In the margins of the major sedimentary basins in northern and western China,burnt rocks formed from the spontaneous combustion of coal seams are commonly found,resulting in special burnt rock landform. This landform is widely distributed in China,commonly with bright colore. However,its scientific and tourist values have been hardly focused on in literature. Few studies have involved the tourism development of such burnt rock landforms in China. Based on field investigations of outcrop sections,this study classifies these landforms into: burnt hilly landforms(including burnt red hilly landform,burnt colorful hilly landform and peak-covered landform of burnt rocks), erosional landform of burnt rocks(including gully landform,steep cliff landforms), collapse landform and loess-covering burnt rock landform according to the process of coal spontaneous combustion,landform genesis,spatial distribution and color of the burnt rocks. Among them,hilly and erosional landforms are commonly seen,while collapse landform mainly exists in areas where underground coal seams are burning. Loess-covering burnt rock landform formed with the Quaternary loess covering the burnt rocks. The formation of various burnt rock landforms is mainly controlled by such factors as coal seam thickness,stratum occurrence,tectonic movement,river erosion and paleoclimate. Burnt rock landforms should be given more attention due to its scientific value and tourism exploitation value. These burnt rock landforms have significant scientific and tourism development values and deserve appropriate attention.

The Eocene represents a critical interval for understanding the evolution of the global carbon cycle. During this period,Northeast China experienced significant fluctuations in atmospheric CO₂ concentrations,ranging from 454 to 1861 μmol/mol. While these variations underscore the region’s importance in carbon cycle research,current understanding of carbon cycling in terrestrial lake systems remains limited. Most studies have focused on modern lakes since the Pleistocene,leaving a notable gap in systematic research on carbon cycling in ancient lacustrine basins such as those of the Eocene. This study integrates multiple geochemical proxies with a quantitative carbon source-sink flux model to reconstruct organic carbon burial and carbon emissions in the Yilan paleo-lake basin during the Early Eocene Climatic Optimum(EECO)and the Middle Eocene Climatic Optimum(MECO)events. The findings reveal that the Yilan Basin exhibited peak primary productivity,organic carbon burial rates,and CO₂ emissions from fossil carbon oxidation during the EECO. Despite substantial carbon release during these events,the net carbon fixed via photosynthesis(reaching 241650 Mt during the EECO)and the resulting buried organic carbon(~4028 Mt during the EECO)significantly exceeded CO₂ emissions from fossil carbon oxidation(~1448 Mt during the EECO). Therefore,the Yilan Basin functioned as a net carbon sink in Northeast China during the EECO and MECO,serving as an important natural regulator of regional climate.

Shidao is the highest-altitude island in the South China Sea and a severely karst-affected area with weakly consolidated high beachrocks. It is also a challenging region for ecological protection and restoration engineering. This paper reports the findings of over a decade of field investigations,highlighting the Old Dragon Head(Laolongtou),Root Pipe Stone,and Wedge-shaped Prograding Stratification as the three top ecological landscapes and precious geological heritage resources in the Xisha Islands. The Laolongtou is the only naturally formed dragon-shaped stone in the world and a symbol of the military and civilian population’s dragon totem in the Xisha Islands. However,the rapid and destructive evolution of karstification caused by seven natural forces,including wave erosion,tidal erosion,wind erosion,high temperature,high humidity,high salinity,and freshwater leaching,as well as human activities,is alarming. Although this is an inevitable natural process,it is a tragedy for the top ecological landscapes. This paper briefly describes the characteristics of the seven natural forces of karstification and proposes the use of iron-aluminate cement-based materials with low alkalinity(pH value is 10~11),resistance to seawater corrosion,and increasing strength upon immersion(corrosion resistance coefficient>1),along with unique engineering techniques,to achieve the goal of external toughening and in-situ strengthening of the rock mass,ensuring the sustainable inheritance of the Laolongtou.

The Paleozoic plant terrestrialization(PPT)represents a pivotal point in the evolutionary history of life on Earth. This process not only reshaped surficial geomorphological landscapes but also exerted on others biotic evolution throughout the Phanerozoic. Until now,how benthic animals respond to PPT across different depositional environments,as well as their roles in the construction of benthic ecosystems,have remained insufficiently understood. Based on the compilation and synthesis of a global trace fossil dataset,this study establishes a time-depositional environment analytical framework. Within this framework,we systematically compare the evolutionary patterns of ichnodiversity,ichnodisparity,ichnotiering,and benthic ecosystem engineering across transitional coastal,fluvial,and lacustrine settings during the process of PPT. Furthermore,we quantitatively assess the behavioral responses of benthic animals to PPT. The results show that from the Cambrian to the Permian,the behavioral evolution of benthic animals exhibits pronounced time-limited and heterogeneity. During the Ordovician,benthic animals in transitional coastal environments had already begun to show initial responses to PPT,whereas those in fluvial and lacustrine environments display a clear temporal lag. This discrepancy is closely associated with the development of plant root systems,the progression of PPT,and subsequent forest expansion. Overall,with the progressive improvement of substrate stability and organic matter availability in both continental and transitional settings driven by terrestrial plants,benthic animals gradually expanded their ecospace utilization,accompanied by increased behavioral complexity and enhanced ecosystem engineering. In turn,benthic animals exerted a positive feedback on PPT through sediment reworking and the modulation of matter and energy fluxes. In addition to the influence of terrestrial vegetation,environmental factors such as climate change and tectonic activity,and sea-level fluctuations also played significant roles in shaping benthic evolutionary trajectories. This study provides a novel ichnological perspective for understanding Paleozoic ecosystem evolution and biotic-sediment interactions.

Tubiphytes is a taxonomically enigmatic organism with a broad geographic distribution and an extensive stratigraphic range,documented widely in reef facies from the Late Paleozoic to the Mesozoic,making its study of significant paleoecological importance. Abundant Tubiphytes fossils have been found in the Late Pennsylvanian strata of Guizhou Province,South China. Specifically,Tubiphytes-dominated bioherms are well-developed in the Gzhelian strata of the Houchang area,southern Guizhou,providing an excellent research object for investigating the palaeoecology of this enigmatic taxon. Palaeontological analyses indicate that Tubiphytes obscurus obscurus Maslov is the dominant species in the study area,and its microstructure and paleobiological characteristics indicates that this taxon functioned as an aggregate binder and encruster,involving symbiotic associations among foraminifera and microbial communities. Quantitative analyses show that in the Tubiphytes reefs of the study area,solitary Tubiphytes exhibit a symbiotic relationship with Archaeolithoporella and the colonial coral Ivanovia cf. manchurica,while massive Tubiphytes compete with organisms such as the colonial coral Ivanovia cf. manchurica and phylloid algae. Furthermore,Tubiphytes forms micro-encrusting communities with Archaeolithoporella, and—combined with successive generations of marine cement—contributes critically to the development of the reef’s microframework,thereby assuming a primary role in reef construction. These Tubiphytes-dominated micro-encrusting communities repeatedly formed reefs in environments lacking metazoans and constitute a key component of the expansive reef systems that flourished along the Paleo-Tethyan margin.

The Late Triassic Carnian Pluvial Episode(CPE,~234-232 Ma)is characterized by a sharp increase in global temperature and humidity,accompanied by significant changes in marine and terrestrial ecosystems,and is associated with the eruptions of the Wrangellia Large Igneous Province(LIP). Much of the current research on CPE has focused on marine strata with well-constrained stratigraphy,while research on the response processes of terrestrial ecosystems to CPE has been limited. Here,we review the status of terrestrial environmental,climatic,and plant changes during the CPE and explore its potential driving mechanisms. The evidence of multiple nearly synchronous negative carbon isotope excursions(CIEs),mercury(Hg)enrichment anomalies(peaks in the Hg/TOC ratio),and Hg isotopes provides direct evidence that the Wrangellia LIP was a driving factor for the significant changes in terrestrial environment,climate,and biology during the CPE. The eruption of the Wrangellia LIP released a large amount of CO₂,triggering global warming. This has led to enhanced atmospheric circulation and hydrological cycles,promoting increased global rainfall and a shift in climatic conditions from relatively warm and dry to relatively warm and humid. These conditions have resulted in the extensive development of terrestrial deltas and swamps,the rise of lake levels,the intensification of chemical weathering,the increase of hygrophytic plants and freshwater algae,and the re-emergence of global coal accumulation,as well as the origin and radiation of dinosaurs,coniferous plants,insects,crocodiles,turtles,and mammals. Terrestrial weathering,the expansion of surface water systems,and an increase in hygrophytic plants and freshwater algae have driven a significant rise in the amount of terrestrial organic carbon buried,contributing to the resurgence of global coal accumulation. The increase in the amount of organic carbon buried and the re-emergence of global coal accumulation have created negative feedback on the improvement in global atmospheric conditions. This can counteract the greenhouse effect caused by the release of greenhouse gases from the Wrangellia LIP,facilitate the gradual stabilization of the environment and climate during the CPE,and ultimately lead to the termination of the CPE. These results suggest that LIP can occur in multiple pulse forms and have a powerful ability to alter the carbon cycle,trigger environmental and climatic changes,and drive macroevolution of organisms. On the other hand,global coal accumulation plays a crucial role in climate stability.

The Devonian strata in the northern Guangdong Province are widely distributed and well-developed,with abundant fossil data. Through comprehensive stratigraphic comparisons and analyses of lithostratigraphy,biostratigraphy,sequence stratigraphy and event stratigraphy in the research area,and based on a measured section in the Nangang Village,Liannan County(four sedimentary facies,three biological zones and eight stratigraphic sequences),three distinct evolutionary stages of Devonian sedimentary paleogeography are recovered(Middle Devonian Givetian,Late Devonian Frasnian and Famennian). Under the opening and expansion of the Qinfang Trough,the northern Guangdong Province was gradually transgressed,forming a platform basin intertwined with a trough basin. It reached the largest ocean basin in the late Frasnian stage,and began to gradually recede during the Famennian stage. The paleogeographic feature affected the paleontological distribution and spatiotemporal migration,such that the transition from the coral-stromatoporoid reef community(Givetian),stromatoporoid reef community(Frasnian)and fungal-algae reef community(Famennian)was clear in the Nangang Village,Liannan County. According to Devonian regional paleogeographical characteristics,reef communities,tectonic and climatic background,the tectonic event was the dominant factor for the biological and geological environment,especially during the Late Devonian F-F event.

The Cretaceous period was characterized by numerous globally significant tectonic and climatic events that are well preserved in the Liupanshan Basin,where the exceptionally continuous and widely distributed Cretaceous strata,predominantly composed of fluvial-lacustrine deposits,host exquisitely preserved Lycoptera fossils,making this basin an ideal site for studying paleoclimatic and paleoenvironmental changes during the Cretaceous. Through an integrated approach combining sedimentology,stratigraphy,paleontology,and geochemistry,this study investigates the Liwaxia Formation in the Liupanshan Basin,employing organic carbon isotope(${\delta }^{13}{\mathrm{C}}_{\mathrm{o}\mathrm{r}\mathrm{g}}$)analysis,major and trace element geochemistry,and X-ray fluorescence(XRF)to examine the paleoclimate and paleoenvironment of Lycoptera-bearing intervals and to assess their relationship to global events. Geochemical results reveal three distinct ${\delta }^{13}{\mathrm{C}}_{\mathrm{o}\mathrm{r}\mathrm{g}}$ evolutionary stages: a significant negative excursion(from-30.21‰ to-27.19‰,amplitude 3.02‰)in intervals B3-B7,a sharp positive shift(from-28.05‰ to-24.13‰,amplitude 3.92‰)in intervals B11-B15,followed by an oscillatory positive trend in intervals B17-B25. The fossil-bearing horizons exhibit notable geochemical anomalies,including marked fluctuations in major elements(Ca,Mg)and trace elements(Sr,Th)relative to adjacent strata,while micro-XRF analysis of fish fossil bones reveals marked enrichments of heavy metals and toxic elements(Mn,Cr,As,S). These Lycoptera-bearing strata record lacustrine environmental conditions during the C3 stage of Oceanic Anoxic Event 1a(OAE1a),characterized by the diagnostic ${\delta }^{13}{\mathrm{C}}_{\mathrm{o}\mathrm{r}\mathrm{g}}$ negative excursion marking OAE1a onset and reflecting hot,arid,hypersaline,and anoxic conditions in the Liupanshan Basin. The mass mortality of Lycoptera likely resulted from the combined effects of persistent bottom-water anoxia caused by Early Cretaceous volcanic-induced greenhouse conditions and the toxicological impact of heavy metals and toxic elements enriched in volcanic ash. This research not only sheds light on the response mechanisms of the paleoclimate and paleoenvironment within the Liupanshan Basin to global events,but also provides crucial biogeochemical evidence and paleontological records essential for understanding the climatic and environmental evolution of Cretaceous terrestrial ecosystems and associated biological extinction events.

Ecological evolution varied significantly across different water depth during the Permian-Triassic mass extinction. Shallow-water carbonate platform environments,characterized by low ambient water depth,hosted the majority of benthic organisms and consequently exhibited heightened sensitivity to environmental changes. As such,they provide critical insights into marine ecosystem evolution under disaster scenarios. Although middle to deep-water settings have been extensively studied,research on shallow-marine environments remains limited. This paper focuses on the newly identified Panjiazhuang section,a shallow-water carbonate platform succession in the Changxing area of Zhejiang Province,and integrates sedimentological,paleontological,and isotopic geochemical analyses to reconstruct ecosystem evolution across the Permian-Triassic transition. In the Panjiazhuang section,a major extinction event is recorded at the top of the bioclastic limestone within the upper Permian Changxing Formation. This interval coincides with a distinct shift in microfacies—from foraminifera-and algae-rich bioclastic limestone to microbialite—indicating a rapid proliferation of cyanobacteria following the collapse of metazoan communities. Additionally,the inorganic carbon isotope exhibited a notable negative excursion during this time. The findings indicate that the ecosystem transition from bioclastic limestone to microbialite facies at the Paleozoic-Mesozoic boundary in the Panjiazhuang section represents a single-episode extinction process during the Permian-Triassic mass extinction event.

Paleoproterozoic stromatolites preserve structural features of microbial-environmental interactions,providing crucial biosedimentary records for deciphering the co-evolution of microbial communities and early environmental transitions. This study focuses on the branched columnar stromatolites from the basal Beidaxing Formation(~2.0 Ga)of the Hutuo Group in Wutai area,North China. Through macro-to-micro scale structural characterization,we elucidate their morphological features,controlling factors,and evolutionary significance. The results demonstrate that these stromatolites exhibit typical branched columnar structures,preserving well-defined alternating light-dark laminae(with light layers composed of microsparry or sparry dolomite and dark layers primarily of micritic dolomite), along with microclots and other microstructures. The alternating light-dark laminae reflect periodic microbial responses to environmental fluctuations,while the microclot structures originate from the synergistic interplay between microbial calcification and microbial mat degradation. Comprehensive analysis of both macroscopic morphological characteristics(including column inclination,diameter variations,and spatial distribution density)and sedimentological features(frequent scour surfaces,growth discontinuities,and abundant peloids)indicates their formation was governed by a dynamic equilibrium of key environmental factors: hydrodynamic conditions,growth space,light availability,and sediment input,etc. These stromatolites developed in moderate-to-high energy environments spanning the lower intertidal to shallow subtidal zones,characterized by low terrigenous input,moderate sedimentation rates,and frequent storm or tidal influences.