黑龙江镜泊湖地区全新世火山岩^(14)C测年及其源区特点探讨  

^(14)C Dating of Holocene Volcanic Rocks of the Jingpohu Region,Heilongjiang Province, and Characteristics of Their Source Regions

作　　者：张招崇[1] 李兆鼐[1] 李树才[2] 辛影[2] 李兆木[2] 王先政[2] 尹金辉[3] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]黑龙江省地质科学研究所,哈尔滨150036 [3]中国地震局地质研究所,北京100029

出　　处：《地质学报》2000年第3期279-286,共8页Acta Geologica Sinica

基　　金：原地质矿产部科技专项"近代火山活动规律;稳定性评价和防灾对策研究"项目

摘　　要：黑龙江镜泊湖地区全新世火山位于镜泊湖西北侧的“火山口森林”和蛤蟆塘两个地区。本次研究分别在“火山口森林”地区的Ⅰ号火山口、Ⅴ号火山口(大干泡)的一、二旋回层和蛤蟆塘地区的Ⅻ号火山口外围的第一旋回层的火山渣中取了3个碳化木进行^(14)C测年,其结果分别为3430±60a、2470±120a、2470±110a和3490±140a(其中Ⅴ号火山口的碳化木进行了两次测试)。根据本区存在3个火山旋回和其他地质特征以及树木的最老年龄推测,该区最后一次火山活动可能在1000～2000a之间,并且两次火山喷发间隔大约在1000a左右,由此证明镜泊湖火山是东北地区最危险的火山之一。另外,由于“火山口森林”地区和蛤模塘地区的玄武质岩石在岩石学、地球化学以及所含的包体特征存在着巨大的差异性,表明该区在3490a BP前地幔存在着强烈的不均一性,其原因可能与地幔柱的三级构造活动有关。Holocene volcanoes of the Jingpohu region, Heilongjiang Province, are situated i Three gagatite samples from the strata of the first and second sub-cycles of Nos. Ⅰ and Ⅴ (Daganpao) craters of the 'Crater Forest' and the first sub-cycle of No. Ⅻ crater of the 'Frog Pool' respectively were used for14C dating. The dating results are 3430±60, 2470±120, 2470±110 and 3490±140 years respectively (the gagatite sample collected from No. Ⅴ crater was measured twice). Based on the existence of three volcanic sub-cycles in the study area, as well as the geological characteristics and the oldest age of the trees in the study area, it is inferred that the last volcanic eruption happened about 2000 years to 1000 years ago. The interval of two eruptions is about 1000 years. It shows that the Jingpohu volcano is one of the most dangerous volcanoes in Northeast China. Great differences in petrological and geochemical characteristics of the basaltic rocks and mantle inclusions between the 'Crater Forest' and the 'Frog Pool' show the extreme heterogeneity of the mantle source beneath the Jingpohu region 3490 years ago. It was probably related to the third -class activity of the mantle plume beneath the area.

关 键 词：全新世 火山岩 源区特点 碳同位素 测年 

分 类 号：P597[天文地球—地球化学]