Discrimination criteria of Dupal anomaly based on cluster analysis and its application in the Indian Ocean
The Dupal anomaly is a large-scale mantle geochemical heterogeneity idly distributed in the southern hemisphere.Its distribution range and origin have always been the focus of geological research.As the first proposal of the Dupal anomaly was only based on very limited rock samples,its concept has long been ambiguous and uncertain.No unified discriminant index of anomaly has been reconciled,which affects the understanding of the anomaly distribution range and origin,and thus restricts the further study of the global Dupal anomaly.This paper assembled the lead isotopic data of basalts from the Indian Ocean(including the axis of mid-ocean ridges and off-axis regions),using the K-means++clustering analysis method to highlight large-scale geochemical characteristics.Combined with the well-known geochemical boundaries of the Southwest Indian Ridge and the Southeast Indian Ridge,the criteria for the Dupal anomaly could be defined as Δ7/4＞2.5 and Δ8/4＞35.Based on this criterion,the Owen fracture zone was recognized as the Dupal anomaly boundary for the Northwest Indian Ridge,with the south region of the boundary showing a more obvious Dupal anomaly.The Dupal anomaly region of the entire Indian Ocean mid-ocean ridges is located in the area bounded by the Andrew-Bain fracture zone,the Australia Antarctic Discordance and the Owen fracture zone.Off-axis regions,such as the Kerguelen Plateau,Broken Ridge,Ninetyeast Ridge,Christmas Islands,Mozambique Plateau,Agulhas Plateau,etc.,also exhibit strong Dupal anomalies.The Dupal anomaly distribution of the whole Indian Ocean shows linear gradient characteristics from west to east.The discrimination criteria of Dupal anomaly identified based on the Indian Ocean basalt will provide a reference for the global Dupal anomaly investigation.The delineation of the distribution range of the Indian Ocean Dupal anomaly will provide a key basis for revealing its origin.
Indian OceanDupal anomalyClustering analysisPb isotopesGeochemistry
万方数据
维普
