We studied the sedimentary characteristics of a Paleocene-Eocene salt lake in the Jiangling Depression through field core observation,thin section identification,scanning electron microscopy,and X-ray diffraction anal...We studied the sedimentary characteristics of a Paleocene-Eocene salt lake in the Jiangling Depression through field core observation,thin section identification,scanning electron microscopy,and X-ray diffraction analysis.On the basis of sedimentary characteristics we have summarized the petrological and mineralogical characteristics of the salt lake and proposed 9 types of grade IV salt rhythms.The deposition shows a desalting to salting order of halite-argillaceous-mudstone-mud dolostonemud anhydrock-glauberite-halite.The relationship among grade IV rhythms,water salinity and climate fluctuations was analyzed.Based on the analysis of the relationship between boron content and mudstone color and by combining the mineralogy and sedimentary environment characteristics,we propose that the early and late Paleocene Shashi Formation in the Jiangling Depression was a paleolacustrine depositional environment with a high salt content,which is a representation of the shallow water salt lake depositional model.The middle Paleocene Shashi Formation and the early Eocene Xingouzui Formation were salt and brackish sedimentary environments with low salt content in a deep paleolake,which represents a deep salt lake depositional model.展开更多
Mounting evidence indicates that the orbital period of the solar system’s movement through the Milky Way has had a controlling effect on processes of the Earth’s system throughout the Phanerozoic.To decipher the res...Mounting evidence indicates that the orbital period of the solar system’s movement through the Milky Way has had a controlling effect on processes of the Earth’s system throughout the Phanerozoic.To decipher the response of a given terrestrial basin’s rhythms to galactic dynamics,for the first time,we report long-term cycles recorded in the Mesozoic Ordos Basin(Central China).The astronomical time scale(ATS)was established for each successive sedimentary sequence,and the duration of unconformity episodes was estimated based on the chronological constraints.Using this timescale,time-series analysis of the deposition rate is carried out through the Mesozoic Ordos Basin,which reveals compelling periodicities of 93,33,9,3-5,and 2.4Myr.The radial solar system motions around the galactic centre and plate tectonic cycles act cooperatively to impact the magmatic tempo of the Qinling orogenic belt and the 93-Myr depositional cycle of the Mesozoic Ordos Basin.The Mesozoic 33-Myr cycle is a sedimentary response to the half-period of the solar system’s vertical oscillation about the galactic plane.A rational explanation is that galactic oscillation affects mantle convection,which is responsible for periodic asthenospheric upwelling and ultimately controls the vertical crust oscillation of the Ordos Basin.Mesozoic 9-Myr and the higher-frequency 3-5and 2.4-Myr depositional cycles can be sedimentary responses to the Earth’s orbital eccentricity,which affected the temporal variation in depositional environments in the Ordos Basin.Apart from the galactic-geologic correlations,long-term cycles recorded within a sedimentary basin should also consider the tectonically driven mechanisms at these timescales.This framework provides a new perspective for revealing the astronomical origin of Earth’s rhythms.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(No.20011CB403007)the National Natural Science Foundation for Young Scientists of China(Nos.41502089,41202059)+1 种基金the Central Public Welfare Scientific Research Basic Scientific Research Business Expenses(No.K1415)the Geological Survey(No.1212010011808)
文摘We studied the sedimentary characteristics of a Paleocene-Eocene salt lake in the Jiangling Depression through field core observation,thin section identification,scanning electron microscopy,and X-ray diffraction analysis.On the basis of sedimentary characteristics we have summarized the petrological and mineralogical characteristics of the salt lake and proposed 9 types of grade IV salt rhythms.The deposition shows a desalting to salting order of halite-argillaceous-mudstone-mud dolostonemud anhydrock-glauberite-halite.The relationship among grade IV rhythms,water salinity and climate fluctuations was analyzed.Based on the analysis of the relationship between boron content and mudstone color and by combining the mineralogy and sedimentary environment characteristics,we propose that the early and late Paleocene Shashi Formation in the Jiangling Depression was a paleolacustrine depositional environment with a high salt content,which is a representation of the shallow water salt lake depositional model.The middle Paleocene Shashi Formation and the early Eocene Xingouzui Formation were salt and brackish sedimentary environments with low salt content in a deep paleolake,which represents a deep salt lake depositional model.
基金supported by the National Natural Science Foundation of China(Grant Nos.42102166,42090025,and 41625009)。
文摘Mounting evidence indicates that the orbital period of the solar system’s movement through the Milky Way has had a controlling effect on processes of the Earth’s system throughout the Phanerozoic.To decipher the response of a given terrestrial basin’s rhythms to galactic dynamics,for the first time,we report long-term cycles recorded in the Mesozoic Ordos Basin(Central China).The astronomical time scale(ATS)was established for each successive sedimentary sequence,and the duration of unconformity episodes was estimated based on the chronological constraints.Using this timescale,time-series analysis of the deposition rate is carried out through the Mesozoic Ordos Basin,which reveals compelling periodicities of 93,33,9,3-5,and 2.4Myr.The radial solar system motions around the galactic centre and plate tectonic cycles act cooperatively to impact the magmatic tempo of the Qinling orogenic belt and the 93-Myr depositional cycle of the Mesozoic Ordos Basin.The Mesozoic 33-Myr cycle is a sedimentary response to the half-period of the solar system’s vertical oscillation about the galactic plane.A rational explanation is that galactic oscillation affects mantle convection,which is responsible for periodic asthenospheric upwelling and ultimately controls the vertical crust oscillation of the Ordos Basin.Mesozoic 9-Myr and the higher-frequency 3-5and 2.4-Myr depositional cycles can be sedimentary responses to the Earth’s orbital eccentricity,which affected the temporal variation in depositional environments in the Ordos Basin.Apart from the galactic-geologic correlations,long-term cycles recorded within a sedimentary basin should also consider the tectonically driven mechanisms at these timescales.This framework provides a new perspective for revealing the astronomical origin of Earth’s rhythms.
