The Records of (delta)¹⁸O and (delta)¹³C for Climate Changes in Nihewan Basin during the Last Interglacial

Abstract:

According to the variation of stable isotopic composition of carbonate in lacustrine deposited in Hutouliang, Nihewan Basin, the section can be subdivided into four oxygen-carbon-isotope stages. They are as follows from top downwards: (1) 0.00-1.85m, which gave lower value of oxygen and carbon isotope. The (delta)¹⁸O value of 4 samples ranges from -7.16 to -7.88, (delta)¹⁸O(avg)=-7.53; the (delta)¹³C value ranges from -3.40 to -5.57, (delta)¹³C(avg)= -4.30. (2) 1.85-7.00m, which gave higher value of oxygen and carbon isotope. The (delta)¹⁸O value of 12 samples ranges from 0.46 to -5.52, (delta)¹⁸O(avg)= -2.59; the (delta)¹³C value ranges from 0.23 to -3.66, (delta)¹³C(avg)= -1.17. (3) 7.00-10.10m,which gave lower value of oxygen and carbon isotope. The (delta)¹⁸O value of 4 samples ranges from -6.97 to -9.39, (delta)¹⁸O(avg)= -8.50; the (delta)¹³C value ranges from -2.68 to -6.85, (delta)¹³C(avg)= -4.04. (4)10.10-14.87 m, which gave higher value of oxygen and carb on isotope. The (delta)¹⁸O value of 11 samples ranges from 0.57 to 6.36, (delta)¹⁸O(avg)= -2.94; the (delta)¹³C values ranges from 3.43 to -3.52, (delta)¹³C(avg)= -0.73. Generally, the values of (delta)¹⁸O and (delta)¹³C of carbonate in lacustrite sediment have a positive correlation with that of the water saltness, the saltness has a positive correlation with evaporativity, and the evaporativity has a positive correlation with temperature and a negative correlation with humidity. So the high value of oxygen and carbon isotope ((delta)¹⁸O and (delta)¹³C) in Nihewan represents a relatively hot and dry weather while the low value of which represents a rather cool and wet weather. The variation of oxygen and carbon isotopic value among the section indicates the alternation between hot-dry and cool-wet climate during the last interglacial period.

Key words:

(delta)¹⁸O; (delta)¹³C; Nihewan Basin; last interglacial period

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