Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides
The North-East Greenland eclogite province is divided into a western, central and eastern block by the sinistral Storstrømmen shear zone in the west and the dextral Germania Land deformation zone in the east. A family of steep, NNW-striking dextral mylonite zones in the Danmarkshavn area are geometr...
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Cambridge University Press (CUP)
2006
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Online Access: | http://dx.doi.org/10.1017/s0016756806001968 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756806001968 |
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crcambridgeupr:10.1017/s0016756806001968 2024-09-15T18:03:28+00:00 Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides SARTINI-RIDEOUT, C. GILOTTI, J. A. McCLELLAND, W. C. 2006 http://dx.doi.org/10.1017/s0016756806001968 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756806001968 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 143, issue 4, page 431-446 ISSN 0016-7568 1469-5081 journal-article 2006 crcambridgeupr https://doi.org/10.1017/s0016756806001968 2024-07-31T04:04:15Z The North-East Greenland eclogite province is divided into a western, central and eastern block by the sinistral Storstrømmen shear zone in the west and the dextral Germania Land deformation zone in the east. A family of steep, NNW-striking dextral mylonite zones in the Danmarkshavn area are geometrically and kinematically similar to the ductile Germania Land deformation zone, located 25 km to the east. Amphibolite facies deformation at Danmarkshavn is characterized by boudinage of eclogite bodies within quartzofeldspathic host gneisses, pegmatite emplacement into the boudin necks and subsequent deformation of pegmatites parallel to gneissosity, a widespread component of dextral shear within the gneisses, and localization of strain into 10–50 m thick dextral mylonite zones. The gneisses and concordant mylonite zones are cut by a swarm of weakly to undeformed, steeply dipping, E–W-striking pegmatitic dykes. Oscillatory-zoned zircon cores from two boudin neck pegmatites give weighted mean 206 Pb/ 238 U sensitive, high mass resolution ion microprobe (SHRIMP) ages of 376 ± 5 Ma and 343 ± 7 Ma. Cathodoluminescence images of these zircons reveal complex additional rims, with ages from ranging from c . 360 to 320 Ma. Oscillatory-zoned, prismatic zircons from two late, cross-cutting pegmatites yield weighted mean 206 Pb/ 238 U SHRIMP ages of 343 ± 5 Ma and 332 ± 3 Ma. Zircons from the boudin neck pegmatites record a prolonged growth history, marked by fluid influx, during amphibolite facies metamorphism beginning at c . 375 Ma. The cross-cutting pegmatites show that dextral deformation in the gneisses and ductile mylonite zones had stopped by c . 340 Ma. Ultrahigh-pressure metamorphism in the eastern block at 360 Ma requires that the Greenland Caledonides were in an overall contractional plate tectonic regime. This, combined with 20% steep amphibolite facies lineations in the eclogites, gneisses and mylonites suggests that dextral transpression may have been responsible for a first stage of eclogite exhumation between ... Article in Journal/Newspaper Danmarkshavn East Greenland Germania land Greenland Cambridge University Press Geological Magazine 143 4 431 446 |
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English |
description |
The North-East Greenland eclogite province is divided into a western, central and eastern block by the sinistral Storstrømmen shear zone in the west and the dextral Germania Land deformation zone in the east. A family of steep, NNW-striking dextral mylonite zones in the Danmarkshavn area are geometrically and kinematically similar to the ductile Germania Land deformation zone, located 25 km to the east. Amphibolite facies deformation at Danmarkshavn is characterized by boudinage of eclogite bodies within quartzofeldspathic host gneisses, pegmatite emplacement into the boudin necks and subsequent deformation of pegmatites parallel to gneissosity, a widespread component of dextral shear within the gneisses, and localization of strain into 10–50 m thick dextral mylonite zones. The gneisses and concordant mylonite zones are cut by a swarm of weakly to undeformed, steeply dipping, E–W-striking pegmatitic dykes. Oscillatory-zoned zircon cores from two boudin neck pegmatites give weighted mean 206 Pb/ 238 U sensitive, high mass resolution ion microprobe (SHRIMP) ages of 376 ± 5 Ma and 343 ± 7 Ma. Cathodoluminescence images of these zircons reveal complex additional rims, with ages from ranging from c . 360 to 320 Ma. Oscillatory-zoned, prismatic zircons from two late, cross-cutting pegmatites yield weighted mean 206 Pb/ 238 U SHRIMP ages of 343 ± 5 Ma and 332 ± 3 Ma. Zircons from the boudin neck pegmatites record a prolonged growth history, marked by fluid influx, during amphibolite facies metamorphism beginning at c . 375 Ma. The cross-cutting pegmatites show that dextral deformation in the gneisses and ductile mylonite zones had stopped by c . 340 Ma. Ultrahigh-pressure metamorphism in the eastern block at 360 Ma requires that the Greenland Caledonides were in an overall contractional plate tectonic regime. This, combined with 20% steep amphibolite facies lineations in the eclogites, gneisses and mylonites suggests that dextral transpression may have been responsible for a first stage of eclogite exhumation between ... |
format |
Article in Journal/Newspaper |
author |
SARTINI-RIDEOUT, C. GILOTTI, J. A. McCLELLAND, W. C. |
spellingShingle |
SARTINI-RIDEOUT, C. GILOTTI, J. A. McCLELLAND, W. C. Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
author_facet |
SARTINI-RIDEOUT, C. GILOTTI, J. A. McCLELLAND, W. C. |
author_sort |
SARTINI-RIDEOUT, C. |
title |
Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
title_short |
Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
title_full |
Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
title_fullStr |
Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
title_full_unstemmed |
Geology and timing of dextral strike-slip shear zones in Danmarkshavn, North-East Greenland Caledonides |
title_sort |
geology and timing of dextral strike-slip shear zones in danmarkshavn, north-east greenland caledonides |
publisher |
Cambridge University Press (CUP) |
publishDate |
2006 |
url |
http://dx.doi.org/10.1017/s0016756806001968 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756806001968 |
genre |
Danmarkshavn East Greenland Germania land Greenland |
genre_facet |
Danmarkshavn East Greenland Germania land Greenland |
op_source |
Geological Magazine volume 143, issue 4, page 431-446 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756806001968 |
container_title |
Geological Magazine |
container_volume |
143 |
container_issue |
4 |
container_start_page |
431 |
op_container_end_page |
446 |
_version_ |
1810440954373472256 |