A revised sea-level curve for the early Jurassic

Abstract

A comparison is undertaken of three different methods of eustatic sea-level analysis: (1) shallowing and deepening/transgressive events inferred from the facies sequence, (2)changes through time in the areal spread of epicontinental seas,(3) seismic stratigraphy. The results of these methods are compared, mainly with reference to the Lower Jurassic. New data are brought forward from several continents in a stage-by-stage study and it is concluded that theLias was characterized by interrupted sea-level rise with no major regressions.Both the transgressions and regressions were relatively rapid,with the major transgressions associated with widespread anoxic bottom waters.Estimates of the net amount of sea-level rise through early Jurassic time range from ∼75 m to ∼110 m.