琼北马鞍岭地区第四纪火山活动期次划分

DIVISION OF THE ACTIVE PERIOD OF QUATERNARY VOLCANISM IN MAANLING, NORTHERN HAINAN PROVINCE

琼北马鞍岭地区第四纪火山活动具有多期性。据火山作用方式、火山形貌及风化程度、火山喷发产物与沉积地层以及火山机构之间的相互叠置关系 ,结合同位素年龄 ,可分为德义岭、道堂、杨花、雷虎岭、昌道和马鞍岭等 6期 ,其中德义岭期为中更新世 ,道堂和杨花期为晚更新世 ,雷虎岭、昌道和马鞍岭期属全新世。不同期次具有不同的火山活动方式、喷发强度及火山结构类型。德义岭期火山活动以溢流为主 ,火山锥为低缓的熔岩穹丘。杨花期为射气岩浆爆发作用形成的低平火山。雷虎岭与马鞍岭期主要形成由碎屑锥和熔岩流组成的夏威夷式火山 。

The Quaternary volcanism in Ma'anling area, northern Hainan Province is characterized by multi-periodic activity. Based on several factors, such as the active manner of the volcano, volcanic morphology, weathering degree, volcanic eruptive cumulus deposition, sedimentary stratigraphy, mutual superimposition relation between the volcanic apparatus, and isotope age, the Quaternary volcanic activity in Ma'anling area can be divided into Deyiling stage of mid-Pleistocene age, Daotang and Yanghua stages of late Pleistocene age, Leihuling, Changdao and Maanling stages of Holocene age. Different stages have different volcanic regimes, eruptive intensity and volcanic structural type. Volcanic activity at Deyiling stage was dominated mainly by overflowing, and the resulted volcanic cone is lava dome. The Daotang stage was characterized by relatively great intensity and obvious active phases. The volcano of this stage consists of planar lava flow and pyroclastic cone. The Yanghua stage was dominated by phreatomagmatic explosion that resulted in maar. Volcanism at Leihuling and Maanling stages resulted in Hawaiian-type volcano, which consists mainly of pyroclastic cone and pahoehoe lava.