Extrapolating the Original Positions of Removed Onlap-Offlap Points Using a Piecewise-Constructed Model of Effective Stratal Thickness
-
摘要: 地层超覆点的迁移是层序地层分析和海平面变化曲线编制的重要依据。受构造抬升、海平面下降或二者共同作用影响,地层超覆点在沉积后常被剥蚀。如何恢复其原始沉积时的位置,至今尚无定量方法提出。基于地层厚度自盆地边缘向盆地中心依次增大,或先增大、后减小的分布特点,采用指数与线性相结合的分段函数模型,利用未剥蚀区地层厚度数据拟合外推恢复原始地层超覆点位置。该方法适用于被动大陆边缘、大型三角洲沉积区及坳陷型盆地,应用于巽他陆架晚新生代地层分析,取得满意效果.Abstract: The shift of onlap-of flap points is a critical factor in sequence stratigraphic analysis and charting sea level curves.Onlap-off lap points, however, are easily removed due to tectonic uplift, eustatic sea level fall, and so on.How to recover the original positions of removed onlap and of flap points has still been a pending problem.In this paper, we presented a piecew ise-const ructed function model to depict the lateral changes of stratal thickness along a dip section.It is assumed that the thickness of a stratum decreases exponentially from its maximum tow ards basin margin, and thins linearly on areas adjacent to the onlap-offlap points.Using this model, the positions of removed onlap and of flap points can be extrapolated by fitting the thickness data in non-removal areas.This approach is used in the study of the Pliocene to Pleistocene strata on the no rthern Sunda Shelf, South China Sea, and the result sare to our satisfaction.
-
[1] Vail P R, Mitchum R M Jr, Todd R G, et al. Seismic stratigraphy and global changes of sea level[A]. In: Payton C E ed. Seismic Stratigraphy-Applications to Hydrocarbon Exploration[C]. AAPG Memoir 26, 1977. 49～212 [2] Vail P R, Hardenbol J, Todd R G. Jurassic unconformities, chronostratigraphy and sea-level changes from seismic stratigraphy and biostratigraphy[A]. In: Schlee J S ed. Interregional unconformities and hydrocarbon accumulation[C]. AAPG Memoir 36, 1984. 129～144 [3] Haq B U, Hardenbol J, Vail P R. Chronology of fluctuating sea levels since the Triassic (250 million years ago to present)[J]. Science, 1987, 235: 1156～1167 [4] 钟广法.巽他陆架晚新生代地震超覆层序与海平面变化研究[D].上海:同济大学海洋与地球科学学院,2002[Zhong G. Late Cenozoic onlap-offlap sequences and sea level changes on the northern Sunda Shelf, South China Sea [D].Shanghai:School of Ocean and Earth Science,Tongji University,2000 ] [5] 徐怀大,樊太亮,韩革华,等.新疆塔里木盆地层序地层特征[M].北京:地质出版社,1997.192～199[Xu H, Fan T,Han G, et al. Sequence stratigraphy in the Tarim Basin, Xinjiang Uigur Autonomous Region, China[M]. Beijing:Geological Publishing House, 1997.192～199] [6] Emery D, Myers K J. Sequence stratigraphy[M]. Oxford: Blackwell Science Ltd, 1996. 1～297 [7] 汪品先.古环境研究[A].见:金性春,周祖翼,汪品先编.大洋钻探与中国地球科学[C].上海:同济大学出版社,1995.145～148[Wang P. Paleo-environmental research[A]. In: Jin X, Zhou Z, Wang P. Ocean drilling program and earth sciences in China[C]. Shanghai: Tongji University Press, 1995. 145～148] -
点击查看大图
计量
- 文章访问数: 445
- HTML全文浏览量: 6
- PDF下载量: 387
- 被引次数: 0
下载:
