中更新世以来中国东部六次海侵及其天文气候学的解释

AN ASTROCLIMATOLOGICAL EXPLANATION OF SIX MARINE TRANSGRESSIONS IN EASTERN CHINA SINCE MIDDLE PLEISTOCENE

自中更新世以来(在过去的73万年内),中国东部地区曾发生过六次海侵。如果考察该期间全球各地各季所获得的太阳辐射量,那么上述六次海侵的时期恰好都是全球所获得的、北半球冬半年的、平均的太阳辐射量相对较多的日时期,亦即气候较暖的时期。因为后者是地球轨道三要素(黄道倾斜、偏心率,岁差运动)自然变化的产物,故中国东部的海侵活动归根到底是地球轨道自然变化的结果之一。

Six marine transgressions (HI-HVI) have been revealed from eastern China since Middle Pleistocene (730,000 years ago), which are: HI, 11,000 years B P., correlated with oxygen isotope stage 1; H1I, 21,000-29,000 years B. P. substage 3a; HIII, substage 3c, the weakest among the six marine transgressions'; HIV, 70,000-128,000 years B. P., with three marine beds, corresponding to substages 5a, 5c and 5e respectively; HV, stage7; HVI, stage 15(1-4). Therefore, all these marine transgressions occurred in warm stages, glacier melted, thus the sea level rose and the transgressions happened (5-9). Why did the six marine transgressions occur in these stages? There is no accepted theory to explain the phenomenon. We think that astroclimatology can explain it. The Milankovitch theory has been extensively accepted (Hays, Imbrie and Shackleton, 1976; Berger, Imbrie, Hays, Kukla and Saltzman, 1984) (10, 11). The theory holds that changes in earth's orbital geometry are the fundamental cause of the succession of Quaternary ice ages. It has been verified by the spectrum analysis (10, 11). However, Berger, Imbrie, Hays, Kukla and Saltzman (1984) said, 'The theory was apparently in conflict with substantial geological evidence that the two hemispheres entered and left glacial states at approximately the same time' (11). It is true that the deviations of incoming solar radiation in the caloric winter northern hemisphere and in the caloric winter southern hemisphere are almost opposite (Vernekar, 1972; Bergcr, 1978)(12,13). Why did the two hemisphere enter and leave glacial states at the same time if they received different incoming solar radiation? This conflict exists for the last 730,000 years. In 1988 and 1991, we pointed out another conflict. The deviations of incoming solar radiation in winter and summer are almost opposite (Vernekar,1972; Berger, 1978) (12, 13), while the variations of temperature in both winter and summer are similar (Berger, Imbrie, Hays, Kukla and Saktzman, 1984; Xu Qinqi, 1988) (11, 14). It is quite evident that the two conflicts mentioned above are in the same way. In 1988 and 1991, the average incoming solar radiation in the winter half-year of the northern hemisphere on the earth's surface in each oxygen isotope stage(Di) was calculated (Table) (14, 15). We found that the relationship between Di and the worldwide winter temperature is in roughly positive correlation. This principle i's named the First Law of Astrocli-matology (14, 15). The relationship between Xi (the average incoming solar raciation in the summer half-year of the northern hemisphere on the earth's surface in each stage) and the worldwide summer temperature is in approximately negative correlation. This principle is called the Second Law of Astr-oclimatology. Because the variation of temperature both in winter and summer are similar, the climate changed regularly in accordance with the variation of Di in Table during the last 730,000 years. We explained the four Classical North European Glacial Stages by making use of the data of Di of Table in 1991 (16). Now we explain the six marine transgressions in eastern China also with the data. In the Middle Pleistocene, there are two outstanding warm stages, i. e. stages 15 and 7 (7, 8). Their absolute values of Di are 461.41 ly/day (stage 15) and 461.05 ly/day (stage 7) (Table). Although D7 is larger than D15, the duration of stage 15 is about 58,000 years, much longer than that of stage 7 (Table). Therefore, it is natural that HVI (Transgression VI) occurred in stage 15. After stage 15, D7 is the largest among all the Di (Table). So it is undoubtedly logical that HV (Transgression V) occurred in stage 7. Because the climate changed regularly in accordance with the variations of the average incoming solar radiation in the winter half-year of the northen hemisphere, and the incoming solar radiation is equal to the outgoing earth radiation at 35癗 (17), it appears certain that the distribution of winter hal-fyear radiation at 35癗 in the northern hemisphere would be critical to the variation