The discharge of fluid–particle mixture tailings can cause serious disturbance to the marine environment in deep-sea mining of polymetallic nodules. Unrecovered nodule fines are one of the key components of the tailings, but little information has been gained on their properties. Here, we report major, trace, and rare earth element compositions of <63 μm particles produced by the experimental degradation of two types of polymetallic nodules from the Clarion–Clipperton Zone. Compared to the bulk nodules, the fines produced are enriched in Al, K, and Fe and depleted in Mn, Co, Ni, As, Mo, and Cd. The deviation from the bulk composition of original nodules is particularly pronounced in the finer fraction of particles. With X-ray diffraction patterns showing a general increase in silicate and aluminosilicates in the fines, the observed trends indicate a significant contribution of sediment particles released from the pores and cracks of nodules. Not only the amount but also the composition of nodule fines is expected to significantly differ depending on the minimum recovery size of particles at the mining vessel.

The Intertropical Convergence Zone (ITCZ) is a band of vigorous convection and high precipitation formed by the confluence of southeasterly and northeasterly trade winds, and acts as a barrier to cross‐equatorial dust transport. We investigate the provenance of dust in the surface sediments of 16 cores collected along a 131.5°W transect from the equator to 16°N in the central Pacific. The results reveal well‐defined Asian dust signals north of 7°N and mixed Asian–South American source signals south of 6°N. We propose the southernmost latitude with an intact Asian source signal (7°N) as the present‐day mean ITCZ position in terms of dust provenance in the central Pacific. This geochemically defined mean ITCZ position reflects differences in thermal and dust fluxes between hemispheres and can be used as a reference for quantitatively assessing ITCZ displacement in the sedimentary down‐core records back to ca. 14 Ma.

To test the previous hypothesis that upper Paleozoic sediments in the eastern Sino-Korean Block were mostly derived from the paleo-orogen located to the east, we compared published and new U–Pb age data of detrital zircons from Pennsylvanian strata distributed in the Sino-Korean Block (SKB). The age distributions of detrital zircons from different localities of Pennsylvanian strata in North China reflect varying contributions from the Inner Mongolia Paleo-uplift in the north and the Central China Orogenic Belt in the south. The supply of detritus from the northern source to distant areas, however, appears to have been limited during the Pennsylvanian times. The age distributions of detrital zircons from Korean Pennsylvanian strata located in the east of the SKB are characterized by a dense cluster of 1.84–1.90 Ga and differ from those of North China. The Korean age characteristic is best explained by strong influences of the detritus derived from the Paleoproterozoic Yeongnam Massif in southeastern Korea. Along with the significant number of zircons that record syn- to near-depositional magmatic activities, this observation supports the hypothesis of the existence of an active continental margin setting in the east of the SKB.

영남육괴 서부 광주광역시-장성군과 화순-보성군일대에 분포하는 고원생대 다이아텍사이트 혼성암에 대한 저어콘 U-Pb 연령측정을 토대로 영남육괴 고원생대 퇴적기원 변성암 모암의 퇴적시기에 대해 검토하였다. 광주광역시-장성군 일대에 분포하는 다이아텍사이트 혼성암의 저어콘 상속핵 연령은 약 2478 Ma의 연령 피크가 두드러지며 퇴적시기 상한은 약 2085 Ma로 추정된다. 이와 달리 화순-보성군 일대에 분포하는 다이아텍사이트 혼성암에서는 약 2506 Ma, 2338 Ma, 2205 Ma, 1985 Ma, 1945 Ma의 다양한 저어콘 상속핵 연령 피크가 나타나며 퇴적시기 상한은 약 1971 Ma로 추정된다. 두 지역 모두에서 퇴적시기 하한은 저어콘 외연부가 지시하는 변성연대를 토대로 1880 Ma 내외로 제한된다. 광주광역시-장성군지역에 분포하는 다이아텍사이트 혼성암의 모암은 퇴적시기와 저어콘 연령 특성이 율리층군, 원남층군 등 영남육괴 동부에 분포하는 고원생대 지층들과 유사하며 서로 대비될 가능성이 있다. 반면 화순-보성군 일대에 분포하는 다이아텍사이트 혼성암 모암의 퇴적시기는 영남육괴 동부에 분포하는 고원생대 지층들보다 후기에 해당하며 저어콘 연령 특성 역시 구별된다. 이는 영남육괴 서부 일부 지역에 기존에 논의되지 않았던 새로운 고원생대 지층의 분포 가능성을 의미한다.