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In recent years, abundant natural gas have been found in microbial carbonates in the fourth member of the Leikoupo Formation in western Sichuan Basin. In this study, from the observation of 626 microbial thin sections, four types of microbial carbonates are classified based on the differences of meso-structures. Among them, thrombolites and stromatolites are subdivided into eight types based on the differences of micro-structures. Six types of microbial micro-structure association (MSA) are identified, and are mainly developed in microbial mounds. The energy of sedimentary environment and hydrodynamic conditions of them from low to high is MSA-5, MSA-1, MSA-6, MSA-3, MSA-4 and MSA-2. Because of the arid climate in the Annie Period, a restricted platform are developed in T2l43 in western Sichuan Basin, and the sedimentary faces are lagoon (gypsiferous lagoon or salt lake in evaporate conditions), microbial mounds, shoals, inner platform shoals and open sea from the east to the west. Microbial micro-structure not only affects the pore evolution of microbial carbonate reservoirs, but also affects the diagenesis of microbial carbonate reservoirs of the Lei-4.

This article examines China’s approach to integrating Korea into Chinese territory in history and its significant influence on the construction of the Chinese Empire and state. It discusses major instances of Chinese integration of Korea before and under the Mongol Empire and reveals that the tributary relationship with Korea that the Ming and Qing dynasties cultivated in the post-Mongol period allowed Korea to maintain a significant degree of independence from China. It points out that the Qing imperial discourse described Korea as a province by combining the Manchu ruling house’s and European Jesuits’ understandings of the Chinese empire. Qing China refrained from colonizing Korea in the nineteenth century primarily because of the post-Mongol shift in its policy toward the country and because of its Confucian ethos. The article further argues that China did not become a modern state until the 1950s, when the Chinese option of provincializing Korea permanently disappeared.

Since the 1990s, the Chinese-North Korean border region has undergone a gradual transformation into a site of intensified cooperation, competition, and intrigue. These changes have prompted a significant volume of critical scholarship and media commentary across multiple languages and disciplines. Drawing on existing studies and new data, Decoding the Sino-North Korean Borderlands brings much of this literature into concert by pulling together a wide range of insight on the region's economics, security, social cohesion, and information flows. Drawing from multilingual sources and transnational scholarship, this volume is enhanced by the extensive fieldwork undertaken by the editors and contributors in their quests to decode the borderland. In doing so, the volume emphasizes the link between theory, methodology, and practice in the field of Area Studies and social science more broadly.

In recent years, the discovery of two gas fields in the fourth member of the Leikoupo Formation in the Western Sichuan Basin of SW China confirmed the exploration potential of microbial carbonates. The aim of the present study is to clarify the formation mechanism of the microbial reservoirs in the Leikoupo Formation. For this purpose, lithofacies, depositional environments, and diagenesis analyses were performed in samples collected from cores of 12 wells. The climate of study area was arid during Anisian time, and the water body was restricted. In such a climate, an evaporitic environment was developed, where ten types of lithofacies, dominated by microbial carbonates and gypsum rocks, were recognized. Thrombolites and stromatolites are the main high-quality reservoirs rock types in the fourth member of the Leikoupo Formation in the Western Sichuan Basin of SW China, which developed as microbial mounds, with reservoir space of microbial inter-clot pores, intra-clot pores, fenestral pores, inter-crystalline pores, and cracks. The microbial inter-clot pores are the main reservoir space, formed by trapping and binding of marls by benthic microbial communities. These pores were partially filled with evaporites because of the arid climate, which were subsequently dissolved (mainly gypsum) in the syn-depositional period, thus greatly improving the quality of reservoirs. Although some pores were occluded by multi-stage cements during the burial stage, major pores were well preserved own to the early dolomitization, rapid burial of the Leikoupo Formation, and early charging of hydrocarbon. The early dolomitization enhanced the anti-compaction ability of microbial carbonates during the burial stage. Rapid burial of the Leikoupo succession slowed down early cementation, and it also accelerated the maturation and expulsion process source rock to promote early charging of hydrocarbon in pores, which created a closed system, inhibiting strong burial cementation.

Deep and thick Cambrian dolostone reservoirs are important and potential petroleum exploration targets in the Tarim Basin. To improve understanding of the origin of deeply buried microbial-dominated carbonate reservoir of the Lower Cambrian Xiaoerbulake Formation in Bachu-Tazhong area, the influences of microfacies types and carbonate diagenesis on porosity development were carefully investigated using petrographic observations and geochemical analyses from outcrop and core samples. Fifteen microfacies types (MF1-15) were identified in (1) tidal flat, (2) lagoon, (3) ramp-crest shoal, (4) sheltered proximal middle-ramp, (5) microbial mounds-biostromes proximal middle-ramp, and (6) distal middle-ramp environments on a gentle dipping carbonate ramp. A third-order depositional sequence consists of transgressive and highstand systems tract corresponding to the lower and upper member of the Xiaoerbulake Formation respectively. The HST section was characterized by extensively high-energy ramp-crest shoals and microbial mounds-biostromes proximal middle-ramp with moderate–good reservoir quality, while the TST section was composed of distal middle ramp and scattered microbial mounds with poor-non reservoir quality. The vertical cyclic pattern of porosity of microbial-related and dolo-grainstone microfacies types resulted from frequent exposure to meteoric leaching due to high-frequency relative sea level changes, as demonstrated by the diagenetic sequence. Main pore types are intergranular, vuggy pores, and microbial-related framework pores. Dolomitization occurred relatively early in shallow diagenetic environments, which may have improved the resistivity of carbonate rocks against chemical compaction. Preservation of porosity was likely attributed to a high-pressure closed diagenetic system under the middle Cambrian evaporites. The subsequent faulting and uplifting may have locally destroyed the reservoirs and increased the reservoir heterogeneity. This work would provide new sights for better understanding of the microbial-dominated carbonate reservoirs in deeply buried Lower Cambrian strata worldwide.

Yuanchong Wang (University of Delaware) reviews a book by Sun Weiguo, Cong “zun Ming” dao “feng Qing”: Chaoxianwangchao dui Qing yishi de shanbian, 1627–1910 從 “尊明” 到 “奉清”: 朝鮮王朝對清意識的嬗變, 1627–1910 [From “honoring the Ming” to “submitting to the Qing”: The transformation of Chosŏn Korea’s attitude toward Qing China, 1627–1910]. Wang concludes that, although Sun’s latest book “will surely stay on the list of must-read books in the East Asian academia for many years to come,” it also “leaves much room for future groundbreaking contributions to the literature.” In this way, Wang invites younger scholars to challenge the conventional historiographical approach centered on textual research.

The Qixia Formation and Maokou Formation of Middle Permian in the southwestern Sichuan Basin were pervasively dolomitized during the diagenetic history. Petrographically, four types of dolomites, namely three replacive dolomites (Rd1, Rd2, and Rd3) and one dolomite cement (Cd), were distinguished. Rd1 dolomite occurs as very fine (&lt, 50 µm), planar-s to nonplanar crystals, Rd2 dolomite shows planar-e to planar-s crystal shapes with fine crystal sizes (50–250 µm) and is characterized by center-frog and margin-clear, Rd3 dolomite occurs as medium to coarse (250 µm–2 mm), nonplanar crystals, and Cd dolomite is characterized by saddle crystals filling dissolution pores and/or fractures, translucent white color in the hand samples, and strong sweeping extinction under cross-polarized light. In areas close to reactivated basement faults (Zhangcun outcrop and well Hanshen1), Rd3 (~65% by abundance) was the dominant type of replacement dolomite and minor amounts of Rd1 and Rd2 (~10%) were found in this area. Cd (~25%) was extensively developed in fractures and dissolution pores, whereas, in areas far away from the fault zones (Xinjigu outcrop), Rd1 (~20%) and Rd2 (~55%) were dominant replacement dolomites, and only a small portion of them were recrystallized to form Rd3 (~20%), with minor Cd (~5%) dolomite occurring in some dissolution pores. The δ13CV-PDB (−0.37‰ to 4.32‰) and δ18OV-PDB values (−7.41‰ to −5.19‰), 87Sr/86Sr ratios (0.707085 to 0.707795), and rare earth elements (REE) patterns (flat REE patterns with slight light rare earth element (LREE) enrichment and slight negative Ce anomalies) suggest that Rd1 dolomite was formed penecontemporaneously in an evaporitic tidal flat evaporation environment with salinities higher than seawater. The Rd2 dolomite, characterized by δ13CV-PDB (−0.18‰ to 4.89‰) and δ18OV-PDB values from −6.6‰ to −5.5‰, 87Sr/86Sr ratios from 0.707292 to 0.707951, and LREE enrichment and slight negative Ce anomalies, was interpreted as forming from the recrystallization of Rd1 at shallow burial. The δ18OV-PDB values (−12.01‰ to −8.23‰), the prominent positive anomaly of Eu, high 87Sr/86Sr ratios (0.7081–0.7198) and high fluid inclusion homogenization temperatures (149–255 °C) suggest that Rd3 and Cd dolomite were formed from hot fluids. Based on regional stratigraphic data, the Rd3 and Cd were likely formed at depths less than 1500 m, thus, the ambient burial temperature would be lower than 85 °C. The high fluid temperatures recorded by fluid inclusions, thus, indicate that the dolomitization was of hydrothermal nature. The δ18OV-SMOW values, homogenization temperatures, and salinities of the fluid inclusions of Rd3 and Cd in proximal areas were systematically higher than those in distal areas, suggesting that the hydrothermal fluid ascended along faults in proximal areas and then migrated laterally along the strata to distal areas. The dolomites of the Middle Permian carbonates in the southwestern Sichuan Basin, thus, resulted from different dolomitization phases, and the latter hydrothermal dolomitization was controlled by a combination of strata and structures.

By examining transformations of Manchu–Chosŏn relations from 1616 to 1643, the author argues that the Manchu regime invoked its new position of the “Central Kingdom” to construct its politico-cultural identity as “Zhongguo” before 1644. After it imposed a “younger brother” relationship on Chosŏn in 1627, the Manchu regime developed a new political discourse regarding Chosŏn, the Ming, and other political entities. In this way, it started claiming centrality in the Chinese world. It also expressed the goal of transforming into Zhongguo and began barbarianizing other countries as a concurrent process of its Sinicization. By further imposing the Zongfan (a.k.a. tributary) relationship on Chosŏn in 1637, the Qing started to replace the Ming's central position in the Chinese world and eliminate its former identity as barbarian. The intensive Qing–Chosŏn communications between 1637 and 1643 strengthened the Qing's identity as Zhongguo and contributed to the rise of the “Chosŏn Model” for Qing China.