No detailed research has been carried out on the oil shales that are interbedded with gravity flow deposits and volcaniclastic rocks in the third Member of the Jiufotang Formation. In order to study ...the impact of basin evolution, gravity flows, and volcanism on oil shale formation, petrology, sedimentology, sequence stratigraphy, organic geochemistry, and elemental geochemistry were used to characterise the oil shales. Extensional tectonic subsidence is suggested as the controlling factor for basin evolution. The predominant maceral in the oil shales is sapropelinite, suggesting organic matter was derived from mainly aquatic organism (especially algae). Element indices (δU, (Cu + Mo)/Zn, Sr/Ba, Th (μg/g), Zr (μg/g), and the chemical index of alteration (CIA) show that the water conditions during deposition of the oil shales were anoxic and brackish, with little terrigenous detrital input and a cold and dry palaeoclimate. Gravity flows were accompanied by the input of terrestrial detritus and a degree of oxygenation of the bottom waters, reducing oil shale formation. Volcanic eruptions ejected intermediate-acidic ashes, not only leading to climate cooling, but also either enhancing algal blooms (by a fertilisation effect due to minor volcanic ash input) or inhibiting algal blooms (by a poisoning effect due to major volcanic ash input). There is synchronicity between the occurrence of rifting, gravity flows, volcanism, and earthquakes. The best periods for oil shale formation were during intermissions between tectonic movement, when there were few gravity flows, volcanic eruptions, or earthquakes. High bioproductivity and lake expansion along with an anoxic environment were the main controlling factors for high-quality oil shale formation. There is a series of oil shale-bearing rift basins formed in northeastern China that share a similar geological setting, so this research provides a useful example for future resource exploration of coeval oil shales in northeastern China.
•Complete third order sedimentary sequence in third member of the Jiufotang Formation.•Tectonic movements triggered synchronous gravity flows, volcanic eruptions, earthquakes.•Evolution of Chaoyang Basin and gravity flows controlled distribution of oil shales.•Volcanic activity influenced algal blooms.•High quality oil shales deposited during intermissions between tectonic movements.
In order to improve the characteristics of uneven melting in the melting process of the horizontal latent heat energy storage system, the triplex-tube latent heat energy storage unit is taken as the ...research object, and the flip mechanism is applied to its melting process. Numerical simulation is used for the research, and the numerical model is verified by experimental data. The results show that under different dimensionless times, the melting performance of the unit can be significantly improved by a single flip. When the dimensionless time is 0.4576, it is found that the total melting time of the unit is reduced by 16.17 %, the average heat absorption rate is increased by 14.7 %, but the total heat energy absorption is reduced by 3.85 %. The results show that the addition of a flip can effectively shorten the melting time and increase the heat absorption rate, but it has a negative effect on the total heat absorption in one melting cycle. Moreover, through the comparison of dynamic flow rate, dynamic temperature response, and temperature interval, it is shown that the addition of flip effectively reduces the negative influence of the hard-to-melt zone on the melting performance of the unit during the melting process. The flip mechanism reduces the proportion of high-temperature phase change material in the melting process and makes the melting process more uniform.
Frequent hyperthermal events during the Eocene (55-47 Ma), primarily characterised by carbon isotope excursions (CIEs), have been identified from marine records worldwide. However, only a few ...excursions have been recognised and described in continental deposits, thereby limiting the understanding of the effect of global warming on terrestrial systems. Thick, dark, organic-rich mudstone containing complete astronomical age information was deposited during the Palaeogene in the Fushun Basin. Based on U–Pb zircon dating and Milankovitch cycle analysis, the astronomical time scale (ATS) of the Fushun Basin was established. Based on the high-resolution chronostratigraphic framework, combined with the negative migration characteristics of organic carbon isotopes (δ13CTOC), three hyperthermal events were identified: Eocene Thermal Maximum 2 (ETM2), Eocene Thermal Maximum (ETM3) and long-term Early Eocene Climatic Optimum (EECO). In particular, several periods of short-term hyperthermal events were identified in the EECO period: L, M, N, O, P, Q, R, S, T, U, V, W, C22nH3, C22nH4, C22nH5, C21rH1, C21rH2, C21rH3, C21rH4, C21rH5, C21nH1 and C21nH2. The records of sea and land hyperthermal events show that the records corresponding to land basins are timelier and more sensitive.
•Established astronomical chronology scale of Eocene in Fushun basin.•The boundary ages of Guchengzi Formation and Lizigou Formation of Eocene in Fushun Basin are determined to be 54.51 Ma.•ETM2, ETM3 and EECO hyperthermal events were found in Eocene strata of Fushun Basin.
The Fushun Basin is a typical continental basin filled with organic-rich fine-grained sedimentary rocks, such as coal, oil shale and greyish green mudstone. Currently, research on this basin ...predominantly focuses on the enrichment mechanisms of organic matter in coal and oil shale and the controlling factors of coal seam transformation to oil shale. However, during the transformation stage, the deposition of oil shale ceased and was converted to interbeds of grey green mudstone and thin oil shale layers. The control mechanism of this type of sedimentary succession is still not clear. In this study, the thick oil shale in the upper part of the Jijuntun Formation (Unit I) and the high-frequency interbedded mudstone and thin oil shale in the Xiloutian Formation (Units II and III) were analysed as key strata. Organic and inorganic geochemical data were analysed to reconstruct the transformation of the various types and sources of organic matter and controlling factors including the palaeoclimate, palaeoweathering, bioproductivity, terrigenous clastic input, palaeosalinity, and redox conditions. Among these, Unit I was affected by humid climate conditions predominantly. The water depth and volume were large, and the input of terrigenous debris was low. Freshwater algae blooms and anoxic conditions led to a supply of organic matter and that was well preserved. This further resulted in a high abundance of organic matter in the sedimentary rocks. Unit II was affected by semihumid-semiarid and arid climate conditions. The lake became shallower while terrigenous clastic input and lake palaeosalinity increased; these changes represented the transition stage from freshwater to brackish water. The lake still exhibited suboxic/anoxic conditions, but the biological living space decreased, resulting in a limited organic matter supply and a low abundance of organic matter in the sediment. Unit III was affected by semihumid-semiarid climate conditions, and the palaeosalinity continued to increase. The lake had brackish water, with a high bioproductivity, a decreased water volume and a limited supply of organic matter. However, brackish water stratification occurred in the lake, which created a strongly anoxic environment and good preservation conditions, resulting in a secondary high abundance of organic matter. A comprehensive analysis indicates that the environmental change caused by the palaeoclimate was the main factor driving the oil shale deposition to cease and the onset to deposit grey green mudstone and thin oil shale in the Fushun Basin, Northeast Asia.
•Different from the previous research, thin layer oil shale layers are also developed in the Xiloutian Formation.•The palaeoclimate, palaeosalinity and bioproductivity showed cycle evolution in the Xiloutian Formation.•High organism supply promoted the formation of thick high-quality oil shale in Jijuntun Formation in anoxic environment.•The excellent preservation condition is the key factor for the formation of oil shale in the Xiloutian Formation.
The Mesozoic was punctuated by relatively brief periods of anomalous warmth associated with pulses of volcanism, intensified weathering, expansive marine anoxia, and increased organic carbon burial. ...These are known as oceanic anoxic events (OAEs). Several OAEs have also been linked to potentially synchronous episodes of increased carbon burial in lacustrine settings, attributed to increased weathering-derived nutrient fluxes. Here we present the Early Aptian oil shale sequences of western Liaoning Province, north China, combining sediment petrology, zircon U-Pb geochronology, carbon isotope chemostratigraphy, as well inorganic and organic geochemical palaeoenvironmental proxies to assess possible causal links to OAE1a. New zircon 206Pb/238U ages (121.06 ± 0.63 Ma, 119.72 ± 0.40 Ma, and 119.9 ± 0.65 Ma) for three tuffs and δ13Corg chemostratigraphic correlation show that the western Liaoning Province oil shale interval formed shortly after widespread marine black shale deposition characteristic of OAE1a had ceased. Elevated concentrations of alginite (dinoflagellate-derived organic matter) in oil shale samples which contain micron-thick tuff layers suggest that arc volcanism in north China was the major factor driving increased lacustrine carbon burial, via volcanic ash fertilisation. This is supported by high values of Babio, C27/C29 ααα-20R steranes, C28/C29 ααα-20R steranes, 4-methylsterane index, dinosterane index, and tetramethylsterane index in these layers, which imply that the input of volcanic ash contributed to a flourishing of brackish/saline-water adapted dinoflagellates, leading to the formation of organic-rich tuff laminae. This is a novel mechanism that is distinct to the processes known to have contributed to enhanced marine organic matter burial on a global scale during OAE1a. This research not only contributes to the study of lacustrine source rocks in north China, but also provides insights into the influence of intermediate-acidic volcanic eruptions on organic carbon burial more generally.
•Zircon 206Pb/238U ages and δ13Corg correlation show that the oil shale interval formed after OAE1a.•Elevated concentrations of alginite in oil shale samples containing micron-thick tuff layers.•Arc volcanism in N China drove increased lacustrine carbon burial by volcanic ash fertilisation.•A mechanism of carbon burial after OAE1a: volcanic ash derived nutrients stimulated algal bloom.•Different from carbon burial mechanism for OAE1a (warmer weather, weathering-derived nutrients).
The quantitative estimation of key parameters of paleotemperature and paleoprecipitation is crucial for paleoclimate reconstruction. Geochemical data from modern sediments are highly consistent with ...climate data, and their relationship can provide an important reference for the quantitative reconstruction of the paleoclimate. In this study, detailed inorganic geochemical analysis was carried out using high-precision sampling of the Paleogene (LFD-1 well) Guchengzi, Jijuntun and Xiloutian Formations in the Fushun Basin located in the mid-latitudes of the Northern Hemisphere. The Eocene Guchengzi Formation (54.51–47.8 Ma) and Jijuntun Formation (47.8–41.2 Ma) in the Fushun Basin were found to have been deposited under a humid climate. The lower (41.2–40.1 Ma) and upper (40.1–37.8 Ma) parts of the Xiloutian Formation were characterized by semiarid and semihumid–semiarid climates, respectively, which is very similar to the paleoclimatic information reflected by organic carbon isotopes. The Eocene Thermal Maximum 2 (ETM2, ~ 53.7 Ma), Early Eocene Climatic Optimum (EECO, ~ 53.1–46.5 Ma, Eocene Thermal Maximum 3 (ETM 3, ~ 52.8 Ma), and Middle Eocene Climatic Optimum (MECO, ~ 40.7–40.1 Ma) events significantly enhanced chemical weathering during these periods. The rapid increase in
p
CO
2
concentration leads to an increase in temperature, precipitation, and surface runoff, exhibiting strong chemical weathering. The mean annual temperature (MAT
a
) and mean annual precipitation (MAP
a
, MAP
b,
and MAP
c
) were estimated using parameters, such as the corrosion index without potassium (CIA-K), CaO/Al
2
O
3
, and (Na
2
O + K
2
O)/Al
2
O
3
. Comparing MAP
a
, MAP
b
, and MAP
c
with the MAP estimated using pollen data, MAP
a
and MAP
b
were found to be more sensitive to the climate during high precipitation periods (precipitation > 1000 mm, Guchengzi Formation), and the recovered average precipitation was similar to MAP. In contrast, MAP
c
was more sensitive to the climate during low precipitation periods (precipitation < 1000 mm, Jijuntun, and Xiloutian Formations), with higher accuracy. To fully consider the influence of soluble inorganic salts Ca
2+
and Na
+
, multivariate linear equations of CIA-K and CaO/Al
2
O
3
with CIA, and CIA-K and CaO/Al
2
O
3
with MAP were constructed, namely MAP
d
and MAP
e
. The results show that MAP
e
has the highest performance and can be effectively used to estimate the change of paleoprecipitation in Northeast Asia.
The response of terrestrial ecosystems to Eocene hyperthermal events remains poorly understood. In this paper, we report palynological assemblages from an astronomically-calibrated Eocene succession ...in the Fushun Basin of northeast China, in which previous δ13C studies have identified the Eocene Thermal Maxima 2 and 3 (ETM2, ETM3), the Early Eocene Climatic Optimum (EECO), and the Middle Eocene Climatic Optimum (MECO). In the samples that are directly associated with hyperthermal events, palynoassemblages show significant increases in the abundance of conifer pollen, especially Abietineaepollenites and Taxodiaceaepollenites, and fern spores of Polypodiaceaesporites, while angiosperm taxa reduce in frequency. Quantitative palaeoclimate parameters derived through the application of the Coexistence Approach to palynological assemblages indicate marked changes in temperature and humidity during hyperthermal events. These changes were most significant during ETM2 when mean annual temperature increased by 3–5 °C and mean annual precipitation increased by approximately 600 mm above background levels, but similar perturbations are also associated with the other hyperthermal events. An increase in organic abundance in lacustrine oil shale facies during hyperthermal events may imply that elevated humidity drove enhanced runoff, nutrient supply, and eutrophication of the hydrologically-open lake basins at a time when terrestrial carbon export from humid forests was also enhanced. Findings demonstrate that short-term bursts of Eocene warming drove major turnovers in the mid-latitude vegetation of Asia, reworking landscapes, and transforming regional hydrology.
•We describe palynoassemblages from an astronomically-calibrated Eocene succession in northeastern China.•Palaeoclimate analysis of assemblages indicates that MAT and MAP increased during hyperthermal events.•Eocene Thermal Maximum 2 showed the largest rise of MAP (3–5 °C) and MAP (600 mm)•Short-term bursts of Eocene warming drove major turnovers in the mid-latitude vegetation of Asia, reworking landscapes and hydrology
Abstract Exotic quantum states arise from the interplay of various degrees of freedom such as charge, spin, orbital, and lattice. Recently, a short-ranged charge order (CO) was discovered deep inside ...the antiferromagnetic phase of Kagome magnet FeGe, exhibiting close relationships with magnetism. Despite extensive investigations, the CO mechanism remains controversial, mainly because the short-ranged behavior hinders precise identification of CO superstructure. Here, combining multiple experimental techniques, we report the observation of a long-ranged CO in high-quality FeGe samples, which is accompanied with a first-order structural transition. With these high-quality samples, the distorted 2 × 2 × 2 CO superstructure is characterized by a strong dimerization along the c -axis of 1/4 of Ge1-sites in Fe 3 Ge layers, and in response to that, the 2 × 2 in-plane charge modulations are induced. Moreover, we show that the previously reported short-ranged CO might be related to large occupational disorders at Ge1-site, which upsets the equilibrium of the CO state and the ideal 1 × 1 × 1 structure with very close energies, inducing nanoscale coexistence of these two phases. Our study provides important clues for further understanding the CO properties in FeGe and helps to identify the CO mechanism.
To save and better deploy waste heat, the use of a mobilized heat storage system (MHSS) with phase change enhancement means is developed. In this paper, three kinds of gradient structures (positive ...gradient, negative gradient, and non-gradient) are designed in the MHSS system. The uniform porosity is 94% in the non-gradient structure, and the gradient porosities are 86%, 93%, and 98% in the gradient structure, respectively. Numerical models are developed to explore the contribution of the graded metal foam structure to the heat storage and release process. An economic analysis and comparison of MHSS systems with different heat transfer models are carried out. The results show that the positive gradient case can promote the thermal cycle of the melting and solidification process, while the negative gradient case inhibits the thermal cycle. The positive gradient case can reduce the melting time by 9.7% and the solidification time by 4.4%, while the negative gradient can prolong the melting time by 31.4% and the solidification time by 35.9%. Although graded metal foam increases the initial investment by 76.09%, the 1 KW·h heat cost of graded metal foam is reduced by 10.63% compared to pure phase change material (PCM). It is cost-effective in the long run of thermal cycles.
Intertwined spin and charge orders have been widely studied in high-temperature superconductors, since their fluctuations may facilitate electron pairing; however, they are rarely identified in ...heavily electron-doped iron selenides. Here, using scanning tunneling microscopy, we show that when the superconductivity of (Li
Fe
OH)Fe
Se is suppressed by introducing Fe-site defects, a short-ranged checkerboard charge order emerges, propagating along the Fe-Fe directions with an approximately 2a
period. It persists throughout the whole phase space tuned by Fe-site defect density, from a defect-pinned local pattern in optimally doped samples to an extended order in samples with lower T
or non-superconducting. Intriguingly, our simulations indicate that the charge order is likely driven by multiple-Q spin density waves originating from the spin fluctuations observed by inelastic neutron scattering. Our study proves the presence of a competing order in heavily electron-doped iron selenides, and demonstrates the potential of charge order as a tool to detect spin fluctuations.
