The Laochang polymetallic ore deposit at Lancang is one of the well known ancient ore deposits associated with volcanic rocks in the Sanjiang (Tri-river) region of Southwest China. Volcanic rocks are dominated by alka...The Laochang polymetallic ore deposit at Lancang is one of the well known ancient ore deposits associated with volcanic rocks in the Sanjiang (Tri-river) region of Southwest China. Volcanic rocks are dominated by alkali basalt and trachyte basalt. There has long been a controversy on the environment of formation of basalts. Some scholars hold that the basalts were formed in a continental environment, some thought they were formed in an oceanic environment and others considered that the basalts were emplaced in a back-arc basin. This study focuses on the geochemical characteristics of the basalts on the basis of their major elements, REEs and trace elements. At the same time, strongly incompatible elements such as Ta, Th and Hf and their ratios were used to differentiate the geotectonic settings of basalts. The results showed that the basalts in the region studied were formed in a continental rift environment.展开更多
In terms of major element, trace element and REE geochemical characteristics of volcanic rocks in the area studied and by making use of the TiO\-2\|K\-2O\|P\-2O\-5, Th\|Hf\|Ta and Zr\|Nb\|Y trianglar diagrams and the ...In terms of major element, trace element and REE geochemical characteristics of volcanic rocks in the area studied and by making use of the TiO\-2\|K\-2O\|P\-2O\-5, Th\|Hf\|Ta and Zr\|Nb\|Y trianglar diagrams and the environmental discrimination diagrams of incompatible element distribution patterns, the authors have drawn some conclusions that are different from those by previous workers. It is concluded that volcanic rocks in the Laochang Ag polymetallic deposit at Lancang, Yunnan belong to continental within\|plate alkali basalts, and that their geotectonic setting seems to be at the northeastern margin of East Gondwana Land.展开更多
基金Cooperative project between provincial academy and provincial universities of Yunnan Province (2003ADBEA34A025).
文摘The Laochang polymetallic ore deposit at Lancang is one of the well known ancient ore deposits associated with volcanic rocks in the Sanjiang (Tri-river) region of Southwest China. Volcanic rocks are dominated by alkali basalt and trachyte basalt. There has long been a controversy on the environment of formation of basalts. Some scholars hold that the basalts were formed in a continental environment, some thought they were formed in an oceanic environment and others considered that the basalts were emplaced in a back-arc basin. This study focuses on the geochemical characteristics of the basalts on the basis of their major elements, REEs and trace elements. At the same time, strongly incompatible elements such as Ta, Th and Hf and their ratios were used to differentiate the geotectonic settings of basalts. The results showed that the basalts in the region studied were formed in a continental rift environment.
基金ThisresearchprojectwasfinanciallysupportedjointlybytheNationalNaturalScienceFoundationofChina (No .96 914 0 3)andtheImportantProjectsundertheKnowledge InnovationProgramsponsoredbytheChineseAcademyofSciences (No.KZCX2 SW 117)
文摘In terms of major element, trace element and REE geochemical characteristics of volcanic rocks in the area studied and by making use of the TiO\-2\|K\-2O\|P\-2O\-5, Th\|Hf\|Ta and Zr\|Nb\|Y trianglar diagrams and the environmental discrimination diagrams of incompatible element distribution patterns, the authors have drawn some conclusions that are different from those by previous workers. It is concluded that volcanic rocks in the Laochang Ag polymetallic deposit at Lancang, Yunnan belong to continental within\|plate alkali basalts, and that their geotectonic setting seems to be at the northeastern margin of East Gondwana Land.
