Distribution of shallow-water sediments founded in the records of deep-sea drilling and sea-level rise since the Jurassic period.

Hoshino (1991) argued that the sea-level in the Jurassic period was at the present depth of 6,000 m, and that the sealevel rise was caused by the uplift of the sea floor including the volcanic activity of flood basalts as well as the uplift of the crust after the Jurassic period. In order to provide evidence for Hoshino's sea-level rise theory, this paper investigates the sites where shallow-water sediments and volcanic rocks of subaerial eruption were found in the drilling records from DSDP to ODP. As a result, 256 sites were recovered with sediments and rocks indicating such shallow-water or land. Based on their distribution and assuming that they did not subsident we can estimate that the sea-level was about 6,000 m in the Late Jurassic period, 5,200 m in Barremian, 4,100 m at the end of Albian, 3,800 m in Early Eocene, 3,400 m in Late Oligocene, 3,400 m in Middle Miocene, and 3,000 m lower at the end of Miocene, or even lower in respectively. This supports the Hoshino's sea-level rise theory. However, the thickness of the coral reef limestone at each period suggests that the sea-level position at each period was lower than the past sea-level position estimated from the results of deep-sea drilling. Therefore, a sea-level rise curve was created by accumulating the amount of coastal onlap in the Haq’s curve and assuming that the sea-level was 3,000 m lower than the present sea-level at the end of Miocene epoch. According to the new sea-level rise curve proposed in this paper, the position of the sea-level at the end of the Jurassic period may have been considerably lower, about 12 km below present sea-level. In other words, the sea-level may have risen by 12 km since the Jurassic period. Based on the drilling records and the geological structure of each area, the deep-sea floor of the Atlantic and Indian Oceans is thought to have been composed of the Proterozoic and Hercynian basement rocks until the end of the Paleozoic Era, submerged by sea-level rise due to flood basalts since Triassic, and deepened by large-scale sea-level rise since Cretaceous. On the other hand, the base of the deep-sea floor of the Pacific Ocean is likely to be composed of the Archean basements, which were submerged more than 6,000 m by volcanic activity of basaltic lava of the Large Igneous Provinces (LIPs) mainly after the Late Jurassic period. [ABSTRACT FROM AUTHOR]