1�� The Fifth Geological Survey Bureau of Heilongjiang��Heihe 164300��Heilongjiang��China; 2�� Qiqihar Branch of Geological Survey and Research Institute of Heilongjiang��Qiqihar 161005��Heilongjiang��China; 3�� Geological Prospecting Research Institute of Nonferrous Metals of Heilongjiang��Harbin 150046��China

The Paleozoic sedimentary strata��fossils��geochemistry of intrusive rocks and the zircon U--Pb isotopic dating of Duobaoshan in Heilongjiang Province have been comprehensively studied�� They are the marine sedimentary strata from Early Ordovician to the early Late Devonian��sea-land interbeddind sediments in the late Late Devonian��and the continental fluvial and lacustrine deposits in Early Carboniferous�� It is exposed a set of granites with ( 300 ± 3 �� 357 ± 4) Ma in southeastern Duobaoshan marine basin�� Syenite fine-grained and adamellite finegrained mylonites are post-orogenic granites��and alkali granites are post-orogenic granites in A-type�� That means the Duobaoshan marine basin closed from Late Devonian��became continental sedimentary in Early Carboniferous�� and in uplift and erosion stage in Late Carboniferous-Early Permian�� The fact performed that the orogeny of Duobaoshan area began in Early Carboniferous��and post-organic extension continued from Late Carboniferous to Late or Early Permian��