Mineralisation from hot fluid flows in the sandstone-type uranium deposit in the Kailu Basin, Northeast China

Abstract

The Qianjiadian-Baixingtu uranium deposit (QBUD) is in the post-Jurassic extensional Kailu basin of northeast China. There is a well-developed fault system in and adjacent to the deposit, and uranium mineralisation appears controlled by faults F 1, F 2, and F 3. Lots of diabase (dolerite) intrusions related to regional faults are extensive throughout the QBUD. The ellipsoidal and lenticular mineralised bodies in the QBUD conflict with the interlayered oxidation genesis. Furthermore, heat from the diabase intrusions not only makes the wall rocks hard, but plenty of new cement minerals are precipitated from hot fluid flow (HFF). The clastic grains in the host sandstone are strongly altered by HFF. Carbonate cements involves calcite, ankerite, and Fe-rich dolomite. There are three inclusion temperature peaks: ∼90°C, 110-120°C, and 140-150°C, and three ranges of inclusion salinity: 5.

Petrogenetic Constraints of Early Cenozoic Mafic Rocks in the Southwest Songliao Basin, NE China: Implications for the Genesis of Sandstone-Hosted Qianjiadian Uranium Deposits

“…Nevertheless, recent EPMA chemical dating indicated that most of the U mineralization ages are younger than 40 Ma, with a peak in the Miocene or later (<20 Ma) [36], which is in good agreement with the tectonic evolution model proposed in the previous paragraph. Moreover, these ages postdate the emplacement of the mafic rocks, hence, arguing against the model proposed by Nie et al [34] involving mantle-derived CO 2 -rich hydrothermal fluids in the U ore genesis. with the tectonic evolution model proposed in the previous paragraph.…”

“…Eocene mafic rocks are widespread in sandstones of the Yaojia Formation hosting the U mineralization in the Qianjiadian deposit (Figure 1). Previous studies proposed that the intrusion of these mafic rocks triggered subsequent circulation of mantle-derived CO 2 -rich hydrothermal fluids, which could have been responsible for U leaching from the surrounding sandstones [34]. In addition, it has also been proposed that the genesis of the U mineralization in the Qianjiadian area was controlled by BSR processes within organic matter (OM)-bearing sandstones [28][29][30][31][32][33].…”

“…Several studies were conducted on the micromorphological observations, in situ sulfur isotope analysis of pyrites, and carbon isotope composition of calcite cement, emphasizing the role of bacterial sulphate reduction (BSR) in the genesis of the U mineralization in the Qianjiadian area [28][29][30][31][32][33]. Nevertheless, the tabular U ore bodies in the Qianjiadian deposit are spatially associated with secondary reduced gray sandstones or bleached white sandstones [34] ( Figure 2) together with the widely distributed mafic rocks [17], which significantly differ from the two predominant models of redox front sandstone-hosted U deposits presented in [33]. In addition, detailed petrographic studies performed on carbonaceous debris from this deposit showed significant increase of the vitrinite reflectance, suggesting that the U mineralization is spatially associated with the alteration halo of the diabase dikes [20].…”

“…[35]). (c) Spatial distribution of the interstratified oxidation and mafic rocks in the Qianjiadian uranium deposit, modified after [34] and [19]. [35]).…”

“…[35]). (c) Spatial distribution of the interstratified oxidation and mafic rocks in the Qianjiadian uranium deposit, modified after [19,34]. Moreover, the apatite and zircon fission-track data of the Baixingtu ore deposits recorded two distinct stages of rapid cooling after the Late Cretaceous, with stage I at ~80-50 Ma and stage II at Moreover, the apatite and zircon fission-track data of the Baixingtu ore deposits recorded two distinct stages of rapid cooling after the Late Cretaceous, with stage I at~80-50 Ma and stage II at 40-10 Ma, respectively [5].…”