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A study of paleo-ocean redox environments is important for understanding the deposition of black shale and has practical implications for shale gas exploration. Here, we selected a total of 52 shale samples from JY1 Well, the first shale gas well of commercial exploitation in China, to analyze the redox conditions of Upper Ordovician Wufeng ([O.sub.3w]) and the first member in lower Silurian Longmaxi shale ([S.sub.1][l.sup.1]) in the Jiaoshiba area. Abundant pyrite framboids are observed in these units, with average framboid diameters ranging from 3.1 to 4.7 µm and maximum diameter about 10 µm. Analyses of redox-sensitive trace elements suggest the redox environment has evolved from an anoxic condition in the bottom of Member A to a dysoxic condition in the top of Member A, and to a dysoxic--oxic environment in Members B and C. Graptolite and radiolarian are discovered in these shale samples, indicating an oxygenated seafloor, which seems to be contradictory to the results from pyrite framboids and redox-sensitive trace elements. This contradiction is explained as follows: when the shale was deposited, the sedimentation was dominated by euxinic conditions; however, some oxygen may also occasionally migrate to the bottom water due to oxygen-deficient environment, deglaciation, and (or) strong upwelling of nutrient-enriched seawater, while the limited oxygen and anoxic environment is favorable for the preservation and accumulation of organic matter. Combined with the geological characteristics and redox conditions, Member A, especially the shales at the bottom of Member A, is expected to be the most favorable shale gas reservoir in the Jiaoshiba area. L'etude des conditions d'oxydoreduction des paleooceans est importante pour la comprehension du depot des schistes noirs et a des consequences pratiques pour l'exploration du gaz de schiste. Nous avons choisi un total de 52 echantillons de schiste du puits JY1, le premier puits de gaz de schiste ayant fait l'objet d'une exploitation commerciale en Chine, pour analyser les conditions d'oxydoreduction de la Formation de Wufeng ([O.sub.3]w) de l'Ordovicien superieur et du premier membre du schiste de Longmaxi ([S.sub.1][l.sup.1]) du Silurien inferieur dans la region de Jiaoshiba. Des framboides de pyrite sont observes en abondance dans ces unites, leur diametre moyen allant de 3,1 a 4,7 µm et leur diametre maximum atteignant environ 10 µm. Les analyses d'elements traces sensibles aux conditions d'oxydoreduction donnent a penser que ces conditions sont passees d'anoxiques a la base du Membre A a dysoxiques au sommet de ce membre, puis a un milieu dysoxique--oxique dans les Membres B et C. Des graptolites et radiolaires sont presents dans ces echantillons de schiste, indiquant un fond marin oxygene, ce qui semble contredire les resultats de l'analyse des framboides de pyrite et des elements traces sensibles a l'oxydoreduction. Cette contradiction s'explique comme suit: la sedimentation etait dominee par des conditions euxiniques au moment du depot du schiste; cela dit, de l'oxygene peut a l'occasion migrer vers les eaux du fond marin en raison d'un milieu pauvre en oxygene, de la deglaciation ou d'une forte remontee d'eau de mer enrichie en nutriments, alors qu'un milieu limite en oxygene ou anoxique favorise la preservation et l'accumulation de matiere organique. Au vu des caracteristiques geologiques et des conditions d'oxydoreduction, il est prevu que le Membre A, plus particulierement les schistes a sa base, constitue les reservoirs de gaz de schiste les plus favorables dans la region de Jiaoshiba. [Traduit par la Redaction], Introduction Sichuan Basin, with an area of more than 1.8 x [10.sup.5] [km.sup.2] , is one of the most stable sedimentary basins and significant gas-producing provinces in China (Dai et [...]

This paper aims to study the decoupling status and emission reduction potential of China's petrochemical industry from 1996 to 2019. Firstly, the IPCC method is used to calculate the CO2 emissions of the petrochemical industry in China, then the logarithmic mean Divisia index (LMDI) method is used to identify the influencing factors of CO2 emissions, then the decoupling index is constructed to analyze the dependence of economic development on CO2 emissions, and finally the emission reduction potential model is established by using the influencing factors to reflect the CO2 emission reduction potential of the petrochemical industry. The results reveal that (1) the CO2 emissions can be divided into two stages of slow decline (1996–2000), (2015–2019), and one stage of rapid growth (2000–2015). (2) The energy intensity effect is the most effective factor to restrain CO2 emission, the economic growth effect is the key factor to promote CO2 emission. (3) From 1996 to 2019, there was a weak decoupling relationship between CO2 emission of petrochemical industry and economic development. Strong decoupling only occurred in 1996–2000 and 2015–2019. The CO2 emissions show only three decoupling score: I, II, and III. (4) CO2 mitigation occurred in four sub periods: 1996–2000, 2005–2010, 2010–2015, and 2015–2019. Therefore, the government should establish an energy-saving and environment-friendly industrial production system, intensify the use of clean energy, and optimize the labor force structure. It not only effectively strengthens the decoupling between the petrochemical industry and economic development, but also provides an empirical example for the carbon emission reduction and economic sustainable development of the petrochemical industry in other countries in the world. [ABSTRACT FROM AUTHOR]