吉林晚石炭世威宁期石头口门裂陷槽的发现及地质意义

吉林晚石炭世要期石头口门裂陷槽位于长春东５０ｋｍ。该裂陷槽以海底火山沉积－－硅质岩沉积为主。早期以含锰结核的碎屑岩和泥岩、硅质岩为主，并有少量的凝灰碉和玄武岩；中期以海底火山喷发的高钠质细碧岩、角地为主，并伴有规模不大的蛇纹岩；晚期以硅质岩、长石杂砂岩、泥岩、生物碎屑灰岩为主，在生物碎屑灰岩中首次发现Ｆｕｓｕｌｉｎａ ｌａｎｃｅｏｌａｔａ Ｆ．ｓｐ．、Ｐｓｅｕｄｏｓｔａｆｆｅｌｌａ ｋｈｏｔｕｎｅ

Discovery of Late Carboniferous Weining Age Fauna from Shitou-koumen Faulted Trough Basin in Jilin and its Implication

The Shitoukoumen faulted trough basin is situated 50 km east of Changchun, Jilin, Northeast China. It is dominated by clastic rocks of manganese nodules, mudstone and silicalite intercalated with minor tuff and basalt in the lower part; by high sodium spilite and keratophyre from submarine volcanic eruptions, associated with serpentinite in the middle; and by silicalite, felds-pathic greywacke, mudstone and bioclastic limestone in the upper part. Rich fossils including Fusulina lanceolata, F. sp. , Pseudostaffella khotunensis, P. sp. , Schubertella sp. and En~ dothyre sp. have been found for the first time from the bioclastic limestone. The sediments can thus be dated to the Weining Age of Late Carboniferous. The sediments in the Shitoukoumen faulted trough basin have typical features of the spilite and keratophyre assemblage of submarine volcanic sediments. They display the process of sinking-rising and pull-apart of the faulted trough basin, reflecting the intensity of pull-apart and the comparatively thinner part of the Earth's crust. The sediments are distinct in the lithological characters, which are different from the contemporary strata in Jilin Province and other regions, therefore a new lithostratigraphic u-nit, the Shitoukoumen Formation is erected to represent the late Carboniferous volcanic rock series in Jilin.