Cretaceous integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

The Cretaceous Period is a vital time interval in deciphering the evolutionary history of the Neo-Tethys Ocean and the convergence of different plates and blocks across the Qinghai-Tibetan Plateau.A detailed stratigraphic framework and paleogeographic patterns are the basis for understanding the evolution of the Neo-Tethys Ocean and the formation of the QinghaiTibetan Plateau.Here,the Cretaceous stratigraphy,biota,paleogeography,and major geological events in the Qinghai-Tibetan Plateau are analyzed to establish an integrative stratigraphic framework,reconstruct the paleogeography during the Cretaceous Period,and decode the history of the major geological events.The Cretaceous rocks of the Qinghai-Tibetan Plateau and its surrounding area are predominantly marine deposits,with a small amount of interbedded marine-terrestrial and terrestrial conponents.The Indus-Yarlung Tsangpo Suture Zone was responsible for the deposition of deep marine sediments dominated by ophiolite suites and radiolarian silicalite.To the south,the Tethys Himalayas and Indus Basin received marine sediments of varying depths and lithology;to the north,the Xigaze and Ladakh forearc basins are also filled with marine sediments.The Lhasa Block,Karakorum Block,western Tarim Basin,and West Burma block consist of shallow marine,interbedded marine-terrestrial,and terrestrial sediments.The Qiangtang Basin and other areas are dominated by terrestrial sedimentation.The Cretaceous strata of the Qinghai-Tibetan Plateau and its surrounding areas are widely distributed and diversified,with abundant foraminifera,calcareous nannofossils,radiolarians,ammonites,bivalves,and palynomorphs.On the basis of integrated lithostratigraphic,biostratigraphic,geochronologic,and chemostratigraphic analyses,we proposed herein a comprehensive stratigraphic framework for the Cretaceous Period of the eastern Neo-Tethys.By analyzing the Cretaceous biota of different biogeographic zones from eastern Neo-Tethys and its surrounding areas,we reconstructed the paleobiogeography of different periods of eastern NeoTethys.The Cretaceous paleogeographic evolution of the Qinghai-Tibetan Plateau and its surrounding areas can be divided into three phases:(1)gradual breakup of the Indian Plate from the Australia-Antarctica continent and the early collision phase of the Lhasa-Qiangtang blocks(145-125 Ma);(2)northward drift of the Indian Plate and the collision phase of the Lhasa-Qiangtang blocks(125-100 Ma);(3)rapid northward drift of the Indian Plate,formation of the Tarim-Tajik-Karakorum Bay,and early uplift of the Gangdise Mountains(100-66 Ma).The Indus-Tethys Himalayan biota underwent a transition from the cold-water type in the high latitudes of the southern hemisphere to the warm-water type near the equator from the Early Cretaceous to the MidCretaceous.The biodiversity and abundance of the eastern Neo-Tethys Ocean increased gradually in the Early Cretaceous,peaking in the Mid-Cretaceous,and decreased sharply during the late Late Cretaceous(late Maastrichtian).Along with the northward drift of the Indian Plate and subduction of the Neo-Tethys,the eastern Neo-Tethys and its surrounding areas experienced a series of major geological events,including the formation of the large igneous province,oceanic anoxia events,and mass extinction,etc.

Respiratory protein-driven selectivity during the Permian-Triassic mass extinction

Extinction selectivity determines the direction of macroevolution,especially during mass extinction;however,its driving mechanisms remain poorly understood.By investigating the physiological selectivity of marine animals during the Permian-Triassic mass extinction,we found that marine clades with lower O2-carrying capacity hemerythrin proteins and those relying on O2 diffusion experienced significantly greater extinction intensity and body-size reduction than those with higher O2-carrying capacity hemoglobin or hemocyanin proteins.Our findings suggest that animals with high O2-carrying capacity obtained the necessary O2 even under hypoxia and compensated for the increased energy requirements caused by ocean acidification,which enabled their survival during the Permian-Triassic mass extinction.Thus,high O2-carrying capacity may have been crucial for the transition from the Paleozoic to the Modern Evolutionary Fauna.

古生代-中生代之交的水循环演变及驱动机制

水循环是连接大气圈、水圈、岩石圈和生物圈的重要物质循环过程.本文根据地质记录和深时气候模拟等数据总结了古生代-中生代之交的水循环演变.结果表明,水循环在晚古生代、早中生代发生了重大变化:(1)地质记录恢复的气候带显示,当时全球的干旱带发生了明显扩张,蒸发岩面积从中-晚二叠世开始扩张,到早三叠世达到顶峰,中三叠世恢复至中-晚二叠世的水平,晚三叠-早侏罗世继续收缩;(2)全球年平均降水量在晚石炭、早侏罗世较高,中-晚二叠世和早三叠世较低,呈现为“V”字形变化,显示出一次重大的波动;(3)全球大陆的聚合可能导致泛大陆巨型陆面风和特提斯区域跨赤道风的形成,进而构成全球性的超级季风;(4)热带辐合带摆动的纬度位置在志留纪-石炭纪以及侏罗纪-现代较低,在二叠纪-三叠纪时期向高纬度大幅度漂移.根据事件发生的时间,这些水循环的重大变化与泛大陆的聚合、华力西造山、晚古生代冰期的结束以及大量碳释放和升温事件吻合,这些因素与当时的大气环流和水循环的变化存在密切联系:泛大陆的聚合改变了当时水储量的空间分布,同时改变了大气环流和“季风”,进而导致中-晚二叠世干旱带开始扩张,降水量减少;晚古生代末期华力西造山运动的减弱增强了热带辐合带的摆动,促进了超级季风的发展;碳释放驱动的升温事件改变了能量传输,影响了大气环流;同时植物面貌的转变影响了碳释放,进而影响水循环.由此可见,古生代-中生代之交水循环的强烈波动可能是该重大地质历史转折期岩石圈(地球深部过程)、大气圈(大气过程)、水圈(水循环)及生物圈(生命活动)相互作用的重要体现.

Phanerozoic oceanic and climatic perturbations in the context of Tethyan evolution

Climatic and environmental conditions play a pivotal role in the evolution of the biosphere,serving as the primary natural factors influencing biological evolution and the development of human civilization.The study of the evolution of Earth's habitability primarily revolves around the reconstruction of climatic and oceanic conditions in geohistorical periods,shedding light on their dynamic changes.This paper collates classic geological indicators and geochemical proxies associated with paleoclimatic and oceanic environmental conditions.The latest“big data”analyses and simulations made possible by the availability of previously unimagined massive datasets reveal several key findings:During the early Paleozoic,atmospheric oxygen levels were low,and widespread oceanic anoxia was prevalent;the Devonian era witnessed a greenhouse climate,followed by the Carboniferous ice age characterized by higher oceanic oxidation levels and alkalinity.The latest Paleozoic deglaciation occurred under high pCO_(2) conditions,extending into much of the Mesozoic and early Cenozoic,marked by multiple hyperthermal and anoxia expansion events,until the resurgence of global glaciation in the middle-late stages of the Cenozoic,ultimately bringing environmental and climatic conditions closer to modern levels.By correlating the aforementioned long-term trends with major geological events,we can delineate the co-evolution of paleoclimate and oceanic environments in tandem with the development of Tethys tectonics as follows.(1)During the Proto-Tethys stage,global paleo-elevations were relatively low,and atmospheric oxygen levels were also relatively modest.Despite the occurrence of significant tectonic movements that led to noticeable transgressive-regressive cycles,their effects on climate and oceanic environments were somewhat limited due to the relatively weak interactions.(2)The emergence of the Paleo-Tethys was a significant event that coincided with the formation of the supercontinent Pangaea.Intensive orogenic movements during this period increased the global land area and elevation.This,in turn,led to enhanced terrestrial weathering,which elevated sea surface productivity and resulted in massive nutrient input into the oceans.Consequently,this process contributed to the rise of oxygen levels in the atmosphere and a decrease in atmospheric pCO_(2).These changes are considered potential driving mechanisms for late Paleozoic glaciation and oceanic oxygenation.(3)The transition from the Paleo-Tethys to the Neo-Tethys was closely linked to the breakup of Pangaea.During this period,the terrestrial weathering processes were relatively weak due to decreased continental elevations.This resulted in a long-term greenhouse climate and intermittent global oceanic events,which were responses to the high atmospheric pCO_(2) levels during the Mesozoic and early Cenozoic eras.(4)The Neo-Tethys stage ended with the dramatic uplift of the Alps-Himalaya Mountain ranges due to the collision of India and Asia.This uplift had a profound global impact,significantly increasing continental elevations.As a result,weathering and carbon burial processes intensified,leading to a reduction in atmospheric pCO_(2).Concurrently,this uplift played a crucial role in the establishment of the East Asian monsoon and North Atlantic deep-water circulations,both of which played a part in triggering the late Cenozoic ice age.These models suggest that the teleconnections between land and sea(orogeny-terrestrial weathering-marine carbon burial)span over the whole Phanerozoic and might have played a key role in balancing the Earth surface system.Combined,the tectonic,volcanic,paleo-climatic,as well as paleoenvironmental events recorded in the Tethys oceans and adjunct continents represent valuable natural experiments and lessons for understanding the present and the future of Earth's habitability.

Spectral and biodistributional engineering of deep near-infrared chromophore

Fluorescence-guided surgery calls for development of near-infrared fluorophores.Despite the wide-spread application and a safe clinical record of Indocyanine Green(ICG),its maximal absorption wavelength at780 nm is rather short and longer-wavelength dyes are desired to exploit such benefits as low phototoxicity and deep penetration depth.Here,we report ECY,a stable deep near-infrared(NIR)fluorochromic scaffold absorbing/emitting at 836/871 nm with a fluorescence quantum yield of 16%in CH_(2)Cl_(2).ECY was further rationally engineered for biological distribution specificity.Analogous bearing different numbers of sulfonate group or a polyethylene glycol chain were synthesized.By screening this focused library upon intravenous injection to BALB/c mice,ECYS2 was identified to be a suitable candidate for bioimaging of organs involved in hepatobiliary excretion,and ECYPEG was found to be a superior candidate for vasculature imaging.They have potentials in intraoperative imaging.

Direct imaging of stress-induced magnetic behavior transitions

Stress induction plays a special role in performance control for material science.So far,it has remained challenging to systematically investigate magnetoelectric effect under stress-mediated interaction.Here we constructed a magnetoelectric device with piezoelectric stress induction,in which the stress plays a crucial intermediate role during the controllable modification of the magnetic behavior transitions under the magnetic field or current pulse driven process.The compressive stress was found to make the above process easier and reduce energy consumption via changing the magnetic domain energy state.Meanwhile,both the domain distribution and domain-wall driven process are sensitive to stress intensity.Our magnetoelectric device integrated the advantages of voltage-stress and spin-current for the control of magnetic behavior transition with the help of micro-nano processing.For the stress-induced magnetic behavior in magnetic materials was directly imaged and quantificationally investigated,the complex interactions between stress,magnetic domain motion,magnetic field,and spin current have been clarified.

Triassic integrative stratigraphy and timescale of China

The Triassic rocks are widespread in China, and both marine and terrestrial strata are well developed. The Triassic stratigraphic architecture of China is very complex in both spatial variation of the so-called "South Marine and North Continental", i.e. the southern areas of China occupied mostly by marine facies while the northern China by terrestrial facies during the Triassic Period, and temporal transition of the "Lower Marine and Upper Continental", i.e. the lower part of the Triassic System composed mainly of marine facies and the upper part of terrestrial strata especially in South China. Although the Global Stratotype Section and Point(GSSP) of the Permian-Triassic boundary is located in South China, the Triassic of China except for some marine Lower-Middle Triassic depositions shows significantly local characteristics and is hardly correlated with the global chronostratigraphic chart. Consequently, the Triassic of China contains not only the international research hotspots but also difficult points in stratigraphic study. This paper aims to present a brief review of the Triassic in China, including chronostratigraphy, biostratigraphy, magnetostratigraphy and chemostratigraphy, and summarize an integrated Triassic stratigraphic framework of China. Accordingly, a stratigraphic correlation is proposed for the lithostratigraphic sequences among the three tectono-paleogeographic stratigraphic regions. The comprehensive study indicates that ammonoids are the classic index fossils in Triassic biostratigraphy but conodonts are more advantageous in the study and definition of the Triassic chronostratigraphic boundaries. China still has the potential to optimize the GSSPs of the Induan-Olenekian boundary and Olenekian-Anisian boundary. The correlation of the Permian-Triassic boundary between marine and terrestrial facies might be achieved with the help of the Permian-Triassic "transitional bed" and its related biotic and environmental events in association with the biostratigraphic study of conchostracan, vertebrate and plant fossils. In addition, the carbon isotopes have been proved to be one of the powerful methods in marine Triassic stratigraphic study, whereas the oxygen and strontium isotopes may be additional important bridges to establish the correlation between the marine and terrestrial strata, but as yet lacking of relevant studies in terrestrial strata. Considering the most stratigraphic intervals of the Triassic and the terrestrial Triassic in China are difficult to be correlated to the global chart, the proposed Chinese(regional) Triassic chronostratigraphic chart of marine and terrestrial stages would be of importance to the study of Chinese Triassic stratigraphy and related aspects, but the stages must be conceptually in line with international standards and studied as soon as possible in order to finalize the definition.

Dual strategy of modulating growth temperature and inserting ultrathin barrier to enhance the wave function overlap in type-Ⅱ superlattices

Maximizing wave function overlap(WFO)within type-II superlattices(T2SL)is demonstrated to be important for improving their photoelectric properties,such as optical transition strength and quantum efficiency,which,however,remains a great challenge for now.Herein,the dual strategy of modulating growth temperature and inserting ultrathin AlAs barrier into the AlSb layers is presented to enhance the WFO in InAs/AlSb T2SL.The charge distributions and strain states indicate that moderate growth temperature of 470°C promotes the As-Sb exchange at AlSb-on-InAs(AOI)interfaces,which would introduce skew of energy band structure towards InAs-on-AlSb(IOA)interface.Such band structure could drive electrons and holes to the IOA interfaces simultaneously,thus resulting in the enhanced WFO.On this basis,insertion of relatively thick(0.3 nm)AlAs layers is found to squeeze more holes towards adjacent interfaces,boosting the WFO further.The InAs/AlSb superlattices with optimized WFO reveal better optical performance,where the peak intensity shows 50%improvement in the PL spectra than the original one.Moreover,a dual-miniband radiative transition mechanism appears in the InAs/AlSb superlattice with relatively thick AlAs intercalation,which helps broaden the wavelength range of the superlattice.

3D electromagnetic modelling for high-temperature superconducting dynamo flux pumps using T-A formulation

A high-temperature superconducting(HTS)dynamo flux pump can inject DC currents into closed-loop HTS magnets without contact.It enables the realisation of current-lead-free or even through-wall charging systems for high-field applications such as nuclear magnetic resonance/magnetic resonance imaging(MRI)magnets,fusion reactors and accelerators.Researchers have proposed many simulation models to understand the working principle of HTS dynamos,few of which are in 3D because of converging problems.Therefore,the influences of many key 3D parameters in the HTS dynamo are scarcely reported.The authors propose an efficient 3D modelling method of the HTS dynamo based on the T-A formulation.The rotating magnets are modelled by a ring-shaped permanent magnet with space-time-variant remanent flux density to avoid moving meshes.This,together with the T-A formulation,makes the 3D model efficient and universal.The accuracy of the model is verified by the experimental instantaneous and time-integrated dynamic voltages.Using this model,the authors present systematic case studies to thoroughly explore the influences of the key parameters of a dynamo flux pump on the dynamic voltage and losses.The proposed modelling method and results could significantly benefit the design and optimisation of HTS dynamos for high-field magnets.