山东半岛黄土堆积中的火山玻璃

VOLCANIC GLASS DISCOVERED IN LOESS IN SHANDONG PENINSULA

山东半岛蓬莱附近林格庄和下朱潘两地黄土堆积中发现了火山玻璃 ,这些火山玻璃可能来源于邻近地区第四纪的火山活动和当地第三纪末、第四纪初期火山灰物质的“海洋沉积—风力改造再沉积”,也可能是在气候转换时期当地处于山顶位置的火山灰物质的再搬运 (经风力作用或坡面流水作用 )沉积。若是第一种来源 ,则这些火山玻璃具有重要的地层学和年代学意义 ;若是第三种来源 ,则这些火山玻璃是气候环境转换时期气候环境剧烈动荡的反映。

In this paper,volcanic glass discovered in loess at Xiazhupan and Lingezhuang,two places near Penglai County Town in Shandong Peninsula is discussed.The paper gives an explanation to the possible sources of the volcanic glass and also their implications.The glass has three possible sources,namely, (1)Quaternary eruption of the nearby volcanoes,such as Changbaishan and the volcanoes in Japan.If so,the glass could represent some instants of geological time and will be very important for loess dating and stratigraphy;(2)marine deposits of the Bohai Sea,which contain tephra and serve as the main source of loess around the Bohai Sea.The tephra contained in the marine deposits of the Bohai Sea comes from Shandong Peninsula where strong volcanic activities occurred at the end of Neogene or at the beginning of Quaternary and thus a thick layer of tephra sediments has been deposited;and (3)the tephra materials formed at the end of Neogene or at the beginning of Quaternary,which are found lying at the top of the hills around Lingezhuang and Xiazhupan at present.During storm periods when there were strong wind and rain,the tephra may have been transported by wind or slope flows from the top of the hills to the foot of the hills and then settled there.