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The accretionary processes and the continental growth of the Altaids are still controversial. The Beishan orogen is situated in the southernmost Altaids and is an ideal tectonic site to address these issues. In this study, we report the results of new field-based lithological mapping and structural analysis on the Huaniushan complex in the Beishan orogen, which is composed of blocks of serpentinized ultramafic, gabbro, basalt, chert, limestone, and other rocks within a strongly deformed and cleaved matrix of sandstone and schist. Our new zircon U-Pb date reveal that a gabbro block formed at 504 ± 3 Ma. Our geochemical and isotopic data of gabbroic and basaltic blocks show that they are relics of the Mid-Ocean-Ridge (MORB)-type and Ocean-Island-Basalt (OIB)-type oceanic lithosphere, with high values of εNd(t) (+4.3–+14.5) and εHf(t) (+8.07–+17.74). The maximum depositional ages (MDAs) of two sandstone blocks were dated at 309 ± 5 Ma and 502 ± 11 Ma, respectively. U-Pb ages and Hf isotopes of detrital zircons from the matrix sandstones indicate that they were derived only from the Shuangyingshan–Huaniushan arc to the north. Accordingly, the Huaniushan complex was part of the Liuyuan accretionary complex that fringed the Huaniushan arc, and, therefore, formed by the northward subduction of the Liuyuan oceanic plate. Combined with the basalt yields zircon U-Pb age of 1,071 ± 5 Ma, we concluded that the Huaniushan complex has an age of 1,071 Ma to 309 Ma. Furthermore, the oceanic blocks and sedimentary matrix of the Liuyuan accretionary complex have an age of 1,071–270 Ma and 920–234 Ma, respectively, suggesting that the Liuyuan Ocean was still open at ca. 234 Ma. Thus, the studies reveal that the Liuyuan Ocean, a major branch of the Paleo-Asian Ocean, may have experienced a prolonged tectonic history, starting in the late Mesoproterozoic (1,071 Ma) and terminating later than the late Triassic (234 Ma), with a long subduction and development of a series of seamounts and/or plateaus emplaced into the Liuyuan accretionary complex.

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Atmospheric residue from Saudi Arabia (SZAR) was subjected to supercritical fluid extraction fractionation (SFEF) experiments. Four extractable subfractions (SFEF 1−4) and an unextractable end-cut were obtained. SFEF 1−4 were subjected to a hydrotreating (HDT) test in a mini-tubular reactor packed with commercial hydrodemetallization (HDM) and hydrodesulfurization (HDS) catalysts in order to determine the structural composition transformation of sulfur-containing compounds. Experiments were undertaken at a temperature of 360°C, a hydrogen pressure of 14.7 MPa, a liquid hour space velocity (LHSV) of 0.25 h −1 , and a H 2 /feed ratio of 650:1 (m 3 /m 3 ). The SFEF subfractions and their products were subjected to analysis of their sulfur and nitrogen contents, using an ANTEK 7000S analyzer, and their saturates, aromatics, resins, and asphaltenes (SARA) compositions were analyzed using open column liquid chromatography. The detailed molecular composition of sulfur heteroatom species was determined by methylation, followed by positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). In ESI FT-ICR analysis, the sulfur-containing compounds were characterized in terms of class, type (double bond equivalence, DBE), carbon number distribution, and relative abundance. According to the different number of sulfur atoms, sulfur-containing compounds can be divided into S 1 and S 2 class species. The results show that, depending on different transformation mechanisms, S 1 class species, which have less-aromatic cores, are easy to convert, no matter the side chain length. In addition, S 2 class species with less-aromatic cores and/or less carbon numbers have better hydrogenation reactivities. Meanwhile, S 2 class species with long and/or complex chains would be easy to cleavage into small ones under the reaction conditions. Compare to S 1 class species, S 2 species are more active. The potential transformation of sulfur compounds in HDT of subfractions of atmospheric residua were inferred from the DBE distribution and carbon number data by involving SFEF, methylation followed by FT-ICR MS for sulfur species of SFEF subfractions and their HDT products. The results may help understanding of the heavy oil sulfur removal sequence and catalyst/ process optimization for heavy oil desulfurization and thereby assist the efficient production of clean transporation fuels.