摘要
在广西和贵州泥盆系-石炭系界线有强烈的δ^(13)C值负异常,两地负异常可以对比。在广西和湖南弗拉阶顶部δ^(13)C值有多次负异常,两地负异常亦可以对比,δ^(13)C值波动曲线具有显著特征,它为今后弗拉阶-法门阶界线的识别及远距离对比具有实际应用价值。在生物地层工作基础上,对无机碳同位素的研究,在一定条件下可以提高远距离对比的精度。
The D-C boundary shale below the Siphonodella sulcata Zone of Huangmao Section, Guangxi, and Muhua Section, Guizhou reveal negative perturbation ofδ13C values of 17‰ and 13‰ respectively. Correlation between Huangmao Section and Muhua Section based on conodont succession can be well confirmed by the δ13C value curves. At Nandong Section, Guangxi, within the Palmatolepis linguiformis Zone (i. e. Uppermost gigas Zone)of the uppermost Frasnian, there are three horizons revealing δ13C negative perturbation, the lowest one is of 6‰. The Nandong Section bear pelagic fossils, and the F-F boundary can be well defined by the extinction of the conodont species Palmatolepis gigas, Pa. linguiformis and the first occurence of Pa. triangularis which was recommended by the Subcommission on Devonian Stratigraphy as the marker of the base of the Famennian. The Xikuangshan Section, Hunan, bear neritic fossils and lacks marker species. It is assumed that the F-F boundary should be placed at the level above the mass extinction line of reef corals and bryozoa, beneath the first occurence of neritic conodont species Icriodus deformatus Han. Thus the F-F boundaries of Nandong and Xikuangshan are correlated roughly by indirect biostratigraphic method which needs collateral evidence. The biostratigraphic result can be elaborated by the δ13C data. The extinction line of the reefs at Xikuangshan is somewhat lower than the F-F boundary defined by the conodonts at Nandong. The δ13C fluctuation curve of the F-F boundary has prominent feature, that under certain condition it has the potentiality for long-range correlation.
出处
《北京大学学报（自然科学版）》
CAS
CSCD
北大核心
1990年第4期497-505,共9页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金会
国家教委科学技术基金会
关键词
泥盆纪
碳稳定同位素
地层对比
Carbon stable isotope
Stratigraphic correlation
Devonian
