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根据长江中下游地区中生代火山岩与成矿作用的研究现状,选择研究工作较为薄弱的、最东端的溧水盆地火山岩为研究对象,进行了详细的锆石U-Pb同位素分析,并结合本区4个不同中生代火山盆地火山岩地球化学、岩性地层学资料,对各盆地中4个火山旋回的火山岩进行了对比研究.研究表明:溧水盆地龙王山组粗面岩的结晶年龄为128Ma,这标志着长江中下游地区由西向东中生代火山作用的全面展开.4个火山旋回的时代分别为:>125Ma、125～120Ma、120～110Ma和110～90Ma.庐枞盆地的浮山组与宁芜盆地的姑山组+娘娘山组(即溧水盆地的观山组+甲山组)对应较为恰当,应属第三火山旋回.本区白垩世火山岩的地球化学特征,反映这些幔源碱性岩浆在上升过程中受到了陆壳物质的混染,早期火山岩(如溧水盆地龙王山组)则是Sr矿的矿源层.
According to the research status of the Mesozoic volcanic rocks and mineralization in the middle and lower reaches of the Yangtze River, volcanic rocks in the Lishui Basin, the weakest in the research area, are selected for the study. U-Pb zircon isotope analyzes are conducted in detail. The volcanic rocks volcanic rocks from different volcanic basins in different Mesozoic volcanic basins have been compared with four volcanic volcanic rocks in the basin.The study shows that the crystallization age of the Longwangshan Formation trachyte in Lishui Basin is 128 Ma, Middle and lower reaches of the region from the west to the East Mesozoic volcanic full swing.The four volcanic cycles are:> 125Ma, 125 ~ 120Ma, 120 ~ 110Ma and 110 ~ 90Ma. The Fushan Formation in Luzong Basin and Ningwu basin The group + Niangniang Mountain Formation (ie, the Guanshan Formation + Mt. Formation in Lishui Basin) is correspondingly appropriate and should belong to the Third Volcanic Cycle.The geochemical characteristics of the Cretaceous volcanic rocks in this area reflect that these mantle-derived alkaline magmas were subjected to ascending processes The continental crust material contamination, early volcanic rocks (such as Lishui basin Longwangshan Formation) is the source of Sr ore.