Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ag...Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ages of the established Middle and Upper Proterozoic sequence stratigraphic framework in the Ming Tombs area lying in western Yanshan Mountain of Beijing. Besides, sketchy determination of δ13C and δ18O was also performed for other formations and members. The analytical results show the following: under the condition of clear-water carbonate sediments, δ13C and δ18O, featuring smaller variation of δ13C but larger variation of δ18O, can well delineate the relative change of sea level, which reflects the difference of primary sedimentary settings; in the presence of terrigenous substances, δ13C values vary greatly while δ18O slightly; the carbon and oxygen isotopes show marked changes at sequence boundaries. Besides, particular patterns can be found in regard to the distribution of carbon and oxygen isotopes within the sequences.展开更多
The Mesoproterozoic Changcheng System is widely distributed in the North China Craton. Determining its time of deposition and sources is important to understand the Precambrian crustal evolution of the North China Cra...The Mesoproterozoic Changcheng System is widely distributed in the North China Craton. Determining its time of deposition and sources is important to understand the Precambrian crustal evolution of the North China Craton. This paper suggests age distribution patterns for detrital zircons from clastic sediments of the Changcheng System in the Ming Tombs area, Beijing. Samples of feldspar-bearing sandstone (CHc-2) and pure sandstone (CHc-9) were collected from the Changzhougou Formation, which constitutes the basal part of the Changcheng System. Detrital zircons show an age range from 2.35 to 2.60 Ga. However, sample CHc-9 in the upper Changzhougou Formation also contains some zircons with ages of 1.9-1.8 Ga and 2.3-2.1 Ga. The age patterns lead to the following conclusions: (1) Most of the detrital material came from a source area composed predominantly of ~2.5 Ga continental crust of the North China Craton; (2) 1.9-1.8 Ga reflects the age record of Palaeoproterozoic continent-continent collisional event in the North China Craton; and (3) the oldest age for deposition of the Changcheng System is 1.8 Ga.展开更多
Many abnormal sedimentary structures in the Precambrian carbonate strata of the Ming Tombs District,Beijing, are recognized by the author as a probable earth- quake-tsunami sequence. These structures include a series ...Many abnormal sedimentary structures in the Precambrian carbonate strata of the Ming Tombs District,Beijing, are recognized by the author as a probable earth- quake-tsunami sequence. These structures include a series of soft sedimentary de- formation and elasticoplastic folding and are implicated not only in geological cat- astrophic events but also more or less in the prediction of recent earthquakes.展开更多
Built between 1368 and 1911, The Imperial Tombs of the Ming （1368- 1644） and Qing （1644-1911） dynaslies includes Xianling Tombs of theMing Dynast）. Eastern and Western Qing Tornbs, Xiaoling Tomb of the Ming Dynasty.
文摘Abstract: This paper discusses the distribution pattern and geological significance of the carbon and oxygen isotopes (δ13C and δ18O) in the depositional sequences of Gaoyuzhuangian, Yangzhuangian and Wumishanian ages of the established Middle and Upper Proterozoic sequence stratigraphic framework in the Ming Tombs area lying in western Yanshan Mountain of Beijing. Besides, sketchy determination of δ13C and δ18O was also performed for other formations and members. The analytical results show the following: under the condition of clear-water carbonate sediments, δ13C and δ18O, featuring smaller variation of δ13C but larger variation of δ18O, can well delineate the relative change of sea level, which reflects the difference of primary sedimentary settings; in the presence of terrigenous substances, δ13C values vary greatly while δ18O slightly; the carbon and oxygen isotopes show marked changes at sequence boundaries. Besides, particular patterns can be found in regard to the distribution of carbon and oxygen isotopes within the sequences.
基金supported by the National Seience Foundation of China(Grant No.40172044).
文摘The Mesoproterozoic Changcheng System is widely distributed in the North China Craton. Determining its time of deposition and sources is important to understand the Precambrian crustal evolution of the North China Craton. This paper suggests age distribution patterns for detrital zircons from clastic sediments of the Changcheng System in the Ming Tombs area, Beijing. Samples of feldspar-bearing sandstone (CHc-2) and pure sandstone (CHc-9) were collected from the Changzhougou Formation, which constitutes the basal part of the Changcheng System. Detrital zircons show an age range from 2.35 to 2.60 Ga. However, sample CHc-9 in the upper Changzhougou Formation also contains some zircons with ages of 1.9-1.8 Ga and 2.3-2.1 Ga. The age patterns lead to the following conclusions: (1) Most of the detrital material came from a source area composed predominantly of ~2.5 Ga continental crust of the North China Craton; (2) 1.9-1.8 Ga reflects the age record of Palaeoproterozoic continent-continent collisional event in the North China Craton; and (3) the oldest age for deposition of the Changcheng System is 1.8 Ga.
文摘Many abnormal sedimentary structures in the Precambrian carbonate strata of the Ming Tombs District,Beijing, are recognized by the author as a probable earth- quake-tsunami sequence. These structures include a series of soft sedimentary de- formation and elasticoplastic folding and are implicated not only in geological cat- astrophic events but also more or less in the prediction of recent earthquakes.
文摘Built between 1368 and 1911, The Imperial Tombs of the Ming （1368- 1644） and Qing （1644-1911） dynaslies includes Xianling Tombs of theMing Dynast）. Eastern and Western Qing Tornbs, Xiaoling Tomb of the Ming Dynasty.
