VARIATIONS OF RATIO OF87Sr/86Sr IN SEAWATER WITH TIME:IMPLICATIONS FOR SEA LEVEL CHANGES AND GLOBAL CORRELATION
Received date: 1999-08-30
Revised date: 2000-05-08
Online published: 2000-12-01
Strontium(Sr) is one of the most sensitive indicators to seawater. It has been widely exploited both in terms of its concentration and particularly in its isotope, which has been used to investigating ancient sea level fluctuations. Appreciable progresses have been achieved in recent years, but problems still remained with the seawater87Sr/86Sr curve construction for the purpose of global correlation. It is shown that the variations of 87Sr/86Sr throughout the Phanerozoic are related to the sea level changes. High-frequence(2.0 Ma) fluctuations in seawater 87Sr/86Sr consistent with third-order sequence. These changes are controlled by Sr sources of the seawater. There are two main Sr sources, one is“the continental Sr”with a high 87Sr/86Sr, which is input to seawater by flux, the other one is“the oceanic Sr”with a low 87Sr/86Sr, which is got into seawater directly by hydrothermal circulation through seafloor. Conodont is the idea sample for the studies because of its precise stratigraphic age and high Sr concentrations as well as relatively resistant to digenetic alternation. The 87Sr/86Sr curve of seawater constructed by using conodont is the best standard for global correlation. China possesses some unique geological records, such as the continuous sedimentation at the Permian/Triassic boundary, which is very helpful to supplement the gap in the87Sr/86Sr curve constructed for seawater from Permian to Jurassic by R. B. Koepnicket al(1998) on the basis of Burkeet al(1982).
Key words： Strontium isotope; Sea level change; Global correlation; Conodont.
LI Rong-xi,WEI Jia-yong,YAN Wei-dong,GUO Qing-jun . VARIATIONS OF RATIO OF87Sr/86Sr IN SEAWATER WITH TIME:IMPLICATIONS FOR SEA LEVEL CHANGES AND GLOBAL CORRELATION[J]. Advances in Earth Science, 2000 , 15(6) : 729 -733 . DOI: 10.11867/j.issn.1001-8166.2000.06.0729
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