期刊
MINERALS
卷 10, 期 4, 页码 -出版社
MDPI
DOI: 10.3390/min10040319
关键词
potassic rocks; sulfide; trace elements; Pb isotopes; lithosphere; Quaternary; Wudalianchi; Northeast China
资金
- RSF [18-77-10027]
- Heilongjiang Administration of Foreign Experts Affairs [D201800026, DWHE2018SH01, P192011009]
- Heilongjiang Academy of Sciences [DWHE2018SH01, DWHE2019SH01]
- Russian Science Foundation [18-77-10027] Funding Source: Russian Science Foundation
In the Wudalianchi volcanic field, eruptions started with low-Mg potassic lava flows 2.5-2.0 Ma ago and later changed to both low- and moderate-Mg potassic compositions. Volcanic rocks from the Molabushan and Longmenshan volcanoes record an unusually wide range of Pb abundances (from 3.7 ppm to 21 ppm relative to predominant range of 10-15 ppm). To determine the cause of these, we performed a comparative trace-element and Pb isotope study of rocks from these volcanoes and older lava flows. On a uranogenic lead diagram, older low-Mg lavas from lithospheric mantle sources plot on a secondary isochron with a slope corresponding to an age of 1.88 Ga. This contrasts with moderate-Mg volcanic rocks from the Molabushan cone, interpreted to have been derived from a recent convective mantle source, which define a flat linear pattern. Low-Mg rocks from the Molabushan flow have lead isotopic compositions that indicate mixed Gelaqiu and Molabu sources. Relative to rocks from the Molabushan cone, moderate-Mg lavas and slags from the East Longmenshan volcano have modified compositions characterized by Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as Pb-206/Pb-204, Pb-207/Pb-204, Pb-208/Pb-204, Ce/Pb, Th/Pb, and U/Pb ratios. We infer that the older Wudalianchi magmas were likely derived from a Paleoproterozoic lithospheric fragment, related to the evolved primordial mantle, and that later magmas were generated in the convecting mantle. These were influenced by segregation of small amounts of sulfides.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据