CAJ | 학술논문

在胶莱盆地南缘开展1∶5万区调工作的基础上，对胶莱盆地南缘的白垩纪青山群火山岩进行了层型剖面实测及系统采样，经过化学分析及数据整理，得出胶莱盆地南缘白垩纪青山群火山岩 SiO2的含量为51．08％～74．86％，全碱（Na2 O＋K2 O）含量的变化范围为3．2％～8．8％，Al2 O3的含量集中于13．18％～17．3％之间，全铁（TFe2 O3）含量的变化范围在0．86％～10．48％之间；火山岩微量元素强烈富集大离子亲石元素 La 和 Nd，亏损高场强元素 Nb、P 和 Ti，轻稀土元素（LREE）相对富集，重稀土元素（HREE）相对亏损。后夼组与石前庄组火山岩的地球化学特征较相似，以酸性火山岩为主，而八亩地组和方戈庄组火山岩的地球化学特征较相似，以中-中偏基性火山岩为主；后期喷发的石前庄组与方戈庄组火山岩较前期的后夼组、八亩地组火山岩碱性物质含量增加。通过综合分析得出，胶莱盆地南缘白垩纪青山群火山岩是一套中-酸性过铝质、富钾钙碱性为主的火山岩，其四个不同喷发期次的岩浆应来源于同一岩浆源---下地壳，可能与扬子板块的俯冲作用有关，岩浆形成演化过程中表现出强烈的结晶分异作用，基于青山群火山岩岩性及岩浆源分析，认为其不属于典型的双峰式火山喷发。
재효래분지남연개전1∶5만구조공작적기출상，대효래분지남연적백성기청산군화산암진행료층형부면실측급계통채양，경과화학분석급수거정리，득출효래분지남연백성기청산군화산암 SiO2적함량위51．08％～74．86％，전감（Na2 O＋K2 O）함량적변화범위위3．2％～8．8％，Al2 O3적함량집중우13．18％～17．3％지간，전철（TFe2 O3）함량적변화범위재0．86％～10．48％지간；화산암미량원소강렬부집대리자친석원소 La 화 Nd，우손고장강원소 Nb、P 화 Ti，경희토원소（LREE）상대부집，중희토원소（HREE）상대우손。후천조여석전장조화산암적지구화학특정교상사，이산성화산암위주，이팔무지조화방과장조화산암적지구화학특정교상사，이중-중편기성화산암위주；후기분발적석전장조여방과장조화산암교전기적후천조、팔무지조화산암감성물질함량증가。통과종합분석득출，효래분지남연백성기청산군화산암시일투중-산성과려질、부갑개감성위주적화산암，기사개불동분발기차적암장응래원우동일암장원---하지각，가능여양자판괴적부충작용유관，암장형성연화과정중표현출강렬적결정분이작용，기우청산군화산암암성급암장원분석，인위기불속우전형적쌍봉식화산분발。
On the basis of the work that the regional geological survey of JiaolaiBasin southern margin was carried,the stratotype section for the volcanic rocks of Cretaceous Qingshan Group in study area was measured with system sampling.It was showed that the content of SiO2 in the volcanic rocks of Cretaceous Qingshan Group is about 51.08%~74.86%,total alkalis (Na2 O+K2 O)is about 3.2%~8.8%,Al2 O3 is about 13.18% ~ 17.3%,and TFe2 O3 is about 0.86% ~ 10.48%,after chemical analysis and data processing.The character of trace and rare earth element is that La and Nd which are LILE and LREE are relatively enriched,while Nb,P and Ti which are HFSE and HREE are relatively loss.Houkuang and Shiqianzhuang Formation have the similar geochemical characteristics that the volcanic rocks are mainly composed of acidic rocks,while Bamudi and Fanggezhuang Formation have the similar geochemical characteristics that the volcanic rocks are mainly composed of intermediate rocks.The volcanic rocks of Bamudi and Fanggezhuang Formation that erupted lately have more total alkalis than that of Houkuang and Shiqianzhuang Formation.The result of comprehensive analysis was that the volcanic rocks of Cretaceous Qingshan Group in Jiaolai Basin southern margin were intermediate-acidic rocks with peraluminous,K-rich and calc-alkaline characteristic.The magma source of the volcanic rocks that erupted in four different episodes was the same-the lower crust,the reason of which may be related with subduction of Yangtze plate.Magma evolution process of the volcanic rocks showed strong crystal fractionation.Combined with the lithological character and magma source analysis,volcanic rocks of Qingshan Group were not typical bimodal volcanic eruption.