Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes
Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent...
Ausführliche Beschreibung
Gespeichert in:
| Autor*in: |
Jung, S. [verfasserIn] Mezger, K. [verfasserIn] |
|---|
| Format: |
E-Artikel |
|---|
| Erschienen: |
Oxford, UK: Blackwell Science Inc ; 2001 |
|---|
| Schlagwörter: |
|---|
| Umfang: |
Online-Ressource |
|---|
| Reproduktion: |
2001 ; Blackwell Publishing Journal Backfiles 1879-2005 |
|---|---|
| Übergeordnetes Werk: |
In: Journal of metamorphic geology - Oxford [u.a.] : Wiley-Blackwell, 1983, 19(2001), 1, Seite 0 |
| Übergeordnetes Werk: |
volume:19 ; year:2001 ; number:1 ; pages:0 |
| Links: |
|---|
| DOI / URN: |
10.1046/j.0263-4929.2000.00297.x |
|---|
| Katalog-ID: |
NLEJ243174322 |
|---|
| LEADER | 01000caa a22002652 4500 | ||
|---|---|---|---|
| 001 | NLEJ243174322 | ||
| 003 | DE-627 | ||
| 005 | 20210707173523.0 | ||
| 007 | cr uuu---uuuuu | ||
| 008 | 120427s2001 xx |||||o 00| ||und c | ||
| 024 | 7 | |a 10.1046/j.0263-4929.2000.00297.x |2 doi | |
| 035 | |a (DE-627)NLEJ243174322 | ||
| 040 | |a DE-627 |b ger |c DE-627 |e rakwb | ||
| 100 | 1 | |a Jung, S. |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| 264 | 1 | |a Oxford, UK |b Blackwell Science Inc |c 2001 | |
| 300 | |a Online-Ressource | ||
| 336 | |a nicht spezifiziert |b zzz |2 rdacontent | ||
| 337 | |a nicht spezifiziert |b z |2 rdamedia | ||
| 338 | |a nicht spezifiziert |b zu |2 rdacarrier | ||
| 520 | |a Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. | ||
| 533 | |d 2001 |f Blackwell Publishing Journal Backfiles 1879-2005 |7 |2001|||||||||| | ||
| 650 | 4 | |a Sm–Nd garnet | |
| 650 | 4 | |a U–Pb monazite | |
| 650 | 4 | |a geochronology | |
| 650 | 4 | |a Damara orogen | |
| 650 | 4 | |a migmatites | |
| 700 | 1 | |a Mezger, K. |e verfasserin |4 aut | |
| 773 | 0 | 8 | |i In |t Journal of metamorphic geology |d Oxford [u.a.] : Wiley-Blackwell, 1983 |g 19(2001), 1, Seite 0 |h Online-Ressource |w (DE-627)NLEJ243926766 |w (DE-600)2020499-1 |x 1525-1314 |7 nnns |
| 773 | 1 | 8 | |g volume:19 |g year:2001 |g number:1 |g pages:0 |
| 856 | 4 | 0 | |u http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x |q text/html |x Verlag |z Deutschlandweit zugänglich |3 Volltext |
| 912 | |a GBV_USEFLAG_U | ||
| 912 | |a ZDB-1-DJB | ||
| 912 | |a GBV_NL_ARTICLE | ||
| 951 | |a AR | ||
| 952 | |d 19 |j 2001 |e 1 |h 0 | ||
| author_variant |
s j sj k m km |
|---|---|
| matchkey_str |
article:15251314:2001----::ecrnlgimgaieamdpadbrtdfotertrzidmrblnmbamlctosoplpaeee |
| hierarchy_sort_str |
2001 |
| publishDate |
2001 |
| allfields |
10.1046/j.0263-4929.2000.00297.x doi (DE-627)NLEJ243174322 DE-627 ger DE-627 rakwb Jung, S. verfasserin aut Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Oxford, UK Blackwell Science Inc 2001 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. 2001 Blackwell Publishing Journal Backfiles 1879-2005 |2001|||||||||| Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites Mezger, K. verfasserin aut In Journal of metamorphic geology Oxford [u.a.] : Wiley-Blackwell, 1983 19(2001), 1, Seite 0 Online-Ressource (DE-627)NLEJ243926766 (DE-600)2020499-1 1525-1314 nnns volume:19 year:2001 number:1 pages:0 http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 19 2001 1 0 |
| spelling |
10.1046/j.0263-4929.2000.00297.x doi (DE-627)NLEJ243174322 DE-627 ger DE-627 rakwb Jung, S. verfasserin aut Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Oxford, UK Blackwell Science Inc 2001 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. 2001 Blackwell Publishing Journal Backfiles 1879-2005 |2001|||||||||| Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites Mezger, K. verfasserin aut In Journal of metamorphic geology Oxford [u.a.] : Wiley-Blackwell, 1983 19(2001), 1, Seite 0 Online-Ressource (DE-627)NLEJ243926766 (DE-600)2020499-1 1525-1314 nnns volume:19 year:2001 number:1 pages:0 http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 19 2001 1 0 |
| allfields_unstemmed |
10.1046/j.0263-4929.2000.00297.x doi (DE-627)NLEJ243174322 DE-627 ger DE-627 rakwb Jung, S. verfasserin aut Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Oxford, UK Blackwell Science Inc 2001 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. 2001 Blackwell Publishing Journal Backfiles 1879-2005 |2001|||||||||| Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites Mezger, K. verfasserin aut In Journal of metamorphic geology Oxford [u.a.] : Wiley-Blackwell, 1983 19(2001), 1, Seite 0 Online-Ressource (DE-627)NLEJ243926766 (DE-600)2020499-1 1525-1314 nnns volume:19 year:2001 number:1 pages:0 http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 19 2001 1 0 |
| allfieldsGer |
10.1046/j.0263-4929.2000.00297.x doi (DE-627)NLEJ243174322 DE-627 ger DE-627 rakwb Jung, S. verfasserin aut Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Oxford, UK Blackwell Science Inc 2001 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. 2001 Blackwell Publishing Journal Backfiles 1879-2005 |2001|||||||||| Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites Mezger, K. verfasserin aut In Journal of metamorphic geology Oxford [u.a.] : Wiley-Blackwell, 1983 19(2001), 1, Seite 0 Online-Ressource (DE-627)NLEJ243926766 (DE-600)2020499-1 1525-1314 nnns volume:19 year:2001 number:1 pages:0 http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 19 2001 1 0 |
| allfieldsSound |
10.1046/j.0263-4929.2000.00297.x doi (DE-627)NLEJ243174322 DE-627 ger DE-627 rakwb Jung, S. verfasserin aut Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Oxford, UK Blackwell Science Inc 2001 Online-Ressource nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. 2001 Blackwell Publishing Journal Backfiles 1879-2005 |2001|||||||||| Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites Mezger, K. verfasserin aut In Journal of metamorphic geology Oxford [u.a.] : Wiley-Blackwell, 1983 19(2001), 1, Seite 0 Online-Ressource (DE-627)NLEJ243926766 (DE-600)2020499-1 1525-1314 nnns volume:19 year:2001 number:1 pages:0 http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x text/html Verlag Deutschlandweit zugänglich Volltext GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE AR 19 2001 1 0 |
| source |
In Journal of metamorphic geology 19(2001), 1, Seite 0 volume:19 year:2001 number:1 pages:0 |
| sourceStr |
In Journal of metamorphic geology 19(2001), 1, Seite 0 volume:19 year:2001 number:1 pages:0 |
| format_phy_str_mv |
Article |
| institution |
findex.gbv.de |
| topic_facet |
Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites |
| isfreeaccess_bool |
false |
| container_title |
Journal of metamorphic geology |
| authorswithroles_txt_mv |
Jung, S. @@aut@@ Mezger, K. @@aut@@ |
| publishDateDaySort_date |
2001-01-01T00:00:00Z |
| hierarchy_top_id |
NLEJ243926766 |
| id |
NLEJ243174322 |
| fullrecord |
<?xml version="1.0" encoding="UTF-8"?><collection xmlns="http://www.loc.gov/MARC21/slim"><record><leader>01000caa a22002652 4500</leader><controlfield tag="001">NLEJ243174322</controlfield><controlfield tag="003">DE-627</controlfield><controlfield tag="005">20210707173523.0</controlfield><controlfield tag="007">cr uuu---uuuuu</controlfield><controlfield tag="008">120427s2001 xx |||||o 00| ||und c</controlfield><datafield tag="024" ind1="7" ind2=" "><subfield code="a">10.1046/j.0263-4929.2000.00297.x</subfield><subfield code="2">doi</subfield></datafield><datafield tag="035" ind1=" " ind2=" "><subfield code="a">(DE-627)NLEJ243174322</subfield></datafield><datafield tag="040" ind1=" " ind2=" "><subfield code="a">DE-627</subfield><subfield code="b">ger</subfield><subfield code="c">DE-627</subfield><subfield code="e">rakwb</subfield></datafield><datafield tag="100" ind1="1" ind2=" "><subfield code="a">Jung, S.</subfield><subfield code="e">verfasserin</subfield><subfield code="4">aut</subfield></datafield><datafield tag="245" ind1="1" ind2="0"><subfield code="a">Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes</subfield></datafield><datafield tag="264" ind1=" " ind2="1"><subfield code="a">Oxford, UK</subfield><subfield code="b">Blackwell Science Inc</subfield><subfield code="c">2001</subfield></datafield><datafield tag="300" ind1=" " ind2=" "><subfield code="a">Online-Ressource</subfield></datafield><datafield tag="336" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">zzz</subfield><subfield code="2">rdacontent</subfield></datafield><datafield tag="337" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">z</subfield><subfield code="2">rdamedia</subfield></datafield><datafield tag="338" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">zu</subfield><subfield code="2">rdacarrier</subfield></datafield><datafield tag="520" ind1=" " ind2=" "><subfield code="a">Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events.</subfield></datafield><datafield tag="533" ind1=" " ind2=" "><subfield code="d">2001</subfield><subfield code="f">Blackwell Publishing Journal Backfiles 1879-2005</subfield><subfield code="7">|2001||||||||||</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Sm–Nd garnet</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">U–Pb monazite</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">geochronology</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Damara orogen</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">migmatites</subfield></datafield><datafield tag="700" ind1="1" ind2=" "><subfield code="a">Mezger, K.</subfield><subfield code="e">verfasserin</subfield><subfield code="4">aut</subfield></datafield><datafield tag="773" ind1="0" ind2="8"><subfield code="i">In</subfield><subfield code="t">Journal of metamorphic geology</subfield><subfield code="d">Oxford [u.a.] : Wiley-Blackwell, 1983</subfield><subfield code="g">19(2001), 1, Seite 0</subfield><subfield code="h">Online-Ressource</subfield><subfield code="w">(DE-627)NLEJ243926766</subfield><subfield code="w">(DE-600)2020499-1</subfield><subfield code="x">1525-1314</subfield><subfield code="7">nnns</subfield></datafield><datafield tag="773" ind1="1" ind2="8"><subfield code="g">volume:19</subfield><subfield code="g">year:2001</subfield><subfield code="g">number:1</subfield><subfield code="g">pages:0</subfield></datafield><datafield tag="856" ind1="4" ind2="0"><subfield code="u">http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x</subfield><subfield code="q">text/html</subfield><subfield code="x">Verlag</subfield><subfield code="z">Deutschlandweit zugänglich</subfield><subfield code="3">Volltext</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">GBV_USEFLAG_U</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">ZDB-1-DJB</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">GBV_NL_ARTICLE</subfield></datafield><datafield tag="951" ind1=" " ind2=" "><subfield code="a">AR</subfield></datafield><datafield tag="952" ind1=" " ind2=" "><subfield code="d">19</subfield><subfield code="j">2001</subfield><subfield code="e">1</subfield><subfield code="h">0</subfield></datafield></record></collection>
|
| series2 |
Blackwell Publishing Journal Backfiles 1879-2005 |
| author |
Jung, S. |
| spellingShingle |
Jung, S. misc Sm–Nd garnet misc U–Pb monazite misc geochronology misc Damara orogen misc migmatites Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| authorStr |
Jung, S. |
| ppnlink_with_tag_str_mv |
@@773@@(DE-627)NLEJ243926766 |
| format |
electronic Article |
| delete_txt_mv |
keep |
| author_role |
aut aut |
| collection |
NL |
| publishPlace |
Oxford, UK |
| remote_str |
true |
| illustrated |
Not Illustrated |
| issn |
1525-1314 |
| topic_title |
Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes Sm–Nd garnet U–Pb monazite geochronology Damara orogen migmatites |
| publisher |
Blackwell Science Inc |
| publisherStr |
Blackwell Science Inc |
| topic |
misc Sm–Nd garnet misc U–Pb monazite misc geochronology misc Damara orogen misc migmatites |
| topic_unstemmed |
misc Sm–Nd garnet misc U–Pb monazite misc geochronology misc Damara orogen misc migmatites |
| topic_browse |
misc Sm–Nd garnet misc U–Pb monazite misc geochronology misc Damara orogen misc migmatites |
| format_facet |
Elektronische Aufsätze Aufsätze Elektronische Ressource |
| format_main_str_mv |
Text Zeitschrift/Artikel |
| carriertype_str_mv |
zu |
| hierarchy_parent_title |
Journal of metamorphic geology |
| hierarchy_parent_id |
NLEJ243926766 |
| hierarchy_top_title |
Journal of metamorphic geology |
| isfreeaccess_txt |
false |
| familylinks_str_mv |
(DE-627)NLEJ243926766 (DE-600)2020499-1 |
| title |
Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| ctrlnum |
(DE-627)NLEJ243174322 |
| title_full |
Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| author_sort |
Jung, S. |
| journal |
Journal of metamorphic geology |
| journalStr |
Journal of metamorphic geology |
| isOA_bool |
false |
| recordtype |
marc |
| publishDateSort |
2001 |
| contenttype_str_mv |
zzz |
| container_start_page |
0 |
| author_browse |
Jung, S. Mezger, K. |
| container_volume |
19 |
| physical |
Online-Ressource |
| format_se |
Elektronische Aufsätze |
| author-letter |
Jung, S. |
| doi_str_mv |
10.1046/j.0263-4929.2000.00297.x |
| author2-role |
verfasserin |
| title_sort |
geochronology in migmatites – a sm–nd, u–pb and rb–sr study from the proterozoic damara belt (namibia): implications for polyphase development of migmatites in high-grade terranes |
| title_auth |
Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| abstract |
Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. |
| abstractGer |
Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. |
| abstract_unstemmed |
Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events. |
| collection_details |
GBV_USEFLAG_U ZDB-1-DJB GBV_NL_ARTICLE |
| container_issue |
1 |
| title_short |
Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes |
| url |
http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x |
| remote_bool |
true |
| author2 |
Mezger, K. |
| author2Str |
Mezger, K. |
| ppnlink |
NLEJ243926766 |
| mediatype_str_mv |
z |
| isOA_txt |
false |
| hochschulschrift_bool |
false |
| doi_str |
10.1046/j.0263-4929.2000.00297.x |
| up_date |
2024-07-06T04:34:38.631Z |
| _version_ |
1803802880122028032 |
| fullrecord_marcxml |
<?xml version="1.0" encoding="UTF-8"?><collection xmlns="http://www.loc.gov/MARC21/slim"><record><leader>01000caa a22002652 4500</leader><controlfield tag="001">NLEJ243174322</controlfield><controlfield tag="003">DE-627</controlfield><controlfield tag="005">20210707173523.0</controlfield><controlfield tag="007">cr uuu---uuuuu</controlfield><controlfield tag="008">120427s2001 xx |||||o 00| ||und c</controlfield><datafield tag="024" ind1="7" ind2=" "><subfield code="a">10.1046/j.0263-4929.2000.00297.x</subfield><subfield code="2">doi</subfield></datafield><datafield tag="035" ind1=" " ind2=" "><subfield code="a">(DE-627)NLEJ243174322</subfield></datafield><datafield tag="040" ind1=" " ind2=" "><subfield code="a">DE-627</subfield><subfield code="b">ger</subfield><subfield code="c">DE-627</subfield><subfield code="e">rakwb</subfield></datafield><datafield tag="100" ind1="1" ind2=" "><subfield code="a">Jung, S.</subfield><subfield code="e">verfasserin</subfield><subfield code="4">aut</subfield></datafield><datafield tag="245" ind1="1" ind2="0"><subfield code="a">Geochronology in migmatites – a Sm–Nd, U–Pb and Rb–Sr study from the Proterozoic Damara belt (Namibia): implications for polyphase development of migmatites in high-grade terranes</subfield></datafield><datafield tag="264" ind1=" " ind2="1"><subfield code="a">Oxford, UK</subfield><subfield code="b">Blackwell Science Inc</subfield><subfield code="c">2001</subfield></datafield><datafield tag="300" ind1=" " ind2=" "><subfield code="a">Online-Ressource</subfield></datafield><datafield tag="336" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">zzz</subfield><subfield code="2">rdacontent</subfield></datafield><datafield tag="337" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">z</subfield><subfield code="2">rdamedia</subfield></datafield><datafield tag="338" ind1=" " ind2=" "><subfield code="a">nicht spezifiziert</subfield><subfield code="b">zu</subfield><subfield code="2">rdacarrier</subfield></datafield><datafield tag="520" ind1=" " ind2=" "><subfield code="a">Sm–Nd (garnet), U–Pb (monazite) and Rb–Sr (biotite) ages from a composite migmatite sample (Damara orogen, Namibia) constrain the time of high-grade regional metamorphism and the duration of regional metamorphic events. Sm–Nd garnet whole-rock ages for a strongly restitic melanosome and an adjacent intrusive leucosome yield ages of 534±5, 528±11 and 539±8 Ma. These results provide substantial evidence for pre-500 Ma Pan-African regional metamorphism and melting for this segment of the orogen. Other parts of the migmatite yield younger Sm–Nd ages of 488±9 Ma for melanosome and 496±10, 492±5 and 511±16 Ma for the corresponding leucosomes. Garnet from one xenolith from the leucosomes yields an age of 497±2 Ma. Major element compostions of garnet are different in terms of absolute abundances of pyrope and spessartine components, but the flat shape of the elemental patterns suggests late-stage retrograde equilibration. Rare earth element compositions of the garnet from the different layers are similar except for garnet from the intrusive leucosome suggesting that they grew in different environments. Monazite from the leucosomes is reversely discordant and records 207Pb/235U ages between 536 and 529 Ma, indicating that this monazite represents incorporated residual material from the first melting event. Monazite from the mesosome MES 2 and the melanosome MEL 3 gives 207Pb/235U ages of 523 and 526 Ma, and 529 and 531 Ma, respectively, which probably indicates another thermal event. Previously published 207Pb/235U monazite data give ages between 525 and 521 Ma for composite migmatites, and 521 and 518 Ma for monazite from neosomes. Monazite from granitic to granodioritic veins indicates another thermal event at 507–505 Ma. These ages are also recorded in 207Pb/235U monazite data of 508 Ma from the metasediment MET 1 from the migmatite and also in the Sm–Nd garnet ages obtained in this study. Taken together, these ages indicate that high-grade metamorphism started at c. 535 Ma (or earlier) and was followed by thermal events at c. 520 Ma and c. 505 Ma. The latter event is probably connected with the intrusion of a large igneous body (Donkerhoek granite) for which so far only imprecise Rb–Sr whole-rock data of 520±15 Ma are available. Rb–Sr biotite ages from the different layers of the migmatite are 488, 469 and 473 Ma. These different ages indicate late-stage disturbance of the Rb–Sr isotopic system on the sub-sample scale. Nevertheless, these ages are close to the youngest Sm–Nd garnet ages, indicating rapid cooling rates between 13 and 20°C Ma−1 and fast uplift of this segment of the crust. Similar Sm–Nd garnet and U–Pb monazite ages suggest that the closure temperatures for both isotopic systems are not very different in this case and are probably similar or higher than the previously estimated peak metamorphic temperatures of 730±30°C. The preservation of restitic monazite in leucosomes indicates that dissolution of monazite in felsic water-undersaturated peraluminous melts can be sluggish. This study shows that geochronological data from migmatites can record polymetamorphic episodes in high-grade terranes that often contain cryptic evidence for the nature and timing of early metamorphic events.</subfield></datafield><datafield tag="533" ind1=" " ind2=" "><subfield code="d">2001</subfield><subfield code="f">Blackwell Publishing Journal Backfiles 1879-2005</subfield><subfield code="7">|2001||||||||||</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Sm–Nd garnet</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">U–Pb monazite</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">geochronology</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">Damara orogen</subfield></datafield><datafield tag="650" ind1=" " ind2="4"><subfield code="a">migmatites</subfield></datafield><datafield tag="700" ind1="1" ind2=" "><subfield code="a">Mezger, K.</subfield><subfield code="e">verfasserin</subfield><subfield code="4">aut</subfield></datafield><datafield tag="773" ind1="0" ind2="8"><subfield code="i">In</subfield><subfield code="t">Journal of metamorphic geology</subfield><subfield code="d">Oxford [u.a.] : Wiley-Blackwell, 1983</subfield><subfield code="g">19(2001), 1, Seite 0</subfield><subfield code="h">Online-Ressource</subfield><subfield code="w">(DE-627)NLEJ243926766</subfield><subfield code="w">(DE-600)2020499-1</subfield><subfield code="x">1525-1314</subfield><subfield code="7">nnns</subfield></datafield><datafield tag="773" ind1="1" ind2="8"><subfield code="g">volume:19</subfield><subfield code="g">year:2001</subfield><subfield code="g">number:1</subfield><subfield code="g">pages:0</subfield></datafield><datafield tag="856" ind1="4" ind2="0"><subfield code="u">http://dx.doi.org/10.1046/j.0263-4929.2000.00297.x</subfield><subfield code="q">text/html</subfield><subfield code="x">Verlag</subfield><subfield code="z">Deutschlandweit zugänglich</subfield><subfield code="3">Volltext</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">GBV_USEFLAG_U</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">ZDB-1-DJB</subfield></datafield><datafield tag="912" ind1=" " ind2=" "><subfield code="a">GBV_NL_ARTICLE</subfield></datafield><datafield tag="951" ind1=" " ind2=" "><subfield code="a">AR</subfield></datafield><datafield tag="952" ind1=" " ind2=" "><subfield code="d">19</subfield><subfield code="j">2001</subfield><subfield code="e">1</subfield><subfield code="h">0</subfield></datafield></record></collection>
|
| score |
7.401086 |