Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite

Details Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite

Feb 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004geoji.156..267l&link_type=abstract

Geophysical Journal International, Volume 156, Issue 12, pp. 267-274.

Astronomy and Astrophysics

Astronomy

11

Aeolian, Chinese Loess, Low-Temperature Properties, Pedogenesis

Scientific paper

This paper proposes a new method to distinguish between interglacial deposits and pedogenically-overprinted glacial loess based on the concentration variations of coarse-grained aeolian (magnetically pseudo-single domain and multidomain) magnetite. We apply the method to a sequence from the upper part of the loess unit L2 (marine isotope stage MIS 6) to the sub-loess unit S1L2 (MIS 5d) at the YuanBo (YB) section in the Chinese Loess Plateau. The method is based on the differences in low temperature properties between the coarse-grained (multidomain and pseudo-single domain) detrital magnetite and the pedogenic magnetic particles including superparamagnetic (SP) particles and relatively larger (>SP) maghemite particles. The former is characterized by a crystallographic Verwey transition around 120 K. In contrast, the magnetization of the latter continuously decreases in intensity with increasing temperatures. The method involves two steps: (1) calculating the first-derivative of the low temperature thermal demagnetization of the saturated isothermal remanent magnetization acquired at 20 K (LT-SIRM), which enhances the behaviour related to the Verwey transition, and (2) fitting a third-order polynomial background to the data between both 50-70 and 150-300 K, and then subtracting this background from the total derivative curves. The area under the background-corrected derivative curves represents the absolute intensity drop associated with the Verwey transition (ΔJTV). This is caused by the aeolian coarse-grained magnetite, which is very sensitive to the changes in the intensity of the winter monsoon, and in turn related to the changes in palaeoclimate. The results show that the sharp drop of ΔJTV at 39.44 m corresponds to the climatic boundary from L2 (MIS 6) to S1S3 (MIS 5e), and not at 39.8 m as thought previously. Thus, the palaeosol deposits just below this boundary are in fact highly altered L2 materials instead of S1S3 accumulations.

Affiliated with

Also associated with

No associations

Rating

Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1019214