摘要
位于大别造山带北部的合肥盆地 ,其中的沉积是造山带剥露历史的重要记录。自生伊利石K -Ar测年 ,证实了合肥盆地中部安参 1井自上而下钻遇了下白垩统 ,上、中、下侏罗统 ,下二叠统和上石炭统地层 ,下伏为奥陶系。中生界砂岩碎屑组分分析 ,表明其源区为大别造山带。安参 1井内下二叠统砂岩不含造山带来源的碎屑多硅白云母。自下侏罗统至下白垩统 ,钻遇的砂岩中连续出现了丰富的碎屑多硅白云母 (Si>3.3)。这不但指示大别造山带是合肥盆地的主要物源区 ,也限定了大别高压 -超高压变质岩在早侏罗世早期就已经剥露地表 。
Sediments in the Hefei basin to the north of the Dabie orogen are important records of unroofing history for the orogen. K-Ar dating of authigenic illite proves that strata in drill-hole Ancan-1 from top to bottom are lower Cretaceous, upper-mid-lower-Jurassic, lower Permian and upper Carboniferous strata which are probably underlain by Ordovician strata. Detrital composition analysis of the Mesozoic sandstones indicates that their provenance is the Dabie orogen. Lower Permian sandstones in drill-hole Ancan-1 do not contain detrital phengite from orogen. Rich phengite (Si>3.3) detritus occurs continuously in sandstones from lower Jurassic to lower Cretaceous strata in the drill-hole. This shows that the Dabie orogen is main provenance for the Hefei basin, and indicates that HP to UHP metamorphic rocks of the orogen were unroofed since the earliest Early Jurassic and exposed continuously since then.
出处
《高校地质学报》
CAS
CSCD
2004年第4期594-605,共12页
Geological Journal of China Universities
基金
国家自然科学基金 (4 0 2 72 0 94 )资助
