نتایج جستجو برای: petrography
تعداد نتایج: 1284 فیلتر نتایج به سال:
Abrupt first-order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western Ireland during the 8200-year event (the major cooling episode 8200 years before the present) are interpreted as responses to a drier climate lasting about 37 years. Both shifts are centered on 8330 +/- 80 years before the present, coinciding with a large oxygen isotope anomaly and a c...
Examination of piston cores and, particularly, sediments collected by the Deep Sea Drilling Project has shown that authigenic dolomite occurs in a wide range of sedimentary associations. While the trace to a small percentage of dolomite often encountered in pelagic carbonate sequences may be a result of authigenesis under "normal" deep-sea conditions, the few studies to date seem to indicate th...
Petrographic evidence shows that pottery exchange between the Olmec and their neighbors was two-way.
Petrographic thin sections of pottery from five Formative Mexican archaeological sites show that exchanges of vessels between highland and lowland chiefly centers were reciprocal, or two-way. These analyses contradict recent claims that the Gulf Coast was the sole source of pottery carved with iconographic motifs. Those claims were based on neutron activation, which, by relying on chemical elem...
Introduction: Dhofar 1428 is a lunar feldspathic breccia found in 2006. Bunch et al. [1] briefly described mineral chemistry of Dhofar 1428. Korotev and Zeigler [2] analyzed its bulk FeO and Sm compositions. Here, we report such detailed data for Dhofar 1428. Results and Discussion: Dhofar 1428 has a distinct breccia texture with numerous fragments of rock, mineral, and glass all welded by a gl...
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