长江中下游地区怀宁盆地火山岩锆石LA-ICPMS定年

Huaining basin is one of the many Mesozoic volcanic basins in the Middle and Lower Yangtze Valley, where from the bottom to up the volcanic rocks of Pengjiakou and Jiangzhen formations distributed. The rock types are dominantly andesitic tufflava and basaltic trachyandesit. Zircon LA-ICPMS U-Pb isotopic dating on the volcanic rocks from Pengjiakou and Jiangzhen formations gives weighted mean 206Pb/204Pb ages of 130.0±1.7 Ma (MSWD=0.73) and 130.5±1.7 Ma (MSWD=0.78), respectively. Indicating they erupted in the early Cretaceous and a briefly active duration. The ages of volcanic rocks in Huaining basin are consistent with that of other basin distributed in the Middle and Lower Yangtze Valley, suggesting that erupted ages of the Mesozoic volcanic rocks in the Middle and Lower Yangtze Valley concentrated in a period of 135 to 127 Ma and the volcanic rocks were derived from partial melting of lithospheric mantle under a intense extended setting.