Application Of Electron Probe Analyses Of Minerals In Discussing The Relationship Between Ductile Deformation And Metamorphism

1990 ◽  
Vol 48 (2) ◽  
pp. 250-251
Author(s):  
Fan Guochuan ◽  
Sun Zhongshi
Keyword(s):  
Chemical Composition ◽  
Shear Deformation ◽  
Electron Probe ◽  
General Rule ◽  
Granulite Facies ◽  
Ductile Deformation ◽  
Higher Temperature ◽  
Ductile Shear ◽  
The Relationship ◽  
Ductile Shear Deformation

Under influence of ductile shear deformation, granulite facies mineral paragenesis underwent metamorphism and changes in chemical composition. The present paper discusses some changes in chemical composition of garnet in hypers thene_absent felsic gnesiss and of hypersthene in rock in early and late granulite facies undergone increasing ductile shear deformation .In garnet fetsic geniss, band structures were formed because of partial melting and resulted in zoning from massive⟶transitional⟶melanocrate zones in increasing deformed sequence. The electron-probe analyses for garnet in these zones are listed in table 1 . The Table shows that Mno, Cao contents in garnet decrease swiftly from slightly to intensely deformed zones.In slightly and moderately deformed zones, Mgo contents keep unchanged and Feo is slightly lower. In intensely deformed zone, Mgo contents increase, indicating a higher temperature. This is in accord with the general rule that Mgo contents in garnet increase with rising temperature.

40Ar/ 39Ar laser dating of Zongwulong ductile shear zone in northeastern Tibetan Plateau ：Constrains on the closure time of the northmost Paleo-Tethys ocean

2021 ◽  
Author(s):  
Wanli Gao ◽  
Zongxiu Wang
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Ductile Deformation ◽  
Low Grade ◽  
Ductile Shear Zone ◽  
The South ◽  
Oblique Collision ◽  
Ductile Shear ◽  
Tethys Ocean ◽  
Tectonic Belt

<p><strong><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.67d6c7216eff55356050161/sdaolpUECMynit/12UGE&app=m&a=0&c=5572aca4b392eef83f52919e1be673e9&ct=x&pn=gepj.elif&d=1" alt="">Abstract</strong>：The Zongwulong tectonic belt (ZTB) is located between the northern Qaidam tectonic belt and the south Qilian orogenic belt and contains Late Paleozoic and Early- Middle Triassic strata. Structural features and geochronology of Zongwulong ductile shear zone have key implications for the tectonic property of the ZTB. This study integrated field structure, microscopic structure and <sup>40</sup>Ar/<sup>39</sup>Ar laser probe analysis. The shear zone strikes ~NEE-SWW and dips at a high angle, with a NWW-SEE trending and WE stretching lineation, indicating the shear zone as a thrust- slip shear ductile shear. The asymmetric folds, rotating porphyroclast,structural lens and crenulation cleavage can be seen in the field. Mica fish, S − C fabrics, σ type quartz porphyroclastic and quartz wire drawing structure can also be observed under microscope, indicating that the strike- slip- related ductile deformation and mylonitization occurred under low- grade greenschist facies conditions at temperatures of <em>300° C − 400° C</em>.  The highly deformed<br>mylonite schist yielded <sup>40</sup>Ar/<sup>39</sup>Ar ages <em>(245.8±1.7)Ma </em>and <em>(238.5±2.6)</em>Ma for muscovite and biotite, respectively, indicating that the shear deformation occurred during the Early- Mid Triassic. Combined with comprehensive analysis of regional geology and petrology, the authors hold that the age of ductile shear deformation represents the time of Triassic orogeny in the ZTB. The oroginic activity was probably related to the oblique collision between the South Qilian block and the Oulongbuluke block after the closure of the northermost Paleo-Tethys ocean.</p>

Ductile shear deformation and gold mineralization in the Hetai goldfield of the Yunkai Massif, South China Block

2019 ◽  
Vol 54 (2) ◽  
pp. 929-945
Author(s):  
Jinlong Ni ◽  
Junlai Liu ◽  
Jingcao Wang ◽  
Xiaoling Tang ◽  
Zhong Wang ◽  
...  
Keyword(s):  
Shear Deformation ◽  
South China ◽  
Gold Mineralization ◽  
South China Block ◽  
Ductile Shear ◽  
Ductile Shear Deformation

scholarly journals Ductile shear deformation of the Sambagawa metamorphic rocks in the Kanto Mountains.

2001 ◽  
Vol 107 (5) ◽  
pp. 337-353 ◽  
Author(s):  
Tatsumi Abe ◽  
Hideo Takagi ◽  
Koji Shimada ◽  
Shinji Kimura ◽  
Keisuke Ikeyama ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Metamorphic Rocks ◽  
Ductile Shear ◽  
Ductile Shear Deformation

scholarly journals The geology and petrology of the Precambrian rocks to the north-east of the fjord Qagssit, Frederikshåb district, South-West Greenland

1972 ◽  
Vol 103 ◽  
pp. 1-98
Author(s):  
G Rivalenti ◽  
A Rossi
Keyword(s):  
Granulite Facies ◽  
Amphibolite Facies ◽  
Ductile Deformation ◽  
Brittle Deformation ◽  
Metamorphic History ◽  
North East ◽  
The North ◽  
South West ◽  
Five Phases ◽  
The Relationship

The area consists of migmatitic gneisses (with related pegmatites) containing small inclusions and larger concordant layers of unmigmatised rocks (mainly represented by amphibolites, metasediments and ultramafics), and a few discordant amphibolite dykes. The petrography of the various lithotypes is described and their petrogenesis discussed. The following metamorphic history is proposed: 1) an increase in metamorphic grade to the biotite-almandine-cordierite subfacies of the low hornblende-granuIite facies, shown only by a few relic assemblages, followed by 2) retrogression to within the almandine-amphibolite facies. Migmatisation (quartz dioritisation or granodioritisation) started in the low hornblende-granulite facies and reached its maximum in the upper almandine-amphiboIite facies. A general microcline blastesis and formation of microcline-rich mobilisates is ascribed to the medium to low almandine-amphibolite facies. Further retrogression to epidoteamphiboIite or greenschist facies is only local and weak. Several generations of post-orogenic basic dykes intersect the gneisses. Structurally, five phases of ductile deformation and three phases of brittle deformation are distinguished, and the relationship between deformation and metamorphism tentatively established. The metamorphic and structural events are mostly pre-Ketilidian.

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