摘要
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.
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.
基金
supported by the National Natural Science Foundation of China(Grant Nos.40132010 and 40273018).
