Terrestrial records of the early Albian Ocean Anoxic Event:Evidence from the Fuxin lacustrine basin,NE China

The early Albian Oceanic Anoxic Event 1 b(OAE 1 b) is well documented in the Tethys, Pacific and North Atlantic, but few studies have evaluated whether or not terrestrial records of OAE 1 b exist. In order to identify terrestrial records of the early Albian OAE 1 b and to infer possible driving mechanisms, an integrated multi-proxy study from the late Aptian to Albian in the Fuxin lacustrine basin was conducted,including thick, organic-rich black mudstones, total organic carbon(TOC), organic carbon isotopes(d13 Corg), mercury concentration(Hg) and results from pyrolysis analyses(S2, Tmaxand HI). Results show three distinct short-term negative d13 Corgexcursions corresponding with relatively high TOC values,which could be counterparts of the Kilian, Paquier and Leenhardt sub-events of the early Albian OAE1 b. Atmospheric CO2 concentration(p CO2) recovered from C3 plant d13 Corgcompositions indicates an increasing trend in Unit C during the early Albian, and there are three short-term increases of p CO2 corresponding to the three sub-events of OAE 1 b at this time interval. We infer that a trend of increasing p CO2 during the Kilian sub-event in the study area is closely related to volcanism. Continental weathering calculated using chemical weathering indices(CIA, WIP and MIA(O)) show an increasing trend during the OAE 1 b interval, likely resulting from warmer and more humid conditions. Mixed sources of terrestrial plants and lacustrine plankton demonstrated by pyrolysis analyses(HI vs. Tmaxand S2 vs. TOC), indicate a terrestrial contribution to the organic-rich sediments of the Kilian, Paquier and Leenhardt sub-events of OAE 1 b. We suggest that a CO2-forced greenhouse effect during the early Albian might have triggered the relatively warm and humid palaeoclimatic conditions, and intensified chemical weathering that combined to create high nutrient and organic matter levels that were flushed into lakes contributing to eutrophication and anoxia in lacustrine and in contemporaneous oceanic systems.

In memory of respected Prof.Zeng-Zhao Feng

January 13,2023 Professor Feng left us in such a hurry,and his voice and smile will always remain in our hearts.Since I participated in Prof.Feng's carbonate petrology course in 1983,my communication with Prof.Feng has not stopped,and I regard myself as Professor Feng's postgraduate student outside the program.I often participated in the seminars convened by Prof.Feng,participated in the discussion of relevant issues,listened to his teachings,and benefited a lot.

Lithofacies palaeogeography of the Carboniferous and Permian in the Qinshui Basin, Shanxi Province, China

The Qinshui Basin in the southeastern Shanxi Province is an important area for coalbed methane(CBM) exploration and production in China, and recent exploration has revealed the presence of other unconventional types of gas such as shale gas and tight sandstone gas. The reservoirs for these unconventional types of gas in this basin are mainly the coals, mudstones, and sandstones of the Carboniferous and Permian; the reservoir thicknesses are controlled by the depositional environments and palaeogeography. This paper presents the results of sedimentological investigations based on data from outcrop and borehole sections, and basin-wide palaeogeographical maps of each formation were reconstructed on the basis of the contours of a variety of lithological parameters. The palaeogeographic units include the depositional environments of the fluvial channel, flood basin(lake), upper delta plain, lower delta plain, delta front, lagoon, tidal flat, barrier bar, and carbonate platform.The Benxi and Taiyuan Formations are composed mainly of limestones, bauxitic mudstones,siltstones, silty mudstones, sandstones, and economically exploitable coal seams, which were formed in delta, tidal flat, lagoon, and carbonate platform environments. The Shanxi Formation consists of sandstones, siltstones, mudstones, and coals; during the deposition of the formation, the northern part of the Qinshui Basin was occupied mainly by an upper delta plain environment, while the central and southern parts were mainly occupied by a lower delta plain environment and the southeastern part by a delta front environment. Thick coal zones occur in the central and southern parts, where the main depositional environment was a lower delta plain. The thick coal zones of the Taiyuan Formation evidently occur in the sandstone-rich belts, located mainly in the lower delta plain environment in the northern part of the basin and the barrier bar environments in the southeastern part of the basin. In contrast, the thick coal zones of the Shanxi Formation extend over the mudstone-rich belts, located in the areas of the lower delta plain environments of the central and southern parts of the Basin.The Xiashihezi, Shangshihezi, and Shiqianfeng Formations consist mainly of red mudstones with thick-interbedded sandstones. During the deposition of these formations, most areas of the basin were occupied by a fluvial channel, resulting in palaeogeographic units that include fluvial channel zones and flood basins. The fluvial channel deposits consist mainly of relatively-thick sandstones, which could have potential for exploration of tight sandstone gas.

Characteristics of Early Cretaceous wildfires in peat-forming environment, NE China

Inertinite maceral compositions in coals from the Early Cretaceous Erlian, Hailar, and Sanjiang Basins in NE China are analyzed in order to reveal palaeowildfire events and palaeoclimate variations. Although huminite is the dominant maceral group in the studied basins, the inertinite group, as a byproduct of palaeowildfires, makes up a considerable proportion. Occurrence of inertinite macerals indicates that wildfires were widespread and frequent,and supports the opinion that the Early Cretaceous was a "high-fire" interval. Inertinite contents vary from 0.2% to 85.0%, mostly within the range of 10%–45%, and a model-based calculation suggests that the atmospheric oxygen levels during the Aptian and Albian(Early Cretaceous) were around 24.7% and 25.3% respectively. Frequent fire activity during Early Cretaceous has been previously related to higher atmospheric oxygen concentrations. The inertinite reflectance, ranging from 0.58%Ro to 2.00%Ro, indicates that the palaeowildfire in the Early Cretaceous was dominated by ground fires, partially reaching-surface fires. These results further support that the Cretaceous earliest angiosperms from NE China were growing in elevated O2 conditions compared to the present day.

SHRIMP zircon U-Pb ages from coal beds across the Permian-Triassic boundary, eastern Yunnan, southwestern China

The first SHRIMP zircon U e Pb ages from coal beds close to the end-Permian mass extinction are reported from the C_1 coal seam in the Yantang Mine in Laibin Town, Xuanwei County, eastern Yunnan Province.Zircons were extracted from kaolinite claystone layers, defined as tonsteins(volcanic ash deposits), in the subseam B_1 and B_3 of the coal seam C_1.The U-Pb ages are 252.0 ± 2.3 Ma and 250.3 ± 2.1 Ma for the sub-seam B_1 and B_3, respectively. Within analytical uncertainties, these U-Pb ages include the time period of the onset of the mass extinction at 251.941 ± 0.037 Ma, which was obtained from the marine Meishan section in Zhejiang Province, ~1600 km away from the Yantang Mine. These new ages represent not only the first and closest ages to the PTB mass extinction in terrestrial coal beds, but also ages from the nearest site to the Emeishan volcanoes investigated so far. Therefore these new data provide the most accurate stratigraphic horizon of terrestrial facies of the end-Permian extinction in South China. The Emeishan volcanoes were likely the source of volcanic ash in the coal seams at the Xuanwei County and broader areas in South China. Furthermore, the minerals and geochemistry characteristics of the C_1 coal seam also implied the influences of contemporaneous volcanic activities.

Application of channel-belt scaling relationship to Middle Jurassic source-to-sink system in the Saishiteng area of the northern Qaidam Basin,NW China

Palaeodrainage basin,as an important component of the source-to-sink system,contains critical information on provenance and palaeoenvironment.Previous studies indicate that the scaling relationships of source-to-sink system components generally follow power laws,and channel-belt thickness represents a reliable first-order proxy for the drainage area.In this study,a database of borehole cores and geophysical well logs of the Jurassic coal measures from Saishiteng area in the northern Qaidam Basin was used to reconstruct the palaeogeography,and to identify single-story channel-belts.Three palaeochannels,namely,River A,River B and River C,were identified which were persistent throughout the Dameigou and Shimengou Formations during the Middle Jurassic.The mean channel-belt thicknesses of River A,River B and River C in the Dameigou Formation were 9.8 m,8.9 m and 7.9 m,respectively,and those in the Shimengou Formation were 7.4 m,6.2 m and 5.4 m,respectively.We estimate the drainage area of three major rivers by using scaling relationships between drainage area and channel-belt thickness.The drainage areas of River A,River B and River C in the Dameigou Formation were 63.0×10~3 km^2,50.1×10~3 km^2 and 37.7×10~3 km^2,respectively,and those in the Shimengou Formation were 32.3×10~3 km^2,21.2×10~3 km^2 and15.3×10~3 km^2,respectively.The drainage basin lengths of River A,River B and River C in the Dameigou Formation were 300.4 km,239 km and 180.2 km,respectively,and those in the Shimengou Formation were 154.3 km,101.3 km and 73.1 km,respectively.For both the Dameigou and Shimengou Formations,River A showed the largest scale,followed by River B and River C succeedingly,which was mainly determined by the stretch direction of provenance in the southern Qilian Mountains.The variations of channel-belt thickness,drainage area and drainage basin length between Dameigou and Shimengou Formations are the response of source-to-sink system to the transformation from extension to compression depression during the Middle Jurassic in the northern Qaidam Basin.

Using geophysical logs to identify Milankovitch cycles and to calculate net primary productivity(NPP) of the Late Permian coals,western Guizhou,China

Milankovitch periodicities of 123 kyr(eccentricity), 35.6 kyr(obliquity), and 21.2 kyr(precession) were identified in geophysical logs of three Late Permian coals: 17#, 18#, and 17 + 18#, from the Songhe mining area in western Guizhou Province. Based on the astronomic temporal framework, the periods of deposition of the 17#(5.6 m), 18#(6.4 m), and 17 + 18#(5.4 m) coals were constrained to 140.8–119.8 kyr, 160–136.2 kyr, and 135–114.9 kyr,respectively. The overall depositional period of the 18# coal of 160–136.2 kyr was further subdivided using the wavelet analysis method, into short and precise periods corresponding to the Milankovitch periodicities. It includes one eccentricity periodicity(123 kyr), three obliquity periodicities(35.6 kyr), and five precession periodicities(21.2 kyr). Different thicknesses of the subdivided coal sections, equivalent to the same time span of deposition, indicate different rates of coal deposition, i.e., thicker sections imply higher rates while the thinner sections represent lower rates. The combination of the measured average carbon concentration with the density of the coals gave rise to long-term average values of carbon accumulation rates for the Late Permian coals, in the range of 42.4–50.6 g?C?m^(-2)?a^(-1). This range corresponds to the long-term average carbon accumulation rates for the initial peat in the range of 60.6–72.3 g?C?m^(-2)?a^(-1). Based on the known quantitative relation between net primary productivity(NPP)values and long-term average carbon accumulation rates for the Holocene tropical peatlands, the range of NPP values for the Late Permian tropical peatlands was estimated as 242.4–433.8 g?C?m^(-2)?a^(-1).A comparison of existing information about peatland NPP levels of various ages and latitudes indicated that when conditions of high rain and high humidity prevail in the palaeo-peatland at given latitude, the NPP rates will vary with changes in atmospheric concentration of CO_2 and O_2. This relationship may lead to the use of coals as an indicator for the concentration of these gases(CO_2 and O_2) in the contemporaneous atmosphere encompassing the long records of coal deposition.

Continental chemical weathering during the Early Cretaceous Oceanic Anoxic Event(OAE1b): a case study from the Fuxin fluvio-lacustrine basin, Liaoning Province,NE China

This study focuses on Early Cretaceous mudstones from the Shahai and Fuxin formations in the Fuxin continental basin. We analyse chemical weathering, land surface temperatures and palaeoclimates based on chemical weathering indices, and emphasize the implications of continental chemical weathering on nutrient fluxes into lakes and oceans.According to Cr and Ni abundance, Al2O3-TiO2, La/Sc-Th/Co and V-Ni-Th×10 plots, as well as rare earth element(REE)analysis, mudstone samples from the Shahai and Fuxin formations were derived from the same type of provenance comprising mainly felsic igneous rocks. Chemical weathering trends reflected by the Chemical Index of Alteration(CIA),Weathering Index of Parker(WIP) and the Mafic Index of Alteration for Oxidative weathering environments(MIA(O)) are consistent with each other and allow the geological succession to be divided into four stages. Land surface temperatures of the Shahai and Fuxin formations are estimated based on the linear relationship of CIA to temperature,and also can be divided into four stages consistent with those determined from chemical weathering trends. During Stage A(early part of the late Aptian) chemical weathering and land surface temperatures were relatively low and showed characteristic high fluctuations, while Stage B(latest Aptian) represented a transitional period where weathering rates and temperatures increased, and high amplitude fluctuations continued. Conditions changed markedly in Stage C(early Albian) with very high and stable weathering, and warm, humid climates, while in Stage D(middle and late Albian) conditions returned to low chemical weathering and land surface temperatures. These stages of chemical weathering and land surface temperature fluctuations represent responses to global climate fluctuations during the Early Cretaceous, with the early Albian high weathering intensities and warm, humid climates combining to create high nutrient levels that would have flushed through rivers into lakes and ultimately oceans. This correlates stratigraphically with the development of Early Cretaceous black shales during Ocean Anoxic Event 1 b, showing the importance of continental weathering regimes as a causal mechanism for lake and ocean anoxia.

A toxicological investigation of the air quality in a moxibustion treatment room as measured through particulate concentration and oxidative capacity

Background: Moxibustion is a traditional Chinese medicine(TCM) therapy in which mugwort(Artemisia vulgaris) floss is burned to warm and stimulate acupoints. The modality has been used traditionally for thousands of years. However, smoke-related safety issues have recently been of concern, and little is known about moxa smoke and air quality in the clinical moxibustion environment.Objective: To assess the air quality in a typical moxibustion treatment room using particulate matter(PM) concentration and DNA oxidative damage at PM10.Methods: The study was conducted in August and November to December, 2011, at a TCM clinic in Beijing, China, in a moxibustion treatment room. A moxa-free treatment room and the outdoor area adjacent to the clinic were used as controls. PM10 concentrations were monitored with a portable digital dust indicator. The oxidative capacity of whole and water-soluble fractions of PM10 were detected using plasmid DNA assay. The results were shown as TD40 values; that is, the amount of PM10 that causes plasmid DNA damage of 40%.Results: Average PM10 concentrations in the moxibustion room were 2.56 mg m^(-3) in summer and 2.78 mg m^(-3) in winter, much higher than at control sites. For whole and water-soluble fractional PM10, the average summer TD40 values collected in the moxibustion room were 791.67 μg ml^(-1) and 876.33 μg ml^(-1) respectively, and the winter values were 779.86 μg ml^(-1) and 879.57 μg ml^(-1). These results of winter samples were significantly higher(p < 0.001) than the corresponding results from control sites. However, there was no statistical difference(p = 0.06)between the TD40 values of both the whole and water-soluble fractional PM10 from the moxibustion treatment room, while differences were significant in the general treatment room(p = 0.025) and at the outdoor site(P < 0.001).Conclusion: Our study shows that moxa smoke increases PM10 concentration. However, the oxidative capacity of PM10 in the moxibustion room was much lower than that at control sites with the same particulate burden, and the bioactivity at that site was mainly from the watersoluble fraction, another difference from the controls. This unexpected bioactivity is assumed to relate to the low toxicity of moxa smoke or to its proven antioxidant activity. Overall, further research is needed.

Characteristics and evolution of inertinite abundance and atmospheric pO_(2) during China's coal-forming periods

Coal, especially the inertinite in it, is highly sensitive to climate changes, showing an obvious response to paleoclimate conditions, in particular, to paleo-oxygen concentration(pO_2 ). In this study, the inertinite abundance data of typical coal-forming periods in China were systematically collected and analyzed. Its characteristics and control factors were studied, and its evolution was established. Based on inertinite abundance data, pO_2 evolution curves of various coal-forming periods in China were established, which fluctuated between 15% and 30% during the entire Phanerozoic. The inertinite abundance in coal deposits during Paleozoic in China was basically consistent with that of other areas of the world, while it was quite different globally from the Mesozoic to the Cenozoic. The results show that the inertinite abundance in coal deposits is controlled by pO_2 and other factors including climatic zones, plant differentiation, sedimentary environments, and tectonic activities. The inertinite abundance in coal deposits in China during the Jurassic was high, suggesting dry paleoclimate of inland China.