CAJ | 학술논문

利用激光剥蚀电感耦合等离子质谱(LA-ICP-MS)对三峡地区二叠系茅口组牙形石的U-Th-Pb同位素年龄进行测定.结果表明该地层中牙形石的~(208)Pb/~(232)Th放射年龄为269±44 Ma,~(207)Pb/~(235)U放射年龄为256±39 Ma,接近二叠系茅口组的生物地层年龄.~(206)Pb/~(238)U的年龄为196±6 Ma,虽然准确度较高,但与前人推测的地层年龄相比偏低.此外,作者对牙形石的稀土元素(REE)组成进行了分析,并且发现牙形石的REE组成和Ce异常与古海水氧化还原条件有一定的相关性,可以指示古海水的信息.
이용격광박식전감우합등리자질보(LA-ICP-MS)대삼협지구이첩계모구조아형석적U-Th-Pb동위소년령진행측정.결과표명해지층중아형석적~(208)Pb/~(232)Th방사년령위269±44 Ma,~(207)Pb/~(235)U방사년령위256±39 Ma,접근이첩계모구조적생물지층년령.~(206)Pb/~(238)U적년령위196±6 Ma,수연준학도교고,단여전인추측적지층년령상비편저.차외,작자대아형석적희토원소(REE)조성진행료분석,병차발현아형석적REE조성화Ce이상여고해수양화환원조건유일정적상관성,가이지시고해수적신식.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to establish radiometric U-Th-Pb ages and produce the records of rare earth elements (REE) of conodont of the Permian Maokou Formation in the Three Corges area. Fourteen spots on the sample indicate a radiometric ~(208)Pb/~(232)Th age of 269±44 Ma and a radiometric ~(207)Pb/~(235)U age of 256±39 Ma, which are consistent with the biostratigraphic ages of the Permian Maokou Formation. The age of ~(206)Pb/~(238)U is 196±6 Ma, which is relatively lower compared with the stratigraphic ages predicted by preresearchers. The paleochemical characteristics of paleoseawater from the Permian conodont were reconstructed through contrastive researches of REE and Ce anomalies. The resuts show that geochemical characteristics of the conodont may be regarded as a useful proxy to reconstruct the paleoenvironment.