【摘要】：海山或火山島鏈俯沖與洋殼俯沖具有明顯不同的動(dòng)力學(xué)和巖漿效應(yīng),主要表現(xiàn)在俯沖帶的地貌、發(fā)生地震的頻度和烈度及火山弧巖漿作用和資源效應(yīng)。西準(zhǔn)噶爾地區(qū)泥盆紀(jì)—石炭紀(jì)火山巖分布有限,多以?shī)A層產(chǎn)出,巖性主要為玄武巖和安山巖,地球化學(xué)特征顯示:鈣堿性和堿性系列均有發(fā)育,具有E-MORB或OIB特征,較高的Nd/Sm及~(206)Pb/~(204)Pb比值,明顯虧損Nb、Ta、Ti,具有島弧巖漿特點(diǎn)。結(jié)合西準(zhǔn)噶爾蛇綠混雜巖中不斷識(shí)別出OIB特征玄武巖并認(rèn)為其形成于大洋板內(nèi)海山的地質(zhì)事實(shí),提出泥盆紀(jì)—石炭紀(jì)火山巖具有E-MORB和OIB特征很可能是受早期形成海山在俯沖帶內(nèi)部部分熔融的影響,即為海山俯沖的地質(zhì)效應(yīng),而這種海山俯沖的地質(zhì)效應(yīng)可能在整個(gè)古亞洲洋的演化過(guò)程中都存在,然而需要后續(xù)進(jìn)一步工作。海山俯沖模式的提出不僅豐富了西準(zhǔn)噶爾火山巖成因理論,而且為研究西準(zhǔn)噶爾構(gòu)造巖漿事件提供了新思路。
[Abstract]:The catenary subduction of seamounts or volcanic islands has distinct dynamics and magmatic effects from oceanic crust subduction, mainly in geomorphology of subduction zone, frequency and intensity of earthquakes, volcanic arc magmatism and resource effect. The Devonian Carboniferous volcanic rocks in the West Junggar area are of limited distribution, mostly interbedded, and their lithology is mainly basalt and andesite. The geochemical characteristics show that both calc-alkaline and alkaline series are developed, with the characteristics of E-MORB or OIB. The higher ratios of Nd/Sm and ~ (206) Pb/~ _ (204) Pb show that the depleted Nb,Ta,Ti, is characterized by island arc magma. Combined with the geological facts that the OIB characteristic basalts have been continuously identified in the western Junggar ophiolite and considered to have been formed in the oceanic intraplate seamounts. It is suggested that the E-MORB and OIB characteristics of Devonian Carboniferous volcanic rocks are probably affected by the partial melting of seamounts in the subduction zone, that is, the geological effects of seamounts subduction. The geological effect of seamounts subduction may exist throughout the evolution of the Paleo-Asian Ocean, but further work is needed. The introduction of the seamount subduction model not only enriches the genetic theory of volcanic rocks in West Junggar, but also provides a new idea for the study of tectonic magma events in West Junggar.
【作者單位】： 長(zhǎng)安大學(xué)地球科學(xué)與資源學(xué)院;國(guó)土資源部巖漿作用成礦與找礦重點(diǎn)實(shí)驗(yàn)室;
【基金】：國(guó)家自然科學(xué)基金項(xiàng)目(41303027) 陜西省青年科技新星計(jì)劃項(xiàng)目(2016KJXX-71) 中央高�；究蒲袠I(yè)務(wù)費(fèi)專項(xiàng)資金項(xiàng)目(310827153506,310827153407)
【分類號(hào)】：P534.4;P588.14
，

本文編號(hào)：2393609