The Zambezi Delta basin is a passive marginal basin located on the East African coast that has good oil and gas exploration potential. Due to the special geological evolutionary background of the Beira High in the Zambezi Delta basin, it has a low gravity anomaly, and the existing seismic survey lines do not cover the whole basin; therefore, it is difficult to interpret the structural characteristics of the whole basin based solely on gravity or seismic data. Based on satellite altimetry gravity anomaly data, this study infers the distribution characteristics of faults in the Zambezi Delta basin by using the normalized vertical derivative of the total horizontal derivative (NVDR-THDR) technique. Then, constrained by seismic data, the gravity anomaly at the Moho interface is extracted by using the fast forward method of the double-interface model of the gravity anomaly, and this anomaly is then removed from the Bouguer gravity anomaly to obtain the sedimentary layer gravity anomaly. The thickness of the sedimentary strata is obtained by inversing the sedimentary basement depth of the whole basin. Then, uplifts and depressions are divided based on a sedimentary layer thickness of 3 km. This research demonstrates that the Zambezi Delta basin mainly features nearly SN-trending and NE-trending faults and that these faults exhibit east‒west partitioning. The nearly SN-trending strike-slip faults controlled the sedimentary development of the basin, and the NE-trending tensile faults may have acted as migration channels for oil, gas and magma. The “overcompensation” effect of the Moho interface gravity anomaly on the gravity anomaly of the sedimentary layer is caused by the depression of the Moho interface beneath the Beira High, which results in a low gravity anomaly value for the Beira High. The pattern of uplifts and depressions trends NE and has the structural characteristics of east‒west blocks.

The Kyushu–Palau Ridge (KPR), an anti-S-shaped submarine highland at the center of the Philippine Sea Plate (PSP), is considered the residual arc of the Izu–Bonin–Mariana Island Arc, which retains key information about the cessation of the Western Philippine Basin (WPB) expansion and the Parece Vela Basin (PVB) breakup. Herein, using the new generation of satellite altimetry gravity data, high-precision seafloor topography data, and newly acquired ship-borne gravity data, the topographic and gravity characteristics of the KPR mid-southern section and adjacent region are depicted. The distribution characteristics of the faults were delineated using the normalized vertical derivative–total horizontal derivative method(NVDR-THDR) and the minimum curvature potential field separation method. The Moho depth and crustal thickness were inverted using the rapid inversion method for a double-interface model with depth constraints. Based on these results, the crust structure features in the KPR mid-southern section, and the “triangular” structure geological significance where the KPR and Central Basin Rift (CBR) of the WPB intersect are interpreted. The KPR crustal thickness is approximately 6–16 km, with a distinct discontinuity that is slightly thicker than the normal oceanic crust. The KPR mid-southern section crust structure was divided into four segments (S1–S4) from north to south, formed by the CBR eastward extension joint action and clockwise rotation of the PVB expansion axis and the Mindanao fault zone blocking effect.

Coal-type source rocks include both coal and terrigenous marine source rocks. By studying the distribution of secondary depressions, uplifts, as well as the characteristics of peat formation and accumulation in the northern marginal sea basin of the South China Sea, and combining them with coal formation characteristics observed in other basins, five genetic theories on the relationship between peat accumulation and dispersed organic matter accumulation are proposed. The northern marginal sea basin of the South China Sea is characterized by “disadvantageous coals formation and favorable terrigenous marine source rocks formation.” This paper provides a distribution map of coal seams and terrigenous marine source rocks in the Qiongdongnan Basin and determines their distribution patterns. Research shows that the migration of sedimentary facies in the basins and inner depressions led to the formation and migration of the peat accumulation centers. In addition, the vertical migration of the peat accumulation centers led to planar migration, which is actually a type of coupling relationship.Previous research results have revealed that the formation of coal-type source rock is multi-phased. The marginal sea basin is composed of several fault-depression basins, with each basin developing a second order of depression and uplift. There is no unified basin center or depositional center to be found. As a result, the concentration centers of coal-forming materials also vary greatly. Based on the distribution characteristics of coal-type source rocks in different basins within the marginal sea basins of the South China Sea, the research results have practical significance and provide guidance for exploring coal-type oil and gas reservoirs in this area.

Deepwater oil and gas exploration is the key to sustainable breakthroughs in petroleum exploration worldwide. The Central Canyon gas field has confirmed the Lingshui Sag is a hydrocarbon-generating sag, and the deepwater reservoirs in the Lingshui Sag still have more fabulous oil and gas exploration potential. Based on drilling data and three-dimensional (3D) seismic data, this paper uses seismic facies analysis, seismic attribute analysis, and coherence slice analysis to identify the types of submarine fans (lobe-shaped and band-shaped submarine fans) that developed in the Lingshui Sag during the Middle Miocene, clarify the source-to-sink system of the submarine fans and discuss the genesis mechanism of the submarine fans. The results show that: (1) the deepwater source-to-sink system of the Lingshui Sag in the Middle Miocene mainly consisted of a “delta (sediment supply) - submarine canyon (sediment transport channel) - submarine fan (deepwater sediment sink)” association; (2) the main factor controlling the formation of the submarine fans developed in the Lingshui Sag was on the relative sea level decline; and (3) the bottom current reworked the lobe-shaped submarine fan that developed in the northern Lingshui Sag and formed the band-shaped submarine fan with a greater sand thickness. This paper aims to provide practical geological knowledge for subsequent petroleum exploration and development in the deepwater area of the Qiongdongnan Basin through a detailed analysis of the Middle Miocene submarine fan sedimentary system developed in the Lingshui Sag.

Multiple borehole samples are collected from the Baiyun Depression in deep-water area of the northern South China Sea (SCS) in an effort to reconstruct transgression processes during the Paleogene based on palynalgal analysis. This study indicates that the Baiyun Depression generated a large group of palynopore assemblages and fluvial/lacustrine-related algae during the early and middle Eocene when the Wenchang Formation was deposited. The entire depression was dominated by fluvial and lacustrine facies before transgression. Its eastern and southeastern sags transitioned to shallow marine environment by generating a large abundance of marine dinoflagellates during the Enping deposition of the late Eocene. Meanwhile, the southern uplift zone simply yielded fluvial/lacustrine-related palynopores and algae, and was dominated by the fluvial and lacustrine environment during the early stage of the Enping Formation, prior to shifting into transitional setting in the later period. Northwestern sags remained extensive fluvial and delta facies without existence of marine dinoflagellates. It was until the depositional stage of the Zhuhai Formation (Oligocene) that the overall depression was strongly impacted from transgression process. Both eastern and southeastern sags were mainly under deep marine setting on a continental slope while northwestern and southern areas developed transitional facies. Although distribution and accumulation patterns varied greatly among sub-sags, the overall Baiyun Depression was characterized by widespread development of marine dinoflagellates. It should be noted that the northwestern sag also partly generated large-scale river delta deposits. Due to the eustatic rise and change of SCS spreading axis, the overall Baiyun Depression was mostly influenced by the deep marine environment on a continental slope during the early Miocene. Both northwestern sag and southern uplift zone were found plentiful marine dinoflagellates. In summary, transgression initiated from the eastern and southeastern Baiyun Depression before subsequently progressing into the farther west. Evolution of transgression process is also greatly consistent with the gradual westward expansion of the SCS.

Significant advancements have been made in the study of Mesozoic granite buried hills in the Songnan Low Uplift (SNLU) of the Qiongdongnan Basin. These findings indicate that the bedrock buried hills in this basin hold great potential for exploration. Borehole samples taken from the granite buried hills in the SNLU were analyzed using apatite fission track (AFT) and zircon (U-Th)/He data to unravel the thermal history of the basement rock. This information is crucial for understanding the processes of exhumation and alteration that occurred after its formation. Thermal modeling of a sample from the western bulge of the SNLU revealed a prolonged cooling event from the late Mesozoic to the Oligocene period (~80−23.8 Ma), followed by a heating stage from the Miocene epoch until the present (~23.8 Ma to present). In contrast, the sample from the eastern bulge experienced a more complex thermal history. It underwent two cooling stages during the late Mesozoic to late Eocene period (~80−36.4 Ma) and the late Oligocene period (~30−23.8 Ma), interspersed with two heating phases during the late Eocene to early Oligocene period (~36.4−30 Ma) and the Miocene epoch to recent times (~23.8−0 Ma), respectively. The differences in exhumation histories between the western and eastern bulges during the late Eocene to Oligocene period in the SNLU can likely be attributed to differences in fault activity. Unlike typical passive continental margin basins, the SNLU has experienced accelerated subsidence after the rifting phase, which began around 5.2 Ma ago. The possible mechanism for this abnormal post-rifting subsidence may be the decay or movement of the deep thermal source and the rapid cooling of the asthenosphere. Long-term and multi-episodic cooling and exhumation processes play a key role in the alteration of bedrock and contribute to the formation of reservoirs. On the other hand, rapid post-rifting subsidence (sedimentation) promotes the formation of cap rocks.

The distribution of oil and gas resources is intricately connected to the underlying structure of the lithosphere. Therefore, investigating the characteristics of lithospheric thickness and its correlation with oil and gas basins is highly important. This research utilizes recently enhanced geological–geophysical data, including topographic, geoid, rock layer thickness, variable rock layer density, and interface depth data. Employing the principles of lithospheric isostasy and heat conduction, we compute the laterally varying lithospheric thickness in the China seas and adjacent areas. From these results, two pivotal parameters for different types of oil and gas basins were statistically analyzed: the minimum lithospheric thickness and the relative fluctuation in lithospheric thickness. A semiquantitative analysis was used to explore the connection between these parameters and the hydrocarbon abundance within the oil and gas basins. This study unveils distinct variations in lithospheric thickness among basins, with oil and gas rich basins exhibiting a thicker lithosphere in the superimposed basins of central China and a thinner lithosphere in the rift basins of eastern China. Notably, the relative fluctuations in lithospheric thickness in basins demonstrate significant disparities: basins rich in oil and gas often exhibit greater thickness fluctuations. Additionally, in the offshore basins of China, a conspicuous negative linear correlation is observed between the minimum lithospheric thickness and the relative fluctuation in lithospheric thickness. This study posits that deep-seated thermal upwelling results in lithospheric undulations and extensional thinning in oil and gas basins. Concurrently, sustained deep-seated heat influences sedimentary materials in basins, creating favorable conditions for oil and gas generation. The insights derived from this study contribute to a quantitative understanding of the intricate relationships between deep lithospheric structures and oil and gas basins. These findings provide valuable guidance for future oil and gas exploration in the studied areas.

The development of the Paleogene coal seams in China’s offshore basin areas generally had the characteristics of coal measures with large thicknesses, large numbers of coal seams, thin single coal seams, poor stability, scattered vertical distribution, and a wide distribution range. This study selected the Enping Formation of the Zhu Ⅰ Depression in the northern section of the South China Sea as an example to determine the macro-control factors of the development of the Paleogene coal seam groups. An analysis was carried out on the influencing effects and patterns of the astronomical cycles related to the development of the thin coal seam groups in the region. A floating astronomical time scale of the Enping Formation was established, and the sedimentary time limit of the Enping Formation was determined to be approximately 6.15 Ma±. In addition, the cyclostratigraphy analysis results of the natural gamma-ray data of Well XJ in the Enping Formation of the Xijiang Sag revealed that the development of the thin coal seams had probably been affected by short eccentricity and precession factors. The formation process of coal seams was determined to have been affected by high seasonal contrast, precipitation, and insolation. During the periods with high values of short eccentricity, the seasonal contrasts tended to be high. During those periods, fluctuations in the precession controls resulted in periodic volume changes in precipitation and insolation of the region, resulting in the development of thin coal seams. It was also found that the periods with low precession were the most conducive to coal seam development. On that basis, combined with such factors as sedimentary environmental conditions conducive to the development of thin coal seam groups, this study established a theoretical model of the comprehensive influences of short eccentricity and precession on the development and distribution of Paleogene thin coal seam groups in offshore lacustrine basins. The patterns of the Paleogene astronomical periods and paleoclimate evolution, along with the control factors which impacted the development of thin coal seam groups in offshore lacustrine basins, were revealed.

Mussel aquaculture and large yellow croaker aquaculture areas and their environmental characteristics in Zhoushan were analyzed using satellite data and in-situ surveys. A new two-step remote sensing method was proposed and applied to determine the basic environmental characteristics of the best mussel and large yellow croaker aquaculture areas. This methodology includes the first step of extraction of the location distribution and the second step of the extraction of internal environmental factors. The fishery ranching index (FRI1, FRI2) was established to extract the mussel and the large yellow croaker aquaculture area in Zhoushan, using Gaofen-1 (GF-1) and Gaofen-6 (GF-6) satellite data with a special resolution of 2 m. In the second step, the environmental factors such as sea surface temperature (SST), chlorophyll a (Chl-a) concentration, current and tide, suspended sediment concentration (SSC) in mussel aquaculture area and large yellow croaker aquaculture area were extracted and analyzed in detail. The results show the following three points. (1) For the extraction of the mussel aquaculture area, FRI1 and FRI2 are complementary, and the combination of FRI1 and FRI2 is suitable to extract the mussel aquaculture area. As for the large yellow croaker aquaculture area extraction, FRI2 is suitable. (2) Mussel aquaculture and the large yellow croaker aquaculture area in Zhoushan are mainly located on the side near the islands that are away from the eastern open waters. The water environment factor template suitable for mussel and large yellow croaker aquaculture was determined. (3) This two-step remote sensing method can be used for the preliminary screening of potential site selection for the mussels and large yellow croaker aquaculture area in the future. the fishery ranching index (FRI1, FRI2) in this paper can be applied to extract the mussel and large yellow croaker aquaculture areas in coastal waters around the world.

The importance of the Atlantic Multidecadal Oscillation (AMO) and Interdecadal Pacific Oscillation (IPO) in influencing zonally asymmetric changes in Antarctic surface air temperature (SAT) has been established. However, previous studies have primarily concentrated on examining the combined impact of the contrasting phases of the AMO and IPO, which have been dominant since the advent of satellite observations in 1979. This study utilizes long-term reanalysis data to investigate the impact of four combinations of +AMO+IPO, –AMO–IPO, +AMO–IPO, and –AMO+IPO on Antarctic SAT over the past 115 years. The +AMO phase is characterized by a spatial mean temperature amplitude of up to 0.5℃ over the North Atlantic Ocean, accompanied by positive sea surface temperature (SST) anomalies in the tropical eastern Pacific and negative SST anomalies in the extratropical-mid-latitude western Pacific, which are indicative of the +IPO phase. The Antarctic SAT exhibits contrasting spatial patterns during the +AMO+IPO and +AMO–IPO periods. However, during the –AMO+IPO period, apart from the Antarctic Peninsula and the vicinity of the Weddell Sea, the entire Antarctic region experiences a warming trend. The most pronounced signal in the SAT anomalies is observed during the austral autumn, whereas the combination of –AMO and –IPO exhibits the smallest magnitude across all the combinations. The wavetrain excited by the SST anomalies associated with the AMO and IPO induces upper-level and surface atmospheric circulation anomalies, which alter the SAT anomalies. Furthermore, downward longwave radiation anomalies related to anomalous cloud cover play a crucial role. In the future, if the phases of AMO and IPO were to reverse (AMO transitioning to a negative phase and IPO transitioning to a positive phase), Antarctica could potentially face more pronounced warming and accelerated melting compared to the current observations.