Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins

Gautier Nicoli,  Brendan Dyck

Gautier Nicoli,  Brendan Dyck. Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins[J]. 地学前缘, 2018, 9(4): 967-975. DOI: 10.1016/j.gsf.2017.12.009
引用本文: Gautier Nicoli,  Brendan Dyck. Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins[J]. 地学前缘, 2018, 9(4): 967-975. DOI: 10.1016/j.gsf.2017.12.009
Gautier Nicoli,  Brendan Dyck. Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins[J]. Geoscience Frontiers, 2018, 9(4): 967-975. DOI: 10.1016/j.gsf.2017.12.009
Citation: Gautier Nicoli,  Brendan Dyck. Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins[J]. Geoscience Frontiers, 2018, 9(4): 967-975. DOI: 10.1016/j.gsf.2017.12.009

Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins

基金项目: 

The authors thank Richard Palin and Christopher J. Spencer, for their invitation to join this special issue. Victor Guevara and an anonymous reviewer are thanked for providing useful comments that improved this study.

详细信息
    通讯作者:

    Gautier Nicoli,E-mail:ng422@cam.ac.uk

Exploring the metamorphic consequences of secular change in the siliciclastic compositions of continental margins

Funds: 

The authors thank Richard Palin and Christopher J. Spencer, for their invitation to join this special issue. Victor Guevara and an anonymous reviewer are thanked for providing useful comments that improved this study.

  • 摘要: Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth's continental margins, past and present. This study explores the metamorphic consequence of these compositional changes, by comparing phase equilibrium models constructed for average Archean, Proterozoic, and Phanerozoic shale and greywacke compositions equilibrated along two Barrovian-type geotherms: 1330 °C/GPa (A) and 800 °C/GPa (B). Our models show that Archean siliciclastic rocks can retain up to 4 vol.% water at middle to lower crustal conditions, nearly twice that of Proterozoic and Phanerozoic compositions. The increased ferromagnesium content of Archean siliciclastic rocks stabilizes chlorite to higher temperatures and results in a biotite-rich assemblage at solidus temperatures. Accordingly, water-absent biotite dehydration melting is predicted to play a greater role in the generation of melt in the metamorphism of Archean aged units, and water-absent muscovite dehydration melting is of increasing importance through the Proterozoic and Phanerozoic. This secular variation in predicted mineral assemblages demonstrates the care with which metamorphic facies diagrams should be applied to Archean compositions. Moreover, secular changes in the composition of shale and greywacke is reflected in the evolution of anatectic melt towards an increasingly less viscous, Ca-rich, and Mg-poor monzogranite.
    Abstract: Shale and greywacke compositions from the Archean to Phanerozoic record a secular change in the siliciclastic material that comprises much of Earth's continental margins, past and present. This study explores the metamorphic consequence of these compositional changes, by comparing phase equilibrium models constructed for average Archean, Proterozoic, and Phanerozoic shale and greywacke compositions equilibrated along two Barrovian-type geotherms: 1330 °C/GPa (A) and 800 °C/GPa (B). Our models show that Archean siliciclastic rocks can retain up to 4 vol.% water at middle to lower crustal conditions, nearly twice that of Proterozoic and Phanerozoic compositions. The increased ferromagnesium content of Archean siliciclastic rocks stabilizes chlorite to higher temperatures and results in a biotite-rich assemblage at solidus temperatures. Accordingly, water-absent biotite dehydration melting is predicted to play a greater role in the generation of melt in the metamorphism of Archean aged units, and water-absent muscovite dehydration melting is of increasing importance through the Proterozoic and Phanerozoic. This secular variation in predicted mineral assemblages demonstrates the care with which metamorphic facies diagrams should be applied to Archean compositions. Moreover, secular changes in the composition of shale and greywacke is reflected in the evolution of anatectic melt towards an increasingly less viscous, Ca-rich, and Mg-poor monzogranite.
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出版历程
  • 收稿日期:  2017-06-30
  • 修回日期:  2017-11-10
  • 录用日期:  2017-12-05
  • 网络出版日期:  2023-05-31
  • 发布日期:  2018-06-30

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