龙岗金垅顶子近代活动火山的岩石学与地球化学

距今１６００ 年前喷发的金龙顶子火山是龙岗火山群中一座最年轻的近代活动火山, 它的喷发物包括金龙顶子火山锥体 （海拔９９９．４ｍ ）、熔岩流及其广布的火山碎屑席 （四海火山渣层）。金龙顶子火山岩为单一的粗面玄武岩, 有着极为相似的ＲＥＥ和不相容元素分布模式, ８７Ｓｒ／８６Ｓｒ和１４３Ｎｄ／１４４Ｎｄ 分别变化于０．７０４８４６～０．７０４９２１ 和０．５１２６１９～０．０．５１２６４６, 这反映了它们直接来自地幔源区, 岩浆上升过程极少演化和壳源混染, 具有较为原始的岩浆特点。年轻火山岩中的幔源捕虏体提供了该区存在相对低温 （～９００℃） 含水的地幔。     

2017年全球活动火山时空分布以及阿贡火山喷发前后的形变特征

归纳总结2017年度全球81座活火山的活动情况,共计活动1058座次,平均每周记录20座活火山的活动信息。根据火山潜在喷发的危险性和火山活动的强弱程度对上述火山进行分级描述,火山活动主要反映了地球表层的构造活动,其中大角度俯冲带的弧后火山最为强烈,小角度的俯冲带、拉张裂谷和走滑为主的板块边界火山活动较为平静,火山活动频繁的印度尼西亚岛链是受灾最为严重的区域。预计全球火山活动将进一步加剧,印尼岛链受火山灾害威胁的程度依然较大。位于印尼岛链巴厘岛上的阿贡火山自2017年9月开始活动以来,整个喷发过程极具代表性,监测阿贡火山喷发过程可为全球典型火山喷发事件研究提供参考。     

中国东部全新世火山的镭-钍同位素年代学

活火山是指1万年来有过喷发历史的全新世火山。火山的高分辨年代学对火山灾害评估和火山分类具有重要意义。对于缺乏历史记载的全新世火山,直接对火山岩进行同位素定年很困难。本文利用具有高时间分辨率的镭-钍-铀非平衡确定中国东部年轻火山的年龄。根据镭-钍-铀同位素,海南岛的马鞍岭和雷虎岭是全新世火山(马鞍岭:4.3ka;雷虎岭:4.7ka);镜泊湖火山(4.9ka)也是全新世火山;龙岗火山存在晚更新世和全新世活动(7.0ka,15.0ka);大兴安岭阿尔山和诺敏河Ra/Th非平衡消失但~(230)Th/~(238)U非平衡显著,属于晚更新世喷发(阿尔山:63ka;诺敏河:71ka)。海南岛的马鞍岭火山、雷虎岭火山和东北地区的龙岗火山、镜泊湖火山,是4座活火山。至于东北地区的阿尔山和诺敏河火山是否是活火山,有待测试更多样品的Ra/Th同位素。五大连池老黑山和火烧山有历史喷发记录,这与它们都存在显著Ra/Th非平衡一致。五大连池老黑山和火烧山的岩浆滞留年龄分别小于4.2ka和3.2ka,岩浆上升速率 18～23m/y。     

中国大陆几个活火山深部细结构及深部起源

中国大陆有很多火山,如五大连池火山、长白山火山、腾冲火山、海南火山、大同火山和昆仑山火山等,其中五大连池火山、长白山火山和腾冲火山被认为是活火山(刘嘉麒,1999;刘若新,2000).人们对这些火山区已开展了大量研究工作,但深部起源问题还一直不太清楚.     

中国活火山研究

本文对中国已发现的长白山天池火山、金龙顶子火山、镜泊湖全新世火山群、五大连池热田区具备发生新的喷发的基本条件作了讨论。指出中国仍存在火山灾害威胁。必须一方面加强对活火山的监测和研究;另一方面加强对火山区特有的火山景观和地热等资源的开发利用。     

天堂里的绝色美人——瓦努阿图

<正>蹦极这项风靡世界的运动原来起源于这里。岛上的传统沙画不仅是历史悠久的艺术表现形式,对于群岛的中心和北方诸岛的岛民来说,那还是一种通讯手段。在这里,被国人视为"极品"的梅花参到处都是,它们粗壮的身形,在国内是极少能看到的。这里是瓦努阿图。     

Application of hot spring gases to the study of active volcanoes in the Changbaishan Mountain region,Northeast China

The authors reviewed the history of geochemistry involved in active volcano monitoring and analyzed the relationship between variations in volcanic gas composition observed at the Changbaishan Volcano Observatory and volcanic activities. It is concluded that both geochemical method and routine gas analysis can provide the information about volcanic activity and earthquake activity, and both of them can play an important role in predicting volcano eruption.     

ON TECTONIC PROBLEMS OF THE OKINAWA TROUGH

The Okinawa Trough is a very active tectonic zone at the margin of the Northwest Pacific and is typical of back-arc rifting at the young stage of tectonic evolution. Many scientists from Japan,China, Germany, France, the U. S.A. and Russia have done a lot of geologic and geophysical investigations there. It is well known that the Okinawa Trough is an active back-arc rift with extremely high heat flow, very strong hydrothermal circulation, strong volcanic and magmatic activity, frequent earthquakes,rapid subsidence and rifting, well-developed fault and central graben. But up to now, there are still some important tectonic problems about the Okinawa Trough that require clarification on some aspects such as the type of its crust, its forming time, its tectonic evolution, the distribution of its central grabens, the relationship between its high heat flow and tectonic activity. Based on the data obtained from seismic sur-vey, geomagnetic and gravity measurements, submarine sampling and heat flow measurements in the last 15 years, the author discusses the following tectonic problems about the Okinawa Trough: (1) If the Okinawa Trough develops oceanic crust or not. (2) Is the South Okinawa Trough tectonically more active than the North Okinawa Trough with shallower water and few investigation data on it. (3) The formation time of the Okinawa Trough and its tectonic evolution. The Okinawa Trough has a very thin continental crust. Up to now, there is no evidence of oceanic crust in the Okinawa Trough. The North, Middle and South Okinawa Trough are all very strongly active areas. From 6 Ma B.P. , the Okinawa Trough began to form. Since 2 Ma, the Okinawa Trough has been very active.     

洋底的地球物理学研究

在参加国际“Inter Margins”计划的匡架内,美国学者在2004年夏季详细研究了位于马利亚纳岛弧西北岸边的罗塔海底活火山。太平洋的这个海区不仅因为该区海底发生着强烈的气体、气液和熔岩喷发,并且以其对研究裂谷生成过程的重要性而具有重要意义。纽约州哥伦比亚大学拉蒙物·多