This note presents a new result of terrestrial mollusk study from the Luochuan loesssection since the last 250 ka. A total of 213 samples, taken at intervals of 10 cm in the S0-L3 portion, were analyzed for fossil mol...This note presents a new result of terrestrial mollusk study from the Luochuan loesssection since the last 250 ka. A total of 213 samples, taken at intervals of 10 cm in the S0-L3 portion, were analyzed for fossil mollusks. Generally, 150-600 individuals were counted in each sample. According to the distribution of mollusk fossil assemblages in the loess section, 11 mollusk fossil zones have been recognized, representing different climatic and ecological conditions. Three main ecological groups were identified according to the temperature and moisture requirements of each taxon. The cold-aridiphilous group shows maxima at about 240-220, 190-182, 150-140 and 74 -66 ka BP. The thermo-humidiphilous set has high abundances for at least 6 times in the section at about 246-240, 220-216, 170-158, 92-86, 60-44 and 10 kaBP. Our results show that variations in mollusk ecological groups are related with changes in the Earth orbital parameters at the 41 and 20 ka frequencies. Maxima in thermo-humidiphilous taxa展开更多
文摘This note presents a new result of terrestrial mollusk study from the Luochuan loesssection since the last 250 ka. A total of 213 samples, taken at intervals of 10 cm in the S0-L3 portion, were analyzed for fossil mollusks. Generally, 150-600 individuals were counted in each sample. According to the distribution of mollusk fossil assemblages in the loess section, 11 mollusk fossil zones have been recognized, representing different climatic and ecological conditions. Three main ecological groups were identified according to the temperature and moisture requirements of each taxon. The cold-aridiphilous group shows maxima at about 240-220, 190-182, 150-140 and 74 -66 ka BP. The thermo-humidiphilous set has high abundances for at least 6 times in the section at about 246-240, 220-216, 170-158, 92-86, 60-44 and 10 kaBP. Our results show that variations in mollusk ecological groups are related with changes in the Earth orbital parameters at the 41 and 20 ka frequencies. Maxima in thermo-humidiphilous taxa
