Sr and 87Sr/86Sr in rivers draining the Deccan Traps (India): Implications to weathering, Sr fluxes, and the marine 87Sr/86Sr record around K/T

摘要: The concentration of dissolved Sr and its 87Sr/86Sr has been measured in the headwaters Krishna River System west flowing Western Ghat rivers, all which have their drainage almost entirely Deccan Traps. follows that Ca Mg with Sr/Ca Sr/Mg ratios similar to basalts, suggesting these alkaline earths are released waters nearly congruently from basalts during chemical weathering. range 0.70614 0.70986, within reported for basalts. flux calculated data is ∼1.35 × 108 moles yr−1, ∼0.4% global riverine flux, same as proportion area covered by relative drainage. however, a factor ∼3 lower than Narmada-Tapti-Wainganga (NTW) rivers draining northern Deccan. This difference among various regions could be natural spatial/temporal variations and/or due supply NTW nonbasaltic sources. Model calculations on role emplacement weathering marine isotope evolution around KTB late Tertiary show can an important contributor decline periods. It shown account pre-KTB dip 87Sr/86Sr, requirement at time would several times contemporary 0.705–0.708. Considering was about thrice present rate may much higher early stages following eruption, such high fluxes seem feasible. disproportionately invoked explain decrease 187Os/188Os. also unradiogenic significant control long-term, ∼66 ∼55 Ma, 87Sr/86Sr.