西准噶尔海山俯冲的地质效应:来自泥盆纪—石炭纪火山岩地球化学证据
发布时间：2018-12-27 21:12
【摘要】：海山或火山岛链俯冲与洋壳俯冲具有明显不同的动力学和岩浆效应,主要表现在俯冲带的地貌、发生地震的频度和烈度及火山弧岩浆作用和资源效应。西准噶尔地区泥盆纪—石炭纪火山岩分布有限,多以夹层产出,岩性主要为玄武岩和安山岩,地球化学特征显示:钙碱性和碱性系列均有发育,具有E-MORB或OIB特征,较高的Nd/Sm及~(206)Pb/~(204)Pb比值,明显亏损Nb、Ta、Ti,具有岛弧岩浆特点。结合西准噶尔蛇绿混杂岩中不断识别出OIB特征玄武岩并认为其形成于大洋板内海山的地质事实,提出泥盆纪—石炭纪火山岩具有E-MORB和OIB特征很可能是受早期形成海山在俯冲带内部部分熔融的影响,即为海山俯冲的地质效应,而这种海山俯冲的地质效应可能在整个古亚洲洋的演化过程中都存在,然而需要后续进一步工作。海山俯冲模式的提出不仅丰富了西准噶尔火山岩成因理论,而且为研究西准噶尔构造岩浆事件提供了新思路。
[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.
【作者单位】： 长安大学地球科学与资源学院;国土资源部岩浆作用成矿与找矿重点实验室;
【基金】：国家自然科学基金项目(41303027) 陕西省青年科技新星计划项目(2016KJXX-71) 中央高校基本科研业务费专项资金项目(310827153506,310827153407)
【分类号】：P534.4;P588.14
，
本文编号：2393609
[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.
【作者单位】： 长安大学地球科学与资源学院;国土资源部岩浆作用成矿与找矿重点实验室;
【基金】：国家自然科学基金项目(41303027) 陕西省青年科技新星计划项目(2016KJXX-71) 中央高校基本科研业务费专项资金项目(310827153506,310827153407)
【分类号】：P534.4;P588.14
，
本文编号：2393609
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