Re-appearance of precipitated aragonite crystal fans as evidence for expansion of oceanic dissolved inorganic carbon reservoir in the aftermath of the Lomagundi-Jatuli Event

The initial accumulation of atmospheric oxygen is marked by the unprecedented positive δ13Ccarb excursions of the Lomagundi-Jatuli Event (LJE) and records an interval of abnormal O2 production through elevated rates of organic carbon burial. Emerging evidence suggests that the post-LJE atmosphere-ocean system might have suffered a significant deoxygenation. These dynamic perturbations in the oceanic redox state and biogeochemical cycles would have led to fundamental changes in carbonate precipitation dynamics. Here, we report the discovery of centimeter-sized crystal fans in the post-LJE Huaiyincun Formation, Hutuo Supergroup in the North China Craton. The hexagonal cross-sections and square terminations suggest that these fan-like dolomitic structures were originally aragonite crystal fans (ACF). Variations of stromatolite morphology and frequent occurrences of storm-related deposits in the Huaiyincun Formation point to repeated cycles of sea level changes. The bedding-parallel distribution of the ACF and the homogeneous δ13C values of the ACF-bearing dolostones are consistent with a primary depositional origin for the ACF. An updated compilation of published records of ACF throughout geological history highlights a clear absence of ACF from the initiation of the Paleoproterozoic Great Oxidation Event until the end of the LJE, and a global reappearance of ACF in the post-LJE late Paleoproterozoic. We propose that the reappearance of ACF is in agreement with the expansion of the oceanic dissolved inorganic carbon reservoir. At the same time, consumption of dissolved oxygen during the oxidation of organic matter might have been stimulated by ferruginous deep seawater, facilitating the formation of Huiayincun ACF

Bulk compositions of the Chang’E-5 lunar soil: Insights into chemical homogeneity, exotic addition, and origin of landing site basalts

Lunar soil is a fine mixture of local rocks and exotic components. The bulk-rock chemical composition of the newly returned Chang’E-5 (CE-5) lunar soil was studied to understand its chemical homogeneity, exotic additions, and origin of landing site basalts. Concentrations of 48 major and trace elements, including many low-concentration volatile and siderophile elements, of two batches of the scooped CE-5 soil samples were simultaneously obtained by inductively coupled plasma mass spectrometry (ICP-MS) with minimal sample consumption. Their major and trace elemental compositions (except for Ni) are uniform at milligram levels (2–4 mg), matching measured compositions of basaltic glasses and estimates based on mineral modal abundances of basaltic fragments. This result indicates that the exotic highland and KREEP (K, rare earth elements, and P-rich) materials are very low (<5%) and the bulk chemical composition (except for Ni) of the CE-5 soil can be used to represent the underlying mare basalt. The elevated Ni concentrations reflect the addition of about 1 wt% meteoritic materials, which would not influence the other bulk composition except for some highly siderophile trace elements such as Ir. The CE-5 soil, which is overall the same as the underlying basalt in composition, displays low Mg# (34), high FeO (22.7 wt%), intermediate TiO2 (5.12 wt%), and high Th (5.14 µg/g) concentrations. The composition is distinct from basalts and soils returned by the Apollo and Luna missions, however, the depletion of volatile or siderophile elements such as K, Rb, Mo, and W in their mantle sources is comparable. The incompatible lithophile trace element concentrations (e.g., Ba, Rb, Th, U, Nb, Ta, Zr, Hf, and REE) of the CE-5 basalts are moderately high and their pattern mimics high-K KREEP. The pattern of these trace elements with K, Th, U, Nb, and Ta anomalies of the CE-5 basalts cannot be explained by the partial melting and crystallization of olivine, pyroxene, and plagioclase. Thus, the mantle source of the CE-5 landing site mare basalt could have contained KREEP components, likely as trapped interstitial melts. To reconcile these observations with the initial unradiogenic Sr and radiogenic Nd isotopic compositions of the CE-5 basalts, clinopyroxene characterized by low Rb/Sr and high Sm/Nd ratios could be one of the main minerals in the KREEP-bearing mantle source. Consequently, we propose that the CE-5 landing site mare basalts very likely originated from partial melting of a shallow and clinopyroxene-rich (relative to olivine and orthopyroxene) upper mantle cumulate with a small fraction (about 1–1.5 %) of KREEP-like materials

A Novel Sliding Window PCA-IPF based Steady-State Detection Framework and Its Industrial Application

In industrial processes, it is of great significance to carry out steady-state detection (SSD) for effective system modeling, operation optimization, performance evaluation and process monitoring. Traditional SSD approaches often need to identify process state for each variable and obtain a composite index with sliding window technique, which ignores the variable correlations and is time consuming. Moreover, they can only provide the state of each whole window that slides along data series. To deal with these problems, a novel sliding window PCA-IPF (principal component analysis-improved polynomial fitting) based method is proposed for steady-state detection. In the proposed framework, principal component analysis is first used to eliminate the data correlations and variable noises. Then, the size of sliding window is automatically determined by the data series of the first principal component. After that, SSD is carried out for each selected principal component by 2nd-order improved polynomial fitting. At last, the overall process state is determined by the weighted combination of the SSD results of selected principal components, in which the weight of each principal component is determined by the its corresponding contribution of variance. The effectiveness and flexibility of the proposed SSD framework is validated on an industrial hydrocracking process.Peer reviewe

Experimental data about Tremolite

&lt;p&gt;Experimental data about Tremolite&lt;/p&gt

Metallogenic prediction of copper polymetallic deposit in the Yueyashan-Laodonggou area, Beishan Ore Belt

The Yueyashan-Laodonggou area in the Inner Mongolia is located in the southeast of Beishan Ore Belt.Previous prospecting work in the area focuses on gold, tungsten and other minerals, wheras it rarely involved copper-related deposits.Based on the field geological survey, in combination with extraction and comprehensive analysis of indoor multivariate prospecting information, we systematically studied the geological characteristics, prospecting model and comprehensive prospecting information of typical copper polymetallic deposits in this area, and thus finally carried out metallogenic prediction.The copper in the area mostly occurs with iron, lead and zinc, and the deposits are controlled by carbonate, Paleozoic intermediate-felsicplutons and NW-NWW faults, thus can be classified as skarn-type copper polymetallic deposits.The places with NW-NWW faults, high magnetic anomalies and Cu-Pb-Zn geochemical anomalies are favorable prospecting area for such deposits.Hereby, four prediction areas (A1, A2, B1, C1) have been delineated, and high-quality mineralization and alteration are observed in two of them(A1, A2) by field verification, which points out the direction for the next-stage work in this area