MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE)
In the Chernorud granulite zone in the Olkhon region of West Pribaikalie, we studied gabbro‐pyroxenites composing tectonic plates (Chernorud, Tonta) and synmetamorphic intrusive bodies (Ulan‐Khargana), as well as nu‐ merous disintegrated boudins and inclusions embedded in the metamorphic matrix. Bas...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust
2017-06-01
|
| Series: | Геодинамика и тектонофизика |
| Subjects: | |
| Online Access: | https://www.gt-crust.ru/jour/article/view/361 |
| _version_ | 1797855748405854208 |
|---|---|
| author | A. G. Vladimirov A. S. Mekhonoshin S. V. Khromykh E. I. Mikheev A. V. Travin N. I. Volkova T. B. Kolotilina Yu. A. Davydenko E. V. Borodina V. V. Khlestov |
| author_facet | A. G. Vladimirov A. S. Mekhonoshin S. V. Khromykh E. I. Mikheev A. V. Travin N. I. Volkova T. B. Kolotilina Yu. A. Davydenko E. V. Borodina V. V. Khlestov |
| author_sort | A. G. Vladimirov |
| collection | DOAJ |
| description | In the Chernorud granulite zone in the Olkhon region of West Pribaikalie, we studied gabbro‐pyroxenites composing tectonic plates (Chernorud, Tonta) and synmetamorphic intrusive bodies (Ulan‐Khargana), as well as nu‐ merous disintegrated boudins and inclusions embedded in the metamorphic matrix. Based on the results of compara‐ tive analysis of the chemical compositions, the gabbro‐pyroxenites are classified into a single island‐arc tholeiitic se‐ ries. The COMAGMAT software was used to simulate this series and to estimate the initial composition of the parent magma (magnesian basalt: SiO2=46.0 wt. %, TiO2=0.8 wt. %, Al2O3=15.3 wt. %, ΣFeO=9.0 wt. %, MnO=0.15 wt. %, MgO=10.5 wt. %, CaO=17.0 wt. %, Na2O=1.0 wt. %, K2O=0.2 wt. %, P2O5=0.05 wt. %, total = 100.0 %, Mg# = 67.5 %). It is concluded that the granulite metamorphism (P=7.7 to 8.6 kbar, T=770 to 820 °C) was due not only to dipping of the initial sedimentary‐volcanic series to a depth of 25–28 km, but also to the presence of a deep chamber of magnesian basalt magma. In our estimations, garnet‐pyroxenites (i.e. mafic rocks of the top facies in the above‐mentioned cham‐ ber) originated at P=8.0–8.3 kbar and T=900–930 °C. Considering petrology, the deep mafic chamber under the layer of granulite facies is evidenced by metamorphic magma mingling, as well as pipe‐shaped intrusions characterized by the specific morphology, internal structure and bulk rock compositions. Based on the data on the Ulan‐Khargana mas‐ sif and gabbro‐pyroxenite bodies involved in the structure of the marble melange, we propose a petrological model showing two stages of mafic injection – Stage 1: hydraulic fracturing of granulite series and the emergence of tubular structures and bodies, which are similar to kimberlite pipes or channels of different shapes; Stage 2: rising of the flu‐ idized residual alkaline melt through the emerging ‘pipes’ and fractures armored by hardened zones, which is fol‐ lowed by metamorphic magma mingling under viscous deformation conditions. The mafic magmas intruding to the level of the granulite facies facilitated the deep anatexis and formation of synmetamorphic hypersthene plagiogranites (U‐Pb isotope dating: 500–490 Ma) and high‐K stress granites. In the Chernorud granulite zone, intense ductile‐plastic and brittle‐plastic deformations accompanied the processes of metamorphism, intrusion and formation of gabbro‐ pyroxenites and the anatexis of the crustal substance. As a result, the intrusive bodies were fragmented, and specific tectonic structures termed ‘metamorphic magma‐mingling’ were formed. All the tectonic and magmatic structures were subsequently ‘sealed up’ by K‐Na synkinematic granites at the regressive stage under conditions of the amphibo‐ lite‐facies metamorphism (U‐Pb and Ar‐Ar isotope dating: 470–460 Ma). |
| first_indexed | 2024-04-09T20:28:33Z |
| format | Article |
| id | doaj.art-350811f3c23441a584e68e1cfe32f1b8 |
| institution | Directory Open Access Journal |
| issn | 2078-502X |
| language | English |
| last_indexed | 2024-04-09T20:28:33Z |
| publishDate | 2017-06-01 |
| publisher | Russian Academy of Sciences, Siberian Branch, Institute of the Earth's crust |
| record_format | Article |
| series | Геодинамика и тектонофизика |
| spelling | doaj.art-350811f3c23441a584e68e1cfe32f1b82023-03-30T20:08:02ZengRussian Academy of Sciences, Siberian Branch, Institute of the Earth's crustГеодинамика и тектонофизика2078-502X2017-06-018222326810.5800/GT-2017-8-2-0240235MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE)A. G. Vladimirov0A. S. Mekhonoshin1S. V. Khromykh2E. I. Mikheev3A. V. Travin4N. I. Volkova5T. B. Kolotilina6Yu. A. Davydenko7E. V. Borodina8V. V. Khlestov9V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS; Novosibirsk State University Tomsk State UniversityA.P. Vinogradov Institute of Geochemistry, Siberian Branch of RAS Irkutsk National Research Technical UniversityV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS Novosibirsk State UniversityV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS Novosibirsk State University Tomsk State UniversityV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS Novosibirsk State University Tomsk State UniversityV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS Novosibirsk State University Tomsk State UniversityA.P. Vinogradov Institute of Geochemistry, Siberian Branch of RAS Irkutsk National Research Technical UniversityIrkutsk National Research Technical UniversityV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RASV.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of RAS Novosibirsk State UniversityIn the Chernorud granulite zone in the Olkhon region of West Pribaikalie, we studied gabbro‐pyroxenites composing tectonic plates (Chernorud, Tonta) and synmetamorphic intrusive bodies (Ulan‐Khargana), as well as nu‐ merous disintegrated boudins and inclusions embedded in the metamorphic matrix. Based on the results of compara‐ tive analysis of the chemical compositions, the gabbro‐pyroxenites are classified into a single island‐arc tholeiitic se‐ ries. The COMAGMAT software was used to simulate this series and to estimate the initial composition of the parent magma (magnesian basalt: SiO2=46.0 wt. %, TiO2=0.8 wt. %, Al2O3=15.3 wt. %, ΣFeO=9.0 wt. %, MnO=0.15 wt. %, MgO=10.5 wt. %, CaO=17.0 wt. %, Na2O=1.0 wt. %, K2O=0.2 wt. %, P2O5=0.05 wt. %, total = 100.0 %, Mg# = 67.5 %). It is concluded that the granulite metamorphism (P=7.7 to 8.6 kbar, T=770 to 820 °C) was due not only to dipping of the initial sedimentary‐volcanic series to a depth of 25–28 km, but also to the presence of a deep chamber of magnesian basalt magma. In our estimations, garnet‐pyroxenites (i.e. mafic rocks of the top facies in the above‐mentioned cham‐ ber) originated at P=8.0–8.3 kbar and T=900–930 °C. Considering petrology, the deep mafic chamber under the layer of granulite facies is evidenced by metamorphic magma mingling, as well as pipe‐shaped intrusions characterized by the specific morphology, internal structure and bulk rock compositions. Based on the data on the Ulan‐Khargana mas‐ sif and gabbro‐pyroxenite bodies involved in the structure of the marble melange, we propose a petrological model showing two stages of mafic injection – Stage 1: hydraulic fracturing of granulite series and the emergence of tubular structures and bodies, which are similar to kimberlite pipes or channels of different shapes; Stage 2: rising of the flu‐ idized residual alkaline melt through the emerging ‘pipes’ and fractures armored by hardened zones, which is fol‐ lowed by metamorphic magma mingling under viscous deformation conditions. The mafic magmas intruding to the level of the granulite facies facilitated the deep anatexis and formation of synmetamorphic hypersthene plagiogranites (U‐Pb isotope dating: 500–490 Ma) and high‐K stress granites. In the Chernorud granulite zone, intense ductile‐plastic and brittle‐plastic deformations accompanied the processes of metamorphism, intrusion and formation of gabbro‐ pyroxenites and the anatexis of the crustal substance. As a result, the intrusive bodies were fragmented, and specific tectonic structures termed ‘metamorphic magma‐mingling’ were formed. All the tectonic and magmatic structures were subsequently ‘sealed up’ by K‐Na synkinematic granites at the regressive stage under conditions of the amphibo‐ lite‐facies metamorphism (U‐Pb and Ar‐Ar isotope dating: 470–460 Ma).https://www.gt-crust.ru/jour/article/view/361granulite metamorphismsynmetamorphic gabbro‐pyroxenitehypersthene plagiogranitestress granitemantle‐crust interactionmetamorphic magma‐minglingchernorud granulite zoneolknon regionwest pribaikalie |
| spellingShingle | A. G. Vladimirov A. S. Mekhonoshin S. V. Khromykh E. I. Mikheev A. V. Travin N. I. Volkova T. B. Kolotilina Yu. A. Davydenko E. V. Borodina V. V. Khlestov MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) Геодинамика и тектонофизика granulite metamorphism synmetamorphic gabbro‐pyroxenite hypersthene plagiogranite stress granite mantle‐crust interaction metamorphic magma‐mingling chernorud granulite zone olknon region west pribaikalie |
| title | MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) |
| title_full | MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) |
| title_fullStr | MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) |
| title_full_unstemmed | MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) |
| title_short | MECHANISMS OF MANTLE‐CRUST INTERACTION AT DEEP LEVELS OF COLLISION OROGENS (CASE OF THE OLKHON REGION, WEST PRIBAIKALIE) |
| title_sort | mechanisms of mantle crust interaction at deep levels of collision orogens case of the olkhon region west pribaikalie |
| topic | granulite metamorphism synmetamorphic gabbro‐pyroxenite hypersthene plagiogranite stress granite mantle‐crust interaction metamorphic magma‐mingling chernorud granulite zone olknon region west pribaikalie |
| url | https://www.gt-crust.ru/jour/article/view/361 |
| work_keys_str_mv | AT agvladimirov mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT asmekhonoshin mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT svkhromykh mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT eimikheev mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT avtravin mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT nivolkova mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT tbkolotilina mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT yuadavydenko mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT evborodina mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie AT vvkhlestov mechanismsofmantlecrustinteractionatdeeplevelsofcollisionorogenscaseoftheolkhonregionwestpribaikalie |