Sr Isotopes Across the KTB

The input of Sr required to account for the observed enhancement in 87Sr/86Sr ratio across the KTB can be determined by mass balance of the isotopes of Sr. Assuming the mid-ocean ridge (MOR) flux and isotopic ratio of Sr were unchanged, the total oceanic input of Sr at the KTB is described by the equation 

Before considering continental weathering further, we briefly discuss melt rock as a potential source of Sr. Chicxulub melt rock from a depth of 1.4 km below the center of the crater has a Sr concentration of 300 ppm and an isotopic ratio of 0.709 [20], with the result that 3 x 1015 moles Sr would be required to 

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