摘要
巴马县水晶宫洞内次生化学沉积物景观丰富,类型多样,有石钟乳、石幔、石瀑布、石笋、石柱、石盾等特色景观;尤其是近期仍在发育的洞顶鹅管、卷曲石、石花等是国内外较为罕见的洞穴奇景.据沉积物的沉积类型、物质成分、沉积序次及测年等资料研究表明,水晶宫洞穴沉积物形成于晚第三纪以来.晚第三纪和第四纪早更新世早期,洞内沉积主要为外源水携带的硅质岩、砂岩类砾石沉积形成的钙华砾石层.早更新世中期一中更新世气候温暖湿润,是水晶宫洞穴主要景观的形成期,沉积物景观宏大而壮观,230Th-U系测年得出其分别形成于100～35万年前.晚更新世早期1 2.5～9万年的末次间冰期主要为温暖气候环境,洞内仅有少量的石笋沉积,且极少保存；9万年后气候环境发生突变,更不利沉积物发育和保存；自4万年后气候环境开始表现为温暖湿润,化学沉积活跃,洞穴沉积物主要由高约50～150 cm的纯白色石笋群和钟乳石组成,为洞穴奇景的形成期,230Th-U系测年得出其分别形成于40 ka BP和7 500a BP以及1450a BP.晚更新世晚期以来形成的洞穴沉积物景观,不仅为水晶宫提供了丰富的旅游资源和价值,同时也为广西重建古气候环境提供了重要的信息载体.
The Shuijinggong cave is located in Niudongtun,Daluo Village at the northwest Bama County,Guangxi,44 km away from the county （24° 18＇12.3 ＂ N and 107° 00＇41.2＂ E）.It is subtropical monsoon climate with an average annual temperature of 20.4 ℃,annual rainfall of 1 560 mm.The major stratum is the Maokou formation （P1m） of the Lower Permian system,and its lithology is light-colored or gray white,middle-thick-layered or thick-bedded limestone.The next stratum is the Middle Triassic system （T2）,and its lithology is dark gray or gray black of thin mudstone,tuff and siltstone.The Shuijinggong cave is formed in Maokou formation （P1m） of the Lower Permian system,the cave is developed along the bedded structure of limestone and near NS trending fault.The height of the cave entrance is 650 m above sea level and the covering layer on the top of cave is about 100 m to 200 m thick.The total length of cave measures 800 m,the width of cave is 4-40 m,and the height of cave tunnel is 1.5-35 m.Cave temperature is 18.5 ℃ to 19.6 ℃,humidity 95 ％.This condition is suitable for the formation of the cave sediments and landscape protection.The Shuijinggong cave is a newly developed cave with good enclosed conditions and better humidity,there is still a large number of recent carbonate sediments developing in the cave.The landscapes of secondary chemical sediment in the cave is very rich including stalactite,stone curtain,stone waterfall,stalagmites,stone column and stone shield and so on.Furthermore,there are the rarest landscapes of cave sediments at home and abroad,such as the soda straw,helictite and cave flower,which are still growing nowadays on the top of cave.The research also aims to make clear the environmental significance of carbon and oxygen isotope records from sedimentary of modern speleothems.The research results have shown that cave sediments in the Shuijinggong cave began to deposit in the late Tertiary period according to sediment character,composition,sedimentary sequence dating,and its sedimentary was mainly travertine gravel.The main formation period of cave landscapes in the Shuijinggong cave with magnificence and grand landscape characters is the Early Pleistocene and the Middle Pleistocene periods.These speleothems in the Shuijinggong cave,determined by 230Th-U dating age,are formed 1 000 ka BP,520-600 ka BP and 350-400 ka BP,respectively.Climate at the early stage of the Late Pleistocene or the last interglacial period during 125-90 ka BP mainly is warm and humid,and only a small number of stalagmites in cave formed and rarely saved.The sudden change of climatic environment occurred after 90 ka BP is more unsuitable for sediment formation and preservation in cave.The present speleothems,composed of 50-150 cm high,pure white stalagmites and stalactites with exquisitely carved,sculpt fancy,rare cave landscapes,are mainly formed 40 ka BP,7 500 a BP and 1 450 a BP respectively,according to 230Th-U dating.The cave sediment landscapes formed since the late stages of the late Pleistocene do not only provide abundant tourism resources and value for the Shuijingong cave,but also provides important information for paleo-climate reconstruction in Guangxi.
出处
《中国岩溶》
CAS
CSCD
2013年第3期345-357,共13页
Carsologica Sinica
基金
国家自然科学基金(批准号40772216和40802042)
地调局“中国气候变化洞穴沉积记录研究”(编号:12120113005700)
关键词
水晶宫洞穴
沉积物景观
沉积环境
形成时期
广西巴马县
Shuijinggong cave in Bama
landscape of the cave deposit
depositional environment
forming time
Bama County, Guangxi
