Environmental Magnetic Characteristics Of The Kasimovian-Gzhelian(Carboniferous)Marine Sequence Of The Naqing Section In South China

The Carboniferous was an important period in the evolution of the late Paleozoic earth.The global tectonic activity was relatively intense,accompanied by biological events and climate changes,and it was an important stage in the development of the Late Paleozoic glacial period.The rise and fall of the glaciers led to frequent changes in sea level during this period,which could be as high as more than 100 meters.In the Late Carboniferous in south China,the sedimentary strata of Kasimovian-Gzhelian?307.0²98.9 Ma?recorded the process of transgression,formed the carbonate rock deposition with very continuous development,and recorded the abundant paleoclimate and paleoenvironmental information.In this paper,the Carboniferous Kashimovian-Gzhelian?307.0²98.9 Ma?sedimentary strata in the Naqing section of South China were continuously sampled at intervals of 5 cm and detailed environmental magnetic studies were conducted to investigate environmental magnetic parameters how to respond to the impact of climate change in the paleoclimate and paleoenvironment of the Kasimovian-Gzhelian.The results showed that the variation range of value was?-1.01⁶.01?×10^-8m³/kg,with an average value of 1.24×10^-88 m³/kg.?-T curves and hysteresis loops show that the magnetic minerals are mainly paramagnetic clays and diamagnetic carbonate rocks,containing a small amount of magnetite and high coercive minerals(such as hematite.The correlation between mass susceptibility???,non-hysteresis residual magnetization?ARM?and thorium elements suggests that they may have similar origins,both from terrestrial inputs.This paper also found that the variation trend of?¹⁸O value of environmental magnetic parameters was consistent with that of conodontic apatite,that is,when the climate became cold,?¹⁸O value increased,and the values of SIRM and ARM also increased.On the contrary,the value of?¹⁸O decreased and the values of SIRM and ARM also decreased in a warm environment.Therefore,environmental magnetic parameters can be used as indicators of terrestrial input of the ocean system and paleoclimate paleoenvironmental changes.That is,the lower the sea level,the greater the input of terrestrial materials,and the higher the magnetic parameter values such as?,SIRM,and?_ARM.