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

该项目探索高纬度火山活动。据推测，火山活动与地球气候的周期性变化有关，特别是与过去约260万年的冰川/间冰期周期中陆地冰盖的增长和缩小有关。作为多国海洋钻探计划的一部分，将对通过海洋钻探回收的沉积物岩芯进行研究。在这些岩芯中，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成分。目前的数据显示，在260万年前地球最近的冰川期开始时，火山活动强劲增加。在这一增长之后，火山喷发的频率也出现了周期性的变化。这项研究将表明，这些火山周期是否与轨道驱动的气候周期在260万年期间计时，如果地球的火山活动与全球气候周期有关，预计会出现这种情况。该项目将由来自美国、澳大利亚和墨西哥的国际研究团队实施，其中包括火成岩地球化学家和气候科学家。该团队由一位残疾女科学家领导。该项目为研究生和本科生的培训提供了机会，为在俄罗斯和德国从事补充项目的同事提供了联系，并与K-12教师和学生以及普通公众进行了接触。该项目将检验冰川-火山假说是否与更新世冰旋回有关，约2.6 Ma的海洋尘埃灰床频率的增加及其在北太平洋的波动是否与更新世冰旋回有关。这将通过在ODP882(第145段)的两个孔中钻取的上更新世火山灰床记录来完成，这些记录由先进的活塞取心(APC)技术100%恢复，包含了丰富的、时间精确的上新世晚期火山灰床记录，这些记录来自高纬度火山弧，那里是全球冰川旋回影响最强烈的地方。该小组将获得修订后的882个火山灰层的详细岩石地层描述，并通过额外的主要和微量元素分析来补充现有的成分数据，包括氯、铅和钕同位素比值，以便测试(I)火山灰床系列中是否存在米兰科维奇周期；(Ii)中更新世过渡时期(约0.7-1.1 Ma)火山灰床旋回性存在明显的变化；(Iii)火山灰床旋回性受到来自不同弧的物源的影响；以及(Iv)火山灰床旋回性是否受到岩浆控制。这项研究可能会回答海洋火山灰床系列中记录的爆炸弧形火山活动的节奏是否受到冰川的影响，或者这种信号是否在影响爆炸弧形火山爆发时间的其他过程的迷宫中大部分消失了。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.