火山活动与构造气候旋回

火山活动是一种重要的地质现象,它的发生总是与构造运动相关联,构造运动有强有弱,持续时间有长有短,具有旋目性,火山活动同样也具有旋回性。大规模的火山喷发往往会对气候变化产生影响,而影响的程度取决于火山所处的位置和喷发的性质及程度。强烈的火山喷发将造成局部地区乃至全球气温下降,由此人们推测火山喷发多发生在冰期,然而统计资料表明,绝大多数火山喷发发生在间冰期,此时的构造运动也比较活跃,而在冰期时很少有火山喷发。至于火山喷发后在短时间内造成的降温与长时间的冰期不能相提并论。火山活动有旋回性,它影响的气候变化也具备有旋回性,这是构造气候旋回的一种表现形式。

VOLCANIC ACTIVITIES AND TECTONIC-CLIMATIC CYCLES

Volcanic activities are always accompanied with a large scale of tectonic activities .The most explosive periods are almost consistent with most active periods of tectonicmovements. Meantime the tectonic-volcanic activities are related to a large areal orglobal climatic changes.After collision between india and Eurasia Plates, occurred during about in 45-10MaB. P., there were a large volume of intermediate-acidic rocks in Gangdisi,southern Tibet during the same period. The another upsurge of volcenic activities generated during about 37 35MaB.P. There are a large volume of volcanic rocks inTibetan Plateau and eastern continental rift are4 respectively , correlating with a largescale of tectonic movement in 37- 35MaB.P. It is not only style change of volcanicactivities at 0.73MaB. P. but also rapidly climatic change occurring at 0.8MaB. P.Volcanic activities stabed at 0.73MaB. P. in many areas, such as Ashikelo volcanic eruption and Datong volcanic eruptions etc. which started to enter the upsurges ofvolcanic activities , and about meantime several other volcanic eruptions were nearceased .In thes paper, the volcanic activities of QUaternary in China were correlated withglacial period / interglacial periods based on the data of volcaic rock ages. Theupsurges of volcanic activities of Quaternary in China including both Tibet andEastern continental rift system occurred during 1.50- 1.10MIB. p., 0.73- 0.20MaB. P.,0.12- 0.07MaB. P. and 0.01 - 0MaB. P. respectively . They were mainly correlated withthe four interglacial periods, respectively . In Quaternary , most of volcanic eruptionsgenerated during interglacial periods in China.1.50- 1.10MaB. P. belongs to Longgang volcanic astivity episode which is thefirst upsurge of volcanic eruptions in Quaternary in China, forming volcanic rocks distributed in Xiaoyizishan Mountain, Longgang, Jiashan, Anhui Province. BaitoushanMountain volcanic activity episode that duration is 0.73- 0.20MaB.P. correlated withanother inter-glacial Period too. Those volcanic rocks formed during mis episode aremainly distributed in both continental rift system of northeastern China, northern Chinaand continental margin of southeastern China and northern Tibetan Plateau.Jinlongdingzi volcanic activity episode occurred during the episode 0.12- 0.07MaB.P.,which correlated also with the last interglacial Period. The volcnic rocks related withthes episode are mainly limited in the regions of Jinlongdingzi area of Longgang Quaternary volcanic field, Changbaishan Mountain, Leiqiong, and Tibetan Plateau.Holocene Wudalianchi volcanic episode consists mainly of all of the active volcanoesin China, for example Tengchong, Changbaishan Mountain, Wudalianchi, Longgang volcanic field, and some of northern Tibetan Plateau.A large amount of stratospheric aerosols provided by volcanic eruptions coulddramatically attenuate and decrease the direct solar beam, meantime , a concomitant increase in down-ward-scattered radiation finally causes relatively small decline in totalsolar radiation . This is reason why large explosively volcanic eruptions could declinethe surface temperatUre about lasting two to three years after volcanic eruptions.bee explosively volcanic eruptions could increase precipitation because volcanic aerosols ejecting into stratosphere might act as cloud condensation in stratosphere andvolcanic eruptions could suPPly a large amount of warer into stratosphere . Volcanic erUPtions might influence in surface pressure through changing the temperature of bothstratosphere and troposphere.