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晚更新世末期的地磁短期反极性事件,是由邦赫梅特(N.Bonhommet)和巴肯(J.Babkine)于法国拉斯钱普山(Puy de Laschamp)首先发现的。近十几年来,各国的某些古地磁研究者先后发表了数十篇论文对该事件的时代进行过讨论,但到目前为止,尚无较为一致的意见。根据已发表的年代资料,大体可将其归纳为两种意见:一是以莫尔尼(N.Morner)为代表,根据瑞典京城哥德堡公园的研究资料,认为该短期漂移时间应在距今13750—12350年范围内,并将其称为哥德堡事件(Gothenburg reversal);二是以威苏帕(K.L.Verosub)为代表,认为在距今21000—36000年间并不存在反向时期。而全球性的倒转时间应在距今35000—40000年间的某一时期。 根据我们对黄海,东海近岸带沉积岩芯的古地磁研究,认为晚更新世的地磁短期反极性事件,可能由两个事件组成。本文根据对沉积岩芯的系统测量、结合C~(14)测年和微 相似文献
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ANISOTROPY OF MAGNETIC SUSCEPTIBILITY AND IDENTIFICATION OF TILTED SEDIMENT CORES FROM THE BOHAI SEA
Anisotropy of magnetic susceptibility (AMS) is a well-developed technique increaseingly used in petro-fabric determination. ItS application to two Mackereth cores JX91-2A and JX91-2B, taken from thesame site in the central Bohai Sea, revealed 3D magnetic fabrics of the sediments as expressed with susce-ptibility ellipsoids. The flat seafloor and the relatively quiet depositional environment in the semi-isolatedBohai Sea should asult in a primary fabric with horisontally obate susocptibility el1ipsoids. Mormwr,the inaxing downcore totaI anisotropy comprising mainly of magntic foliation nsulting fIrom sedimentcompaction should also lead to flat ellipsoids. Therefore, the off-pole meam dindions of minimurn axes ofaseptibility ellipsoids on stermnets must indicate that the two coas are ti]ted re1ative to the flat anfloor.Use of Fisher statisties showh the tilt angles to be 14° for JX91-2A and 23°for JX91 -2B from whichthe tna depths of the coas were dedded accordingly. 相似文献
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东海DC-1, DC-2孔古地磁研究 总被引：4，自引：0，他引：4
本文报道了东海DC-1,DC-2孔古地磁研究结果,表明DC-l孔26.9m岩芯及DC-2孔61.0m岩芯段均以正极性为主,属布容正极性世 (Brunhcs)。其中DC-l孔18.86-19.18m的反向磁化带(倾角为—49.29°),经~(14)C测年为距今115lO土570a;DC-2孔29.95—30.54m处反向磁化带(倾角为—40.5°),经~(14)C测年为距今10250±lOOa。可与哥德堡事件(Gǒthcnburg)对比。对比地磁年表,DC-2孔37.80—38.0m为反极性事件与蒙哥事件(Mungo event)相当,7l.20—74.44m划为布莱克事件(B1akc event)。据此计算全新世沉积速率为2.12—2.84m/1000a,晚更新世沉积速率为O.65一O.69m/1000a。 相似文献
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地球化学研究方法广泛应用于金属成矿分区、成矿预测、矿产普查和矿产评价的实际工作中。为了确定潜在含矿性和研究今后的普查战略,摆在我们面前最重要的任务不仅是对岩石和构造杂岩进行地球化学制图和区域分区,而且还对地壳巨大地块进行地球化学定型。与黑色金属、有色金属、稀有金属、金和铀等各种不同矿床有关的前寒武纪构造含矿性取决于许多因素,但是,影响含矿性的主要取决于下列因素:1.早太古代(33±3 相似文献
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We got two cores from 10 miles east of Zhoushan islands about 29 m in water depth in 1979 and 1980.Dc1 core, 26 m long, can be divided into two layers; 0-19.4 m, brown-yellow, silty-clay, rich in foraminifera, 19.3-26 m, grey silt. DC1 core, 91 m long, 7 miles south of DC1 core. The colour for 0-16.6 m is the same as for 0-19.4 m of Dc2 core, brown silty-clay, rich in foraminifera too. The results of paleomagnetic measurements show: there are 464 specimens in DC1 and Dc2 cores altogether; AF demagnetization often shows that 95 % of all the specimens belong to normal polarity epoch, and the others are reversal ones.We consider that more stranger intensity may represent the warming period and transgression period, and vice versa. At least DC, and Dc2 cores provide such an evidence for this. It is obvious that glacial period should be low peak period of intensity, and interglacial period should be its high peak period. 相似文献