Granularity and textural analysis as a proxy for extreme wave events in southeast coast of India

Journal of Earth system science

S G N Murthy2¹  C S Vijaya Lakshmi1²  Deshraj Trivedi1²  P Srinivasan2¹  Rajesh R Nair1² 

[1] Structural Engineering Research Centre, Chennai 600 113, India.$$;Department of Geology & Geophysics, Indian Institute of Technology, Kharagpur 721 302, India.$$

关键词: Extreme wave events;    grain size analysis;    tsunami deposits;    texture;    surges;    sorting.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Extreme wave events of 1000 and 1500 years (radiocarbon ages) have been recently reported in Mahabalipuram region, southeast coast of India. Subsequently, we carried out extensive sedimentological analysis in regions covering a total lateral coverage of 12 km with a new archeological site as the central portion of the study area. Twelve trenches in shore normal profiles exhibit landward thinning sequences as well as upward fining sequences confirming with the global signatures of extreme wave events. The sediment size ranges from fine-to-medium and moderately well sorted-to-well sorted, and exhibit positive skewness with platykurtic-to-leptokurtic nature. We now propose the abrupt winnowing or back and forth motion including unidirectional transport of these deposited sediments, which results in positive skewness. Textural analyses derived from scanning electron microscope studies (SEM) demonstrate the alteration produced, in the ilmenite mineral with vivid presence of pits and crescents with deformation observed on the surface due to extreme wave activities. This is further confirmed with the predominance of high-density mineral such as magnetite (5.2) and other heavy minerals in these deposits inferred the high-intensity of the reworking process of the beach shelf sediments.

【 授权许可】

Unknown