Palaeomagnetic and palaeontological dating of a section at Gioia Tauro, Italy: Identification of the Blake Event
Palaeomagnetic and palaeontological dating of a section at Gioia Tauro, Italy: Identification of the Blake Event
复制标题
意大利焦亚陶罗剖面的古地磁和古生物学测年：布莱克事件的识别
DOI：
10.1016/0012-821x(80)90139-9
复制
发表时间：
1980
影响因子：
5.3
通讯作者：
A. Jacobs
中科院分区：
文献类型：
--
作者：
K. Creer;P. Readman;A. Jacobs
描述了从意大利雷吉奥迪卡拉布里亚(38°N，16°E)一个250米长的无定向岩芯中提取的样品的古地磁学和古生物研究。200米以下的岩心穿透了近海粘土，对岩心裂解剖面的肉眼观察表明，沉积没有明显的断裂。在200Oe交变退磁后，古地磁倾角测井在110m处显示了布伦斯/松山界线，低于该界线即可识别出松山时代的Jaramillo和Olduvai事件。这种磁性地层学的解释得到了古生物学证据的支持。据估计，粘土的堆积速度大约在60到190毫米/年之间，松山时代的总体平均速度约为90毫米/年。假设这一平均速率持续到布鲁内斯时代，粘土单元顶部的年龄估计约为9万年B.P.。距粘土不整合顶面约5m处，倾斜的分裂序列被解释为布莱克事件的记录，总的平均沉积速率意味着其持续时间可能长达5万年。在布伦斯纪古地磁倾角测井中，虽然有4个层位记录到浅层正倾角，但没有记录到其他反转事件。
Palaeomagnetic and palaeontological studies on samples withdrawn from a 250-m-long unorientated core from Reggio di Calabria, Italy (38°N, 16°E) are described. The lower 200 m of core penetrated off-shore clays and visual examination of the split sections of core indicated no obvious breaks in deposition. After alternating field demagnetization in 200 Oe the palaeomagnetic inclination log shows the Brunhes/Matuyama boundary at 110 m below which the Jaramillo and Olduvai Events within the Matuyama Epoch are identified. This interpretation of the magnetostratigraphy is supported by palaeontological evidence. The rate of accumulation of clay is estimated to have ranged between about 60 and 190 mm/kyr with an overall average through the Matuyama Epoch of about 90 mm/kyr. Assuming that this average rate continued through the Brunhes Epoch, the age of the top of the clay unit is estimated to be about 90,000 yr B.P. About 5 m from the unconformable top surface of the clay, a split sequence of reversed inclinations is interpreted as a record of the Blake Event, and the overall average deposition rate implies that its duration may have been as long as 50,000 yr. No other reversed event is recorded by the palaeomagnetic inclination log through the Brunhes Epoch, though there are four horizons where shallow positive inclinations are recorded.