Genesis for Rare Earth Elements Enrichment in the Permian Manganese Deposits in Zunyi, Guizhou Province, SW China

Abstract

The Zunyi manganese deposits, which formed during the Middle to Late Permian period and are located in northern Guizhou and adjacent areas, are the core area of a series of large‐medium scale manganese enrichment minerogenesis in the southern margin and interior of the Yangtze platform, Southern China. This study reports the universal enrichment of rare earth elements (REEs) in Zunyi manganese deposits and examines the enrichment characteristics, metallogenic environment and genesis of REEs. The manganese ore bodies present stratiform or stratoid in shape, hosted in the silicon–mud–limestones of the Late Permian Maokou Formation. The manganese ores generally present lamellar, massive, banded and brecciated structures, and mainly consist of rhodochrosite, ropperite, tetalite, capillitite, as well as contains paragenetic gangue minerals including pyrite, chalcopyrite, rutile, barite, tuffaceous clay rock, etc. The manganese ores have higher ΣREE contents range from 158 to 1138.9 ppm (average 509.54 ppm). In addition, the ΣREE contents of tuffaceous clay rock in ore beds vary from 1032.2 to 1824.5 ppm (average 1396.42 ppm). The REEs from manganese deposits are characterized by La, Ce, Nd and Y enriched, and existing in the form of independent minerals (e.g., monazite and xenotime), indicating Zunyi manganese deposits enriched in light rare earth elements (LREE). The Ceanom ratios (average –0.13) and lithofacies and paleogeography characteristics indicate that Zunyi manganese deposits were formed in a weak oxidation‐reduction environment. The (La/Yb)ch, Y/Ho, (La/Nd)N, (Dy/Yb)N, Ce/Ce* and Eu/Eu* values of samples from the Zunyi manganese deposits are 5.53–56.92, 18–39, 1.42–3.15, 0.55–2.20, 0.21–1.76 and 0.48–0.86, respectively, indicating a hydrothermal origin for the manganese mineralization and REEs enrichment. The (δ13CV‐PDB (−0.54 to −18.1%) and (δ18OSMOW (21.6 to 26.0%) characteristics of manganese ores reveal a mixed source of magmatic and organic matter. Moreover, the manganese ore, tuffaceous clay rock and Emeishan basalt have extremely similar REE fractionation characteristic, suggesting REEs enrichment and manganese mineralization have been mainly origin from hydrothermal fluids.

Stratigraphy of the Guadalupian (Permian) siliceous deposits from central Guizhou of South China: Regional correlations with implications for carbonate productivity during the Middle Permian biocrisis

“…In addition, the silicified rocks differ from place to place in regard to the clast types, sizes, shapes and depositional successions. Xu et al (2020) recently measured the silicon isotopes and REE values of these massive silicified rocks and suggested that the observed brecciation and silicification resulted from hydrothermal migration along potential syndepositional faults during the stage of the ELIP.…”

Evaluation Methods and Indexes for Ultra‐deep Petroleum Reservoir Preservation with Case Studies

“…The dynamic matching relationship between source and caprock in well GS-1 is not ideal for reservoir formation. Due to the Lower Cambrian source rock being close to the middle belt of the Emeishan basalt eruption area (Xu et al, 2020), under high heat flow and temperature, it rapidly matured and generated hydrocarbons. The kerogen matured sharply and the vitrinite reflectance reached more than 3.5% by the end of the Early Permian, the hydrocarbon generating potential being exhausted.…”

Hydrocarbon Generation Characteristics of Source Rocks from Different Saline Environments in the Dongpu Depression, Bohai Bay Basin, China

“…Although the sampling wells already exist in their own sedimentary environments of different salinities, some trace elements of the samples used for the thermal simulation experiments have also been tested, aiming to ensure that the three samples unquestionably represent different salinities. As the element B and the ratios of B to Ga and Sr to Ba can effectively represent the paleosalinity, they are used to identify the salinity values of W18-5, H7-18 and CH9, the value of the paleosalinity specifically having a positive correlation with B, B/Ga and Sr/Ba (You et al, 2003;Xu et al, 2020). As shown in Table 4, all three indicators show that W18-5 has the highest salinity, followed by H7-18 and CH9.…”