Phanerozoic Sea Floor Spreading Curve

Sea floor spreading rates over the past 180 my.

Phanerozoic sea floor spreading curve. 3 cannot be totally ascribed to permanent growth of ice sheets 26. 3 cannot be totally ascribed to permanent growth of ice. The configuration of the curve appears to be strongly influenced by the history of both plate interactions and seafloor spreading throughout the phanerozoic. An aragonite sea is the alternate seawater chemistry in which aragonite and high magnesium calcite are the primary inorganic carbonate precipitates.

Light green boxes indicate times of spreading rate increases on various ocean ridges 57. Comparison of phanerozoic backstripped eustatic estimates of this. The curve provides a basis for dating many marine carbonate evaporite and phosphate samples. Sea floor spreading rates over the past 180 my.

Our record implies a modest decrease in the rate of ocean crust production because the long term eustatic fall of 70 to 100 m since the early eocene fig. The kill curve shows that a typical species risk of extinction varies greatly with most time intervals being characterized by very low risk. Using new sea floor age data rowley suggested that there have been no changes in sea floor spreading rates over the past 180 my. 3 cannot be totally ascribed to permanent growth of ice sheets 26.

The early paleozoic and the middle to late mesozoic oceans were predominantly calcite seas whereas the middle paleozoic through the. Therefore the largest correction to the phanerozoic 87 sr 86 sr curve mcarthur et al 2012 would still be made for the permo triassic. The data suggest that seawater had. Our record implies a modest decrease in the rate of ocean crust production because the long term eustatic fall of 70 to 100 m since the early eocene fig.

Systematic changes in the chemistry of evaporated seawater contained in primary fluid inclusions in marine halites indicate that seawater chemistry has fluctuated during the phanerozoic. The fluctuations are in phase with oscillations in seafloor spreading rates volcanism global sea level and the primary mineralogies of marine limestones and evaporites. Although spreading rate is a principal forcing function in current geochemical cycling models berner and kothavala 2001 hansen and wallmann 2003 the magnitude of variation in this term based on the relationship between seafloor age and area has also been a matter of some debate parsons 1982 rowley 2002 demicco 2004. Heavy black line is the long term fit to our backstripped curve 23.

A calcite sea is one in which low magnesium calcite is the primary inorganic marine calcium carbonate precipitate. A kill curve for phanerozoic species is developed from an analysis of the stratigraphic ranges of 17 621 genera as compiled by sepkoski.