Susceptibility, Geochemical Characteristics and Tectonic Significance of Volcanics of North Yellow Sea Basin from Pre-Mesozoic to Mesozoic
Xu Zhongjie
Wang Liaoliang
Kong Yuan
Cheng Rihui
Abstract：The multiple Mesozoic and Mesozoic igneous rocks in the well drilling in the North Yellow Sea basin corffirm the multi-stage tectonic activity experienced by the Mesozoic has been accompanied by the development of multi-stage igneous rocks.A petrology study is carried out on magnetic susceptibility,density,main elements,ICP-MS trace elements and rare earth elements of the volcanics of X1 and X2 well of North Yellow Sea basin in this paper.Results show that tephrite and trachy basalt of Pre-Mesozoic in X1 well of North Yellow Sea basin is weaker magnetic ((131.5-138.5)(4π × 10-6).Dacite in the lower part of X2 and dacite containing breccia in the upper part is weak magnetic ((27.5-82.5)(4π× 10-6)) and rocks of medium density.The tephrite of X1 belongs to the high potassium calcalkaline series and the trachy basalt is the calcalkaline series.These two kinds of volcanics are characterized by higher ΣREE (108.11×10-6 to 208.02×10-6),enriched LREE (LREE/HREE=4.04-6.91) and weak anomalies with δEu (0.99-1.18).And the two layers of volcanic in X2 are both characterized by lower ΣREE,enriched LREE and weak anomalies with δEu.The rare elements are characterized by enriched Ba,U and Sr and depleted Nb and Ta.The ratios of (Rb/Sr)N,(La/Nb)N and (Ba/Nb)N are all higher than those of the original mantle,which indicates that the magma derived from the crust melting.It is concluded that the volcanics of North Yellow Sea basin in Pre-Mesozoic formed in the plate tectonic setting the ones in Mesozoic probably formed in the back-arc extension of plate subduction.
Keywords：North Yellow SeaPre-MesozoicMesozoicvolcanicssusceptibilitytectonic settinggeochemistry
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：16( 191-206 )