The Late Triassic Carnian Pluvial Episode (CPE; ca. 234–232 Ma) was characterized by dramatic global temperature and humidity increases, which in many terrestrial settings was accompanied by changes from arid to humid vegetation types. This study reviews current evidence of terrestrial floral composition and distribution during the CPE and analyzes spatial and temporal variation with relation to potential environmental driving mechanisms. Available evidence suggests the CPE was a globally significant event that triggered significant increases in the abundance of ferns and hygrophytes in terrestrial floras and freshwater algae in fluvial and lacustrine settings. These changes ended a long interval of relatively arid terrestrial climatic conditions since the Early Triassic and are linked temporally with eruptions of the oceanic plateau Wrangellia Large Igneous Province (LIP). The massive release of greenhouse gasses including isotopically light CO2 during 3–4 distinct pulses of Wrangellia volcanism appears to have been the main driver of CPE climate change. Each pulse enhanced global atmospheric circulation and the hydrological cycle and resulted in changes from arid to humid conditions that affected floral abundance and composition. Higher terrestrial primary productivity in humid phases facilitated increased burial of terrestrial organic carbon and led to the recommencement of peat accumulation, ending the coal gap that had persisted since the Earliest Triassic times. Enhanced movement of carbon from the atmosphere through the biosphere into the geosphere may have counteracted the warming effects of Wrangellia volcanic greenhouse gas emissions and ultimately led to the return of a steady climate state that terminated the warm and humid conditions of the CPE.

/pdf/floral-response-to-the-late-triassic-carnian-pluvial-episode-2q82j8a0.pdf

Floral response to the Late Triassic Carnian Pluvial Episode

The Early Jurassic Jenkyns Event (or Toarcian Oceanic Anoxic Event T-OAE) was an episode of global warming and C-cycle perturbation that affected both marine and terrestrial ecosystems, but the interplay between climate change and vegetation is not established in detail from sections outside of Europe. Here, abundance changes in spore-pollen assemblages from the lacustrine Anya succession in the Ordos Basin (North China) reveal a unique record of vegetation dynamics during the Jenkyns Event. Plant communities responded to the event with biodiversity losses and the reorganization of gymnosperm-dominated forests. Community-level shifts are observed from the Pliensbachian–Toarcian boundary, but the onset of the negative carbon excursion (NCIE) that marks the event is coeval with the most significant turnover: a switch from a high-diversity vegetation with conifers, seed ferns, cycads, bennettites and ferns to drought-adapted low-diversity flora with Cheirolepidiaceae. The demise of forests and lowland mire biomes resulted in deforestation with increased weathering and soil erosion that exacerbated the terrestrial ecosystem crisis already under stress from rising temperatures. Terrestrial recovery was initiated before the end of the Jenkyns Event with the resurgence of pioneer ferns and lycopsids that colonized disturbed habitats. Plant assemblages signal aridification at the onset of the event with frequent climatic oscillations and extreme weather patterns during the event itself. The main NCIE phase was preceded by a short-lived cooling phase in the earliest Toarcian. In the aftermath of the NCIE, Cheirolepidiaceae forests declined and a more stable biome developed with seed ferns and various conifers. This was contemporaneous with delta development and shallowing of the lake surrounded by lowland mires with ferns, clubmosses and horsetails. Comparison of floral patterns across the Jenkyns Event show that, although Cheirolepidiaceae dominated the event globally, there were differences in vegetation response between coastal and inland areas, and recovery patterns might differ regionally. 

Vegetation response to climate change during an Early Jurassic hyperthermal event (Jenkyns Event) from Northern China (Ordos Basin)

The arid climate of the Late Triassic was interrupted by a particularly humid episode known as the Carnian Pluvial Episode (CPE; ca. 234–232 million years ago). The CPE is often linked to eruptions in the Wrangellia Large Igneous Province (LIP), and is assumed to have led to global warming, enhanced weathering, water deoxygenation, and biotic changes. However, direct evidence for a temporal link between volcanic activity and chemical weathering has not yet been established due to the lack of comprehensive records across the CPE. In this study, geochemical and mineralogical analyses are applied to a lacustrine stratigraphic succession of the Jiyuan Basin (North China) that captures the CPE in high resolution. We identify four distinct pulses of enhanced continental chemical weathering characterized by elevated Chemical Index of Alteration values and kaolinite contents. These peaks in continental weathering coincide with Hg/TOC enrichments and negative organic carbon isotope excursions that mark four short (∼400 kyr) but intense pulses of Wrangellia LIP volcanism. In combination with signs of increased humidity, our findings provide direct and independent evidence that Wrangellia LIP eruptions significantly altered CPE chemical weathering rates in response to global warming and wetting. The lake experienced eutrophication and water deoxygenation after each volcanic pulse but the swift recovery of carbon isotopes suggests that the system rapidly returned to conditions prior to the volcanic perturbation. Organic carbon burial facilitated by widespread dysoxic and anoxic waters, and CO2 consumption via enhanced weathering likely played crucial roles in the rapid climatic recovery after each volcanic pulse. 

Four volcanically driven climatic perturbations led to enhanced continental weathering during the Late Triassic Carnian Pluvial Episode

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials. 

Piezoelectric Scaffolds as Smart Materials for Bone Tissue Engineering

The Qaidam Basin is a prominent oil and gas exploration and production base of NW China’s Jurassic coal-bearing strata. Coal-bearing mudstones are important source rocks for unconventional reservoirs and can record valuable paleoenvironment and paleoclimate information. Here, geochemical analysis including total organic carbon (TOC), total sulfur, organic carbon isotopic composition, rock pyrolysis, X-ray diffraction, and major and trace elements were carried out on mudstone samples from the Middle Jurassic coal-bearing strata of the Dameigou section in the Qaidam Basin to reveal the paleoclimatic and paleoenvironmental conditions during the deposition of the strata and their controls on organic matter accumulation. Results show that the Middle Jurassic Dameigou and Shimengou formations include three significant stages based on their average TOC values of (3.32%, Stage I; 0.87%, Stage II; and 4.42%, Stage III) from the bottom to the top. The organic matter in mudstones in Stages I and II are mainly derived from terrestrial higher plants, while the organic matter has mixed sources of higher plant debris and lower aquatic organisms in Stage III. Paleoclimate parameters indicate that the mudstones in Stage I were deposited under humid and warm conditions, while the climate in Stage II changed to semiarid and warm conditions before turning dry and hot in Stage III. The varying paleoenvironmental characteristics under different paleoclimatic conditions have also been reconstructed. Our results suggest that the accumulation of organic matter in Stages I and II was primarily controlled by redox conditions, while paleoproductivity is the major controlling factor for organic matter accumulation in Stage III.

Geochemical Characteristics of the Middle Jurassic Coal-Bearing Mudstones in the Dameigou Area (Qaidam Basin, NW China): Implications for Paleoclimate, Paleoenvironment, and Organic Matter Accumulation

Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai-Tibet Plateau, China

Bone repair and regeneration have aroused widespread interest due to their potential usefulness in cases when bone self-healing is insufficient. In this work, a Poly(vinylidene fluoride-trifluoroethylene)-coated-Poly methyl methacrylate Janus membrane was prepared, where a P(VDF-TrFE) coating on a PMMA film serves as Janus-A to mediate cell growth behavior, owing to its electroactivity, and the PMMA film serves as Janus-B to inhibit soft-tissue growth. A P(VDF-TrFE) coating separated from the substrate was put above the PMMA film before the PMMA film had dried completely, and a Janus membrane formed because of the flowability and adhesion of the nonvolatile PMMA solution. Their bonding could withstand the pressure of the body fluids in the shear direction. Various crystallization substrates were also applied to modulate the P(VDF-TrFE) coating’s surface potentials, as the surface potential would further affect cellular response. It was also found that the responses of the bone marrow mesenchymal stem cells (BMSCs) and bone marrow macrophages (BMDMs) could be adjusted through surface potential modification. Such a Janus membrane could potentially be applied to a biological environment with the effect of both guiding bone regeneration and preventing soft tissue adhesion.

https://www.mdpi.com/2079-6412/12/12/1947/pdf?version=1670837762

A Facile Synthesis of P(VDF-TrFE)-Coated-PMMA Janus Membranes for Guided Bone Regeneration

The formation and accumulation of lacustrine organic-rich shales are strongly related to palaeoclimate and palaeoenvironmental conditions. Middle Jurassic organic-rich lacustrine shales in the Qaidam Basin, NW China, are important source rocks for unconventional oil and gas exploration, but factors controlling their organic matter (OM) abundance and preservation are unclear. To understand how palaeoclimate and palaeoenvironmental conditions influenced depositional processes and elucidate the factors controlling OM accumulation of lacustrine organic-rich shales, we investigated total organic carbon (TOC), mineral compositions, and element geochemistry the Shale Member of the Middle Jurassic (J2s2) Shimengou Formation from the Yuqia Coalfield in the Qaidam Basin. From the bottom to the top, the Shale Member includes three significant stages based on their average TOC values of 5.45% (Stage I), 9.90% (Stage II), and 1.10% (Stage III). Paleoclimate proxies including C-values and Rb/Sr ratios indicate that in Stage I the lake developed under warm and humid conditions, while in Stage II climate changed to hot and arid/semiarid conditions before returning to warm and humid climates in Stage III. Correlation analysis among proxies for palaeoclimate, terrestrial influx (Al2O3 and TiO2 contents), sedimentation rate ((La/Yb) N ratios), palaeosalinity (Sr/Ba ratios and B/Ga ratios), palaeoproductivity (P/Ti ratios and Sibio contents), redox conditions (Corg/P ratios), and TOC values revealed that palaeoclimate had little direct impact on OM accumulation, with palaeoenvironmental conditions the main controlling factor for OM accumulation. OM accumulation in Stage I was primarily controlled by redox conditions, followed by palaeoproductivity, terrigenous influx, and sedimentation rate. In Stage II, high palaeoproductivity and anoxic bottom water conditions controlled OM accumulation, resulting in the deposition of oil shales with abundant hydrocarbon potential. In Stage III, poor OM preservation related to oxic redox condition was the primary controlling factor for OM accumulation. We suggest that variations in lake palaeoenvironments induced by palaeoclimate change controlled OM accumulation and petroleum potential. 

Palaeoclimatic influence on lake palaeoenvironment and organic matter accumulation in the Middle Jurassic Shimengou formation (Qaidam basin, NW China)

The Qaidam Basin is one of the major coal-bearing basins in northeastern China with the coal seams mainly preserved in the Lower–Middle Jurassic. The Middle Jurassic sedimentary environment, sequence stratigraphy, paleoclimate, and coal accumulation in the Qaidam Basin have been extensively studied, while the sedimentary characteristics and depositional evolution of the Lower Jurassic coal-bearing series are less well known. We systematically analysed the facies association, depositional system, basin evolution, and coal accumulation of the Early Jurassic Pliensbachian-aged coal-bearing series from the Dameigou section in the northern Qaidam Basin. Five lithological types have been identified, ranging from conglomerates, sandstones, siltstones, and mudstones to combustible organic rocks, which were further subdivided into 12 lithofacies. These lithofacies were grouped into four facies associations, representing the braided fluvial, meandering fluvial, lacustrine, and meandering fluvial-lacustrine transition deposits, respectively. The Pliensbachian Stage mainly developed as a fluvial-lacustrine depositional system and an evolution history from braided fluvial to meandering fluvial, then to lacustrine, and finally back to meandering fluvial was reconstructed. We suggest that climate change is the major controlling factor for depositional evolution during the Pliensbachian. The transition of the depositional environment from fluvial to lacustrine in the study area can be attributed to the rapid climatic change induced by volcanism at this interval. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/gj.4819

Evolution of depositional environment of the Pliensbachian Stage (Lower Jurassic) coal‐bearing series in the Qaidam Basin, NW China

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Middle Jurassic terrestrial environmental and floral changes linked to volcanism: Evidence from the Qinghai-Tibet Plateau, China

A Facile Synthesis of P(VDF-TrFE)-Coated-PMMA Janus Membranes for Guided Bone Regeneration

Palaeoclimatic influence on lake palaeoenvironment and organic matter accumulation in the Middle Jurassic Shimengou formation (Qaidam basin, NW China)

Evolution of depositional environment of the Pliensbachian Stage (Lower Jurassic) coal‐bearing series in the Qaidam Basin, NW China