Testing an arc volcanism - climate link in a high-latitude Plio-Pleistocene marine tephra archive at ODP Site 882 (northwest Pacific)

这个项目探索高纬度的火山活动。据推测，火山活动与地球气候的周期性变化有关，特别是与最近~ 260万年冰期/间冰期陆地冰盖的生长和萎缩有关。作为多国海洋钻探计划（ODP）的一部分，将研究通过海洋钻探回收的沉积物岩心。在这些岩心中，将测量堪察加半岛和阿留申群岛火山产生的火山灰层的数量和组成。目前的数据显示，在260万年前地球最近的冰期开始时，火山活动急剧增加。这种增加之后是火山爆发频率的周期性变化。这项研究将表明，在这260万年的时间里，这些火山周期是否与轨道驱动的气候周期同步，如果地球的火山活动与全球气候周期有关，这是可以预料到的。该项目将由来自美国、澳大利亚和墨西哥的国际研究小组进行，其中包括火成岩地球化学家和气候科学家。这个小组由一位残疾女科学家领导。该项目为研究生和本科生培训提供了机会，为俄罗斯和德国从事互补项目的同事提供了联系机会，并为K-12教师和学生以及公众提供了机会。该项目将验证冰川-火山假说，即~2.6 Ma海洋沉降灰床频率的增加及其随后在北太平洋的波动是否与更新世冰旋回有因果关系。这将通过在ODP站点882 （Leg 145）的两个孔中钻取的上新世-更新世火山灰床记录来完成，这些记录通过先进的活塞取心（APC）技术100%恢复，并且包含了丰富的时间精确的上新世晚期到最近的火山灰床记录，这些记录来自高纬度火山弧，全球冰川循环的影响最强。研究小组将获得882号站点火山灰层的修订后的详细岩石地层描述，并通过额外的主要和微量元素分析（包括Cl、Pb和Nd同位素比率）来补充现有的成分数据，以测试(i)米兰科维奇期是否存在于火山灰层系列中；（ii）在中更新世过渡时期（~0.7 ~ 1.1 Ma）有明显的灰层旋回性变化；(3)火山灰层旋回性受不同弧源物源的影响；(4)岩浆对火山灰床旋回有控制作用。这项研究可以回答海洋灰床系列中记录的爆炸性弧火山活动的速度是由冰川作用决定的，还是这些信号在影响爆炸性弧火山活动时间的其他过程中很大程度上丢失了。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project explores high latitude volcanic activity. It is hypothesized that the volcanic activity is linked to cyclic variations in Earth’s climate, especially the growth and shrinking of terrestrial ice sheets during the glacial / interglacial cycles of the last ~2.6 million years. Sediment cores will be studied that were recovered by ocean drilling as part of the multi-national Ocean Drilling Program (ODP). In those cores the number and composition of ash layers produced by the volcanoes of Kamchatka Peninsula and the Aleutian Islands will be measured. Current data show a strong increase of volcanic activity at the beginning of the Earth’s most recent glacial period, 2.6 million years ago. That increase was followed by periodic changes in how often volcanoes erupt. This study will show whether those volcanic cycles are timed with orbitally-driven climate cycles through that 2.6 million year period, which would be expected if Earth’s volcanism was linked to global climate cycles. The project will be carried out by international team of researchers from the United States, Australia and Mexico that includes igneous geochemists and climate scientists. The team is led by a women scientist with a disability. The project provides opportunities for graduate and undergraduate student training, for connecting with colleagues in Russia and Germany who work on complementary projects, and for outreach to K-12 teachers and students and to the general public. The proposed project will test the glacio-volcano hypothesis whether the increase in marine fallout ash bed frequency at ~2.6 Ma and its subsequent fluctuation in the North Pacific is causally related to the Pleistocene ice cycles. This will be done by means of the Plio-Pleistocene ash bed record drilled in two holes at ODP Site 882 (Leg 145), which are 100% recovered by advanced piston coring (APC)-techniques and that contain a rich and time-precise, late Pliocene to Recent ash bed record from high-latitude volcanic arcs where the effects of global glaciation cycles are strongest. The team will obtain a revised, detailed lithostratigraphic description of the Site 882 ash beds, and augment the existing compositional data by additional major and trace element analyses, including Cl, and Pb and Nd isotope ratios in order to test whether (i) Milankovitch periods are present in the ash bed series; (ii) there is a tell-tale change in ash bed cyclicity across the Mid-Pleistocene Transition (~0.7-1.1 Ma); (iii) ash bed cyclicity is affected by provenance from different arcs; and (iv) there is a magmatic control on ash bed cyclicity. The study could provide an answer to whether tempos of explosive arc volcanism as recorded in the marine ash bed series are paced by glaciation, or whether such signals are largely lost in the maze of other processes that influence the timing of explosive arc volcanism.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.