Article Abstract:
Analysis of strontium (Sr) isotope data confirms that the Sr curve should be placed far underneath the Cretaceous/Tertiary boundary. Moreover, the Sr isotope anomaly is not located at that boundary as some researchers believe. The assertions that error in locating the Upper-Lower Maastrichtian boundary and unrecognized faulting both invalidated calculations of marine Sr isotope evolution were likewise wrong. In fact, a recent zonation derived from nannofossil data supported the placement of the Upper/Lower Maastrichtian boundary at around 95 to 150 meters.
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Article Abstract:
Recent research has maintained that the oxygen isotope composition of pre-Carboniferous marine mineral samples is lower than that observed in post-Devonian samples. Two explanations have been offered of this alleged fact: that it reflects warmer pre-Carboniferous oceans relative to modern oceans or that pre-Carboniferous oceans were depleted in oxygen-18. However, new findings in normal, shallow-marine limestones show that the temperature and oxygen isotope composition of the pre-Carboniferous oceans was similar to that of modern oceans.
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Article Abstract:
A new study by S.C. Clemens and colleagues reveals a surprising glacial link to strontium isotope ratios in the ocean. These ratios indicate the relative sources of ocean material: continental (via rivers) and hydrothermal (upwelling of the ocean floor). The data are within the margin of error of the researchers' equipment, so some dispute the validity of their statistical results. One explanation may be that glacial changes in ocean levels influence hydrothermal flux.
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