The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3.Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by...The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3.Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by microstructures and shortening adjacent to the discrete crenulation cleavage, S2. Microstructures of folded vein segments, their geometric changes and truncation to cleavage (S2) are mainly due to pressure-solution phenomena and the estimated volume loss from reconstructed vein segments range from 16 to 25.5%,which is closely related to volume decrease (26%) calculated from the polydeformed slates of North Wales areas.展开更多
A systematic Sm-Nd isotopic study was carried out for sediments and metasediments of different ages from Mesoproterozoic to early Mesozoic era in southwestern Fu-jian, Eastern Nanling Range. The results show that Nd m...A systematic Sm-Nd isotopic study was carried out for sediments and metasediments of different ages from Mesoproterozoic to early Mesozoic era in southwestern Fu-jian, Eastern Nanling Range. The results show that Nd model age (tDM) and e Nd(t) value of most sediments are closely simi-lar to those of Paleoproterozoic Mayuan Group, indicating that they may mainly be the recycling product of Paleopro-terozoic crustal materials. However, the Nd model age sig-nificantly decreases with a corresponding increase in the e Nd(t) value at Neoproterozoic (ca. 0.8—0.7 Ga) and Late Paleozoic (ca. 0.25 Ga), respectively. This is manifested by prominent vales and apexes on the diagrams of tDM vs. tStr. (stratum age) and e Nd(t) vs. tStr.. The decrease in tDM and the increase in e Nd(t) are explained as a result of the significant incorporation of juvenile crustal materials that originated from depleted mantle due to strong lithospheric extension during both periods. It appears that tectonic magmatism in the Neoproterozoic and the Late Paleozoic is of prominent importance in affecting the geochemical nature of sediments in South China.展开更多
文摘The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3.Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by microstructures and shortening adjacent to the discrete crenulation cleavage, S2. Microstructures of folded vein segments, their geometric changes and truncation to cleavage (S2) are mainly due to pressure-solution phenomena and the estimated volume loss from reconstructed vein segments range from 16 to 25.5%,which is closely related to volume decrease (26%) calculated from the polydeformed slates of North Wales areas.
基金supported by the National Natural Science Foundation of China(Grant Nos.40132010 and 40273018).
文摘A systematic Sm-Nd isotopic study was carried out for sediments and metasediments of different ages from Mesoproterozoic to early Mesozoic era in southwestern Fu-jian, Eastern Nanling Range. The results show that Nd model age (tDM) and e Nd(t) value of most sediments are closely simi-lar to those of Paleoproterozoic Mayuan Group, indicating that they may mainly be the recycling product of Paleopro-terozoic crustal materials. However, the Nd model age sig-nificantly decreases with a corresponding increase in the e Nd(t) value at Neoproterozoic (ca. 0.8—0.7 Ga) and Late Paleozoic (ca. 0.25 Ga), respectively. This is manifested by prominent vales and apexes on the diagrams of tDM vs. tStr. (stratum age) and e Nd(t) vs. tStr.. The decrease in tDM and the increase in e Nd(t) are explained as a result of the significant incorporation of juvenile crustal materials that originated from depleted mantle due to strong lithospheric extension during both periods. It appears that tectonic magmatism in the Neoproterozoic and the Late Paleozoic is of prominent importance in affecting the geochemical nature of sediments in South China.
