100 |
| 2 | 9–A | 55.6 | 42.3 | 0.5 | — | 0.8 | 0.3 | — | 0.5 | 100 |
| 3 | 15 | 62.7 | 33.5 | 0.7 | 1.8 | 1.2 | — | — | 0.1 | 100 |
| 4 | 10 | 68.7 | 26.6 | 0.8 | 1.8 | 0.2 | 0.7 | 0.5 | 0.7 | 100 |
| Sum | 63.0 | 31.3 | 0.5 | 0.9 | 0.7 | 0.3 | 0.2 | 0.4 | 100 | |
| 5* | — | 44.0 | 34.4 | 0.3 | — | 10.0 | — | 0.29 | — | 100 |
*) Trondhjemite according to V. M. Goldschmidt [7]. The sum of the analysis includes clinozoisite—5%, muscovite—5%, garnet (almandine)—1%, pyrite—0.06%.
Variations of the oxidation coefficient during feldspathization
Feldspathization of the intrusive rocks of the main and additional phases of the Verkhne-Kondomsky granodiorite massif is observed [4] very distinctly. Morphologically, this process is manifested as a network of thin veinlets that form “orthoclase stockworks” in the altered rocks, as abundant metasomatic dissemination of orthoclase, and as an almost complete replacement of the original rocks by orthoclase. In the latter case, intense reddening of the rocks is observed, along with replacement of hornblende by biotite and a general decrease in the amount of dark-colored minerals, up to their complete disappearance.
Naturally, in this process the bulk iron content in the rocks decreases and the ratio of ferrous to ferric iron oxides changes. Depending on the degree of feldspathization of the rocks of the main intrusive phase of the Verkhne-Kondomsky granodiorite massif, field and laboratory studies have established a gradual change in the composition and amount of dark-colored minerals, as shown in Table 5; that is, the more strongly the rock has undergone feldspathization, the fewer dark-colored components remain in it.
With an increase in the amount of metasomatic orthoclase, hornblende is transformed into biotite, a fine hematite dust is precipitated, imparting a flesh-red color to the feldspathized rocks, and the ratio $F = \mathrm{Fe_2O_3} : \mathrm{FeO}$ changes toward a decrease (Table 6) during biotitization of hornblendes. Then $F$ increases again owing to oxidation of FeO to $\mathrm{Fe_2O_3}$.
Table 5
Change in the composition of intrusive rocks during feldspathization
| Rock color | Stage of feldspathization | Orthoclase content, % | Name of the dark-colored mineral | Average content of dark-colored mineral, % |
|---|---|---|---|---|
| Gray | Rocks unaltered by feldspathization | 2–4 | Predominantly hornblende | 10–15 |
| Pink | Weak feldspathization | 5–10 | Hornblende, biotite | 10–15 |
| Deep pink | Moderate feldspathization | 10–15 | Biotite, hornblende | 5–10 |
| Flesh-red | Strong feldspathization | 15–25 | Biotite | 3–5 |
Table 6
Variations of \(F\) during feldspathization of intrusive rocks of the main intrusive phase of the Verkhne-Kondomsky massif
| No. | Sample number | SiO₂ | Al₂O₃ | Fe₂O₃ | FeO | K₂O | Na₂O | \(F\) |
|---|---|---|---|---|---|---|---|---|
| 1 | 2244 | 65,02 | 16,59 | 2,02 | 2,75 | 2,33 | 5,00 | 0,74 |
| 2 | 2244;2 | 66,16 | 16,41 | 1,27 | 2,82 | 3,27 | 4,53 | 0,45 |
| 3 | 343 | 57,23 | 17,76 | 1,93 | 3,93 | 4,07 | 3,67 | 0,49 |
| 4 | 2244;4 | 59,15 | 19,39 | 1,92 | 2,68 | 7,43 | 5,00 | 0,72 |
- Unaltered quartz diorite. 2, 3. Moderately feldspathized quartz diorites. 4. Strongly feldspathized quartz diorite.
Variations of the oxidation coefficient during magnesian metasomatism
As already noted [4], within the intrusive field there are metasomatic gabbro-diorites and hornblendites, formed in the endocontacts of the massif as a result of the progressive introduction of magnesium, calcium, and iron and the recrystallization of the original rocks. Below are given, in order of increasing magnesium oxide content, analyses of metasomatic gabbro-diorites and hornblendites and the calculated value of \(F\).
As can be seen from Table 7, the ratio \(F\) practically does not change during magnesian metasomatism in the process of an increase in the amount of hornblende and its recrystallization with the formation of giant-grained almost monomineralic hornblendites. At the same time, \(F\) of the metasomatic gabbro-diorites and hornblendites (0,72) is numerically almost equal to the value of \(F\) of the intrusive rocks of the main phase of emplacement (0,75) of the Verkhne-Kondomsky massif. This apparently indicates a single source of material for the formation of metasomatic and magmatic hornblendes and points to approximately identical physicochemical conditions of their crystallization, although in geological time these minerals are of different ages.
Table 7
Variations of \(F\) during magnesian metasomatism of the endocontact parts of the Verkhne-Kondomsky massif
| No. | Sample number | SiO₂ | Fe₂O₃ | FeO | MgO | \(F\) |
|---|---|---|---|---|---|---|
| 1 | 2244 | 65,02 | 2,02 | 2,75 | 1,27 | 0,74 |
| 2 | 2284,1 | 55,83 | 2,15 | 4,70 | 3,30 | 0,46 |
| 3 | 2284/2 | 53,68 | 3,52 | 5,01 | 4,19 | 0,70 |
| 4 | 2072 | 45,34 | 5,07 | 6,33 | 5,25 | 0,80 |
| 5 | 2026 | 46,10 | 4,14 | 6,10 | 5,78 | 0,68 |
| 6 | 54 | 46,03 | 5,22 | 5,59 | 6,81 | 0,72 |
| 7 | 2284,3 | 46,30 | 2,48 | 6,87 | 10,88 | 0,36 |
| 8 | 2130 | 45,69 | 4,69 | 6,31 | 15,06 | 0,74 |
- Quartz diorite. 2—6. Gabbro-diorites. 7—8. Hornblendites.
Oxidation coefficients of the dike facies of the Verkhne-Kondomsky intrusion
In the field of the Verkhne-Kondomsky intrusive massif, dikes of different composition, structure, and age are widely distributed. Among the dike rocks there are aplites, microdiorites, spessartites and kersantites, and oligoclase labradorite and pyroxene porphyrites. Values of the oxidation coefficient for the dike rocks are given in Table 8.
Table 8
Oxidation coefficient of dike formations of the Verkhne-Kondomsky granodiorite massif
| No. | Sample number | SiO₂ | Fe₂O₃ | FeO | MgO | F |
|---|---|---|---|---|---|---|
| 1 | 2082 | 75,96 | 0,18 | 1,52 | 0,04 | 0,12 |
| 2 | 2060 | 75,86 | 0,03 | 1,75 | tr. | 0,02 |
| 3 | 2153 | 75,35 | 0,34 | 1,55 | 0,29 | 0,22 |
| 4 | 2170 | 64,69 | 1,21 | 2,96 | 2,08 | 0,41 |
| 5 | 2163 | 62,84 | 2,29 | 3,18 | 1,96 | 0,72 |
| 6 | 2081,1 | 50,90 | 2,46 | 7,36 | 4,95 | 0,34 |
| 7 | 2039,2 | 57,85 | 0,40 | 0,96 | 0,20 | 0,42 |
| 8 | 2026/2 | 57,15 | 0,33 | 1,04 | 0,20 | 0,32 |
| 9 | 2063 | 51,40 | 2,75 | 7,52 | 5,63 | 0,37 |
1—3. Aplites. 4—6. Diorite porphyrites. 7—8. Oligoclasites.
9. Pyroxene labradorite.
From the factual material set forth above it follows that the oxidation coefficient \(F\) depends on the mineralogical composition of the rocks. On the other hand, the value of \(F\) for rocks of the Verkhne-Kondomsky granodiorite massif decreases from the main intrusive phase (\(F = 0,75\)) to addi-
…initial phase of intrusion ($F = 0.5$) and to vein formations ($F = 0.1$–$0.4$). Thus, the oxidation coefficient gradually decreases from the earlier phases of intrusion to the later products of intrusive activity—dikes. Within the dike group itself, a decrease in the value of $F$ is clearly observed from earlier, in terms of time of formation, basic dikes to later, younger aplites.
The higher numerical values of the oxidation coefficient in the early phases of intrusion can apparently be explained by magmatic assimilation of free oxygen from the enclosing rocks.
As magma is intruded, part of the free oxygen contained in the enclosing rocks, under the influence of magmatic heat, migrates along fractures into the overlying rocks. The remaining oxygen may be assimilated by the magma. In this process, a certain amount of ferrous oxide is converted into ferric oxide; i.e., the oxidation coefficient of the first (main) phase of intrusion increases. Subsequent portions of magma, corresponding to the later phases of intrusion of the given intrusive body, receive from the enclosing strata a smaller amount of free oxygen, in connection with which their rocks will be distinguished by numerically lower values of the oxidation coefficient in comparison with the formations of the main phase. Consequently, determination of the oxidation state ($F$) of intrusive rocks may to a certain extent be used as an additional means for determining the sequence of intrusion of intrusive formations.
REFERENCES
-
I. D. Borneman-Starynkevich. Handbook for Calculating Mineral Formulas. Publishing House “Nauka,” Moscow, 1964.
-
Yu. S. Kutsev. On certain aspects of the petrogenetic role of the ratio $\mathrm{Fe_2O_3} : \mathrm{FeO}$ in magmatic rocks. Izv. AN SSSR, Geological Series, No. 11, 1964.
-
V. F. Morkovkina. Chemical Analyses of Igneous Rocks. Publishing House “Nauka,” Moscow, 1964.
-
B. F. Nifantov. On the Verkhne-Kondomsky granodiorite massif. Proceedings of the Tomsk Polytechnic Institute, vol. 127, 1964.
-
S. I. Shukin. On the possibility of applying the iron oxidation coefficient for the classification of volcanic rocks. Geochemistry, No. 8, 1963.
-
H. P. Taylor, S. Epstein. Relationship between $\mathrm{O}^{18}/\mathrm{O}^{16}$ ratios in coexisting minerals of igneous and metamorphic rocks. Bull. of the Geol. Soc. of America, vol. 71, No. 4, vol. 73, No. 6, 1962.
-
V. M. Goldschmidt. Geologisch petrographische Studien im Hochgebirge des Südlichen Norwegens. Kristiania, 1921.