Rockmagnetic Characteristics of the Late CretaceousEarly Miocene Sediments on the Kuzigongsu Section of the Northwestern Tarim Basin

Key words: 
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• rock magnetism /
• sedimentary settings /
• Late Cretaceous to Early Miocene /
• Western Tarim Basin /
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Abstract:  We have carried out an rock magnetism investigation and thermal demagnetization for the Late Cretaceous to Early Miocene sediments on Kuzigongsu section from the Northwestern Tarim basin, Western China. The results indicate that thermal demagnetization and rock magnetic characteristics of rocks can be divided into three types specifically. Rocks from sublittoral zone, shallow of platform edge are dominated by the pseudosingle domain (PSD) magnetite with a little amount of goethite and maghematite. Its natural remanence intensity is smaller than 1×10-2A/m generally, and the characteristic remanent magnetism (ChRM) are carried by magnetite and can be isolated from 250℃~500℃. Rocks from intertidal zone and supratidal zone are dominated by pseudosingle domain and multidomain(PSD﹢MD) magnetite generally, with a little amount of goethite,maghematite and hematite. It’s natural remanence intensity is between 1×10-2~1A/m,and the characteristic remanent magnetism (ChRM) are carried by magnetite and can be isolated from 250℃~580℃.Rocks from the fluvial and lacustrine facies are dominated by the pseudosingle domain(PSD) magnetite, the hematite, with a little amount of maghemite, the goethite, Its natural remanence intensity is greater than  1 101A/m generally, and the characteristic remanent magnetism (ChRM) are carried by hematite in most samples,and carried by magnetite and hematite in some samples. So investigation of rock magnetism on sediments from different sedimentary environments is important for the paloemagnetic research.