The major elements, trace elements. K-Ar age and Sr-Nd-Pb isotopie systems ofthe Cenozoic volcanic rocks in Daheishan Island and Cishan, Penglai, Shandong Province aremeasured. The volcanic rocks ( olivine-nephelinite...The major elements, trace elements. K-Ar age and Sr-Nd-Pb isotopie systems ofthe Cenozoic volcanic rocks in Daheishan Island and Cishan, Penglai, Shandong Province aremeasured. The volcanic rocks ( olivine-nephelinite and nephcline-basanite ) in Daheishan Islanderupted periodically in an interval of 0.32 Ma, from 8.72 Ma. 8.39 Ma. 8.08 Ma to 7.73 Ma. Thevolcanic rocks arc all rich in light REEs. They are similar to the OIB-type alkali basalt in thetrace elements normalized model by primordial mantle: rich in high field elements such as Nb and Ta,and imcompatible elements such as Cs. Rb, Ba, Th. U. The volcanic rocks show a depletion of K andRb elements. It is suggested by the trace elements that the olivine-nephelinite in Daheishan Islandis originated from deep resources under the continental mantle. ε Nd (0) values of the volcanicrocks in Daheishan Island and Cishan are 5.31～8.51 and 7.33 respectively, suggesting that thevolcanic rocks are from the depleted mantle resources, which have higher Sm/Nd ratios than the CHUR.^(143)Nd /^(144)Nd ratios ot Daheishan Island olivine-nephelinite and Cishan alkali basalts are0.512 910～0.513 074 and 0.513 014 respectively. The ^(87)Sr /^(86)Sr of Daheishan Island volcanicrocks are lower than that of Cishan, 0.703 427 ～0.703 482 and 0.703 895 respectively. The DaheishanIsland olivine-nephelinite has the Pb isotopie values as follows: ^(206)Pb/^(204)Pb= 18.028 9～17.972 8. ^(207)Pb / ^(204)Pb = 15.435 8 ～15.402 2 and ^(208)Pb /^(204)Pb = 38.087 6～37.997 5.lower than those of Cishan basanite. The Cishan basanite has ^(206)Pb/^(204)Pb= 18.240 1. ^(207)Pb/^(204)Pb= 15.564 5 and ^(208)Pb /^(204)Pb = 38.535. The authors suggest that theolivine-nephelinite in Daheishan Island is similar to the E-type MORB or Hawaii OIB, and the alkalibasalts in Cishan similar to the Kerguelen OIB. The dominant mantle components of DM+PREMA andperhaps DM ( Dupal type ) are the dominant mantle components for volcanic rocks in Daheishan Islandand Cishan. The PREMA component plays an important role.展开更多
基金supported by the National Major Fundamental Research and Development Project(No.G2000046703).
文摘The major elements, trace elements. K-Ar age and Sr-Nd-Pb isotopie systems ofthe Cenozoic volcanic rocks in Daheishan Island and Cishan, Penglai, Shandong Province aremeasured. The volcanic rocks ( olivine-nephelinite and nephcline-basanite ) in Daheishan Islanderupted periodically in an interval of 0.32 Ma, from 8.72 Ma. 8.39 Ma. 8.08 Ma to 7.73 Ma. Thevolcanic rocks arc all rich in light REEs. They are similar to the OIB-type alkali basalt in thetrace elements normalized model by primordial mantle: rich in high field elements such as Nb and Ta,and imcompatible elements such as Cs. Rb, Ba, Th. U. The volcanic rocks show a depletion of K andRb elements. It is suggested by the trace elements that the olivine-nephelinite in Daheishan Islandis originated from deep resources under the continental mantle. ε Nd (0) values of the volcanicrocks in Daheishan Island and Cishan are 5.31～8.51 and 7.33 respectively, suggesting that thevolcanic rocks are from the depleted mantle resources, which have higher Sm/Nd ratios than the CHUR.^(143)Nd /^(144)Nd ratios ot Daheishan Island olivine-nephelinite and Cishan alkali basalts are0.512 910～0.513 074 and 0.513 014 respectively. The ^(87)Sr /^(86)Sr of Daheishan Island volcanicrocks are lower than that of Cishan, 0.703 427 ～0.703 482 and 0.703 895 respectively. The DaheishanIsland olivine-nephelinite has the Pb isotopie values as follows: ^(206)Pb/^(204)Pb= 18.028 9～17.972 8. ^(207)Pb / ^(204)Pb = 15.435 8 ～15.402 2 and ^(208)Pb /^(204)Pb = 38.087 6～37.997 5.lower than those of Cishan basanite. The Cishan basanite has ^(206)Pb/^(204)Pb= 18.240 1. ^(207)Pb/^(204)Pb= 15.564 5 and ^(208)Pb /^(204)Pb = 38.535. The authors suggest that theolivine-nephelinite in Daheishan Island is similar to the E-type MORB or Hawaii OIB, and the alkalibasalts in Cishan similar to the Kerguelen OIB. The dominant mantle components of DM+PREMA andperhaps DM ( Dupal type ) are the dominant mantle components for volcanic rocks in Daheishan Islandand Cishan. The PREMA component plays an important role.
