There is no such thing as the ‘Ediacara Biota'

The term‘Ediacara Biota’(or many variants thereof)is commonly used to refer to certain megascopic fossils of Precambrian and early Palaeozoic age e but what does the term actually mean?What differentiates a non-Ediacaran‘Ediacaran’and an Ediacaran‘Ediacaran’from an Ediacaran non-‘Ediacaran’?Historically,the term has been used in either a geographic,stratigraphic,taphonomic,or biologic sense.More recent research and new discoveries,however,mean that the term cannot actually be defned on any of these bases,or any combination thereof.Indeed,the term is now used and understood in a manner which is internally inconsistent,and unintentionally implies that these fossils are somehow distinct from other fossil assemblages,which is simply not the case.Continued use of the term is a historical relic,which has led in part to incorrect assumptions that the‘Ediacara Biota’can be treated as a single coherent group,has obscured our understanding of the biological change over the PrecambrianeCambrian boundary,and has confused research on the early evolution of the Metazoa.In the future,the term‘Ediacaran’should be restricted to purely stratigraphic usage,regardless of affnity,geography,or taphonomy;suffcient terminology also exists where reference to specimens on a geographic,taphonomic,or biologic basis is required.It is therefore time to abandon the term‘Ediacara Biota’and to instead treat equally all of the fossils of the Ediacaran System.     

Modes of Occurrence and Geological Origin of Beryllium in Coals from the Pu＇an Coalfield, Guizhou, Southwest China

The concentration, modes of occurrence and geological origin of beryllium in five workable coal beds from the Pu＇an Coalfield of Guizhou were studied using the inductively coupled-plasma mass spectrometry （ICP-MS）, floating and sinking experiments （FSE） and sequential chemical extraction procedures （SCEP）. The results show that the average concentration of beryllium in coals from the Pu＇an Coalfield is 1.54 μg/g, much lower than that in most Chinese and worldwide coals. Beryllium in the Pu＇an coals was not significantly enriched. However, it should be noted that the No. 8 coal bed from the study area has a high concentration of beryllium, 6.89 μg/g, three times higher than the background value of beryllium in coal. Beryllium in coal mainly occurs as organic association and has predominantly originated from coal-forming plants when its concentration is relatively low. The concentration of beryllium occurring as organic association is close to that distributed in inorganic matter when beryllium concentration of coal is similar to its background value, and in addition to coal-forming plants, beryllium is mainly derived from detrital materials of terrigenous origin. When beryllium is anomalously enriched in coal, it mainly occurs as organic association and is derived from volcanic tonsteins leached for a long geological time and then adsorbed by organic matter in peat mire.     

Sm／Nd Evolution of Upper Mantle and Continental Crust：Constraints on Gowth Rates of the Continental Crust

A new approach to the investigation of the Sm/Nd evolution of the upper mantle directly from the data on lherzolite xenoliths is described in this paper.It is demonstrated that the model age TCHUR of an unmetasomatic iherzolite zenolith ca represent the mean depletion age of its mantle source, thus presenting a correlation trend between f^Sm/Nd and the mean depletion age of the upper mantle from the data on xenoliths.This correlation trend can also be derived from the data on river suspended loads as well as from granitoids.Based on the correlation trend mentioned above and mean depletion ages of the upper mantle at various geological times, an evolution curve for the mean f^Sm/Nd value of the upper mantle through geological time has been established.It is suggested that the upwilling of lower mantle material into the upper mantle and the recycling of continental crust material during the Archean were more active ,thus maintaining fairly constantf^Sm/Nd and εNd values during this time period. Similarly ,an evolution curve for the mean f^Sm/Nd value of the continental crust through geological time has also been established from the data of continental crust material.In the light of both evolution curves for the upper mantle and continental crust ,a growth curve for the continental crust has been worked out ,suggesting that :(1)about 30%(in volume )of the present crust was present as the continental crust at 3.8 Ga ago ;(2)the growth rate was much lower during the Archean ;and (3)the Proterozoic is another major period of time during which the continental crust wsa built up .     

http://www.sciencedirect.com/science/article/pii/S1674987112001533

The collision of a divergent ocean ridge may evolve into two end cases:in the continuity of ocean-floor subduction.or in the detachment of the subducted plate.The northern Patagonia active plate margin has the unique situation that in Cenozoic time it has been subjected to two divergent ridge collisions,each one representing one of the end members.The Neogene Antarctica-Nazca divergent ridge collision evolved as a continuous ocean-floor subduction system,promoting a magmatic hiatus at the arc axis,the obduction of part of the ridge ocean-floor in the fore-arc.and basaltic volcanism in the back-arc.In contrast,the Paleogene Farallon-Aluk divergent ridge collision evolved into a transform margin,with the detachment and sinking of the Aluk plate and the development of a large slab window.As in the previous case,this collision promoted a magmatic hiatus at the arc axis,but the tectono-magmatic scenario changed to postorogenic synextensional volcanism that spread to the former fore-arc（basalt,andesite,rhyolite） and former back-arc（bimodal ignimbrite flare-up,basalt）.Geochemistry of this slab window synextensional volcanism shows more MORB-like basalts towards the former fore-arc,and MORB-OIB-like basalts towards the former back-arc.Instead,an isolated undeformable crustal block in the former back-arc,with an "epeirogenic" response to the slab window and extensional regime,was covered by OIB-type basalts after uplift.Major elements show that slab window basalts reach TiCh values up to 3 wt%,as compared with the top value of 1.5 wt%of arc magmas.Besides,the MgO with respect to（FeO^t + Al₂O₃） ratio helps to distinguish slab window magma changes from the former fore-arc to the former back-arc and also with respect to the "epeirogenic" block.Higher contents of HFS elements such as Nb and Ta also help to distinguish this slab window from arc magmas and also,to distinguish slab window magma changes from the former fore-arc to the former back-arc and "epeirogenic" block settings.The isotope compositions of slab window magmatism show a disparate coeval array from MORB to crustal sources,interpreted as a consequence of the lack of protracted storage and homogenization due to the extensional setting.     

Tree-Ring Carbon Isotopic Constraints on Carbon-Water Exchanges between Atmosphere and Biosphere in Drought Regions in Northwestern China

The comparison between the carbon isotope and the index of ring width of a pine disc from the Tuomuer Peak region in Xinjiang shows that the effects of climate changes on the tree-ring growth and carbon iso-topic fractionation varies with time. The reason is probably relative to the characters of climate changes and adaptability of the tree-ring growth to climate changes. The relationships between the atmospheric CO2 level and the revised δ13Cair by the tree-ring carbon isotope indicate that the carbon cycle is not in a steady state, but under a stage-change condition in this area. It also can be concluded that the ratio of CO2 from the terrestrial eco-system has increased, and the flux of CO2 exchange between the atmosphere and the biosphere was gradually increasing over the past century. In addition, the results also confirm the validity and superiority of the carbon isotope to the research of the water-use efficiency.     

SEDIMENTARY RESPONSES TO THRUSTING AND STRIKE-SLIPPING OF LONGMEN SHAN ALONG THE EASTERN MARGIN OF TIBETAN PLATEAU AND IMPLICATIONS FOR ACCRETION OF CIMMERIAN CONTINENTS AND INDIA/EURASIA COLLISION

1. Introduction A central goal of stratigraphic studies of foreland basins is to discern which of the possible controls is responsible for vertical trends. In many cases, the primary interest has been to determine the time of deformation in the mountain belt from strata in the foreland basin (Jordan et al., 1988). Traditionally, an active tectonic phase was presumed to cause high relief, and then an immediate flux of coarse sediment into the basin, which produced conglomerates (Longwell, 193…     

论地球演化与银河系的关系——宇宙地球观刍议

Various changes, or geological events, and. their periodicity involved in the evolution of the earth can hardly be explained satisfactorily and completely only in terms of the earth itself. More recently, ever-increasing attention has been paid to the influence of the solar system and the galactic system, even that of the vast cosmic space. This paper intends to discuss the relationship between the earth‘s evolution and the galactic system, based on the revolution of the solar system and other space factors. It is well-known that one period in which the solar system moves around the gtlactic centre is defined as one cosmic year (ca. 220---250m.y.). A good many facts have shown that the periodicity of various changes involved in the evolution of the earth, such as climatic fluctuation, crustal movement, magmatic activity, biological evolution, eustatic movement, elemental synthesis, the reversal of polarity of the earth‘s magnetic field, the variation of the speed of earth‘s rotation, etc. is generally consistent with the concept of cosmic year, which reflects the internal connection between the evolution of the earth and the galactic system. The author has proposed that the revolution of the solar system orbiting around the galactic centre with an ellipticy of 0.07--0.1, the speed of earth‘s rotation, and the annual average distance between the sun and the earth, as well as some space physical fields, such as magnetic field,radiation field, etc. are all characterized by cosmic year periodic variatioons. Under the influence of these cosmic factors, various changes involved in the evolution of the earth are also characterized by cosmic year periodicity. The exploration of the regularities governing the earth‘s evolution and its origin from the concept of cosmic year periodicity, coupled with astronomical, cosmological and geological data, will give a great impetus to the rapid development of earth sciences. Research in this respect is of great significance both in theory and practice with respect to astronomy, geology and philosophy.     

Nonlinear Dynamic Study on Geomagnetic Polarity Reversal and Cretaceous Normal Superchron

It is generally acknowledged that geomagnetic polarity has reversed many times in geological history and an abnormal geologic phenomenon is the Cretaceous normal superchron. However, the causes have been unknown up to now. The nonlinear theory has been applied to analyze the phenomenon in geomagnetic polarity reversal and the Cretaceous normal superchron. The Cretaceous normal superchron implies that interaction of the Earth’s core-mantle and liquid movement in the outer core may be the lowest energy state and the system of Earth magnetic field maintains a sort of temporal or spatial order structure by exchanging substance and energy in the outside continuously. During 121-83 Ma, there was no impact of a celestial body that would result in a geomagnetic polarity reversal, which may be a cause for occurrence of the Cretaceous normal superchron.The randomness of geomagnetic polarity reversal has the self-reversion characteristic of chaos and the chaos theory gives a simple and clear explanation for the dynamic cause of the geomagnetic polarity reversal.     

http://www.sciencedirect.com/science/article/pii/S1674987111000466

The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil,gas and coal in China.The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies,but it has not been well understood in terms of the hydrodynamics of basin fluid flow.We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing,reducing fluid and a downward flowing,oxidizing fluid.This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow,and topographic relief,which drove the downward flow.In this study,we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure,in addition to sediment compaction and heating.Our results indicate that when hydrocarbon generation is taken into account,fluid overpressure during the Cretaceous was more than doubled in comparison with the simulation when hydrocarbon generation was not considered.Furthermore,fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case.These results suggest that hydrocarbon generation may have played an important role in uranium mineralization,not only in providing reducing agents required for the mineralization,but also in contributing to the driving force to maintain the upward flow.     

A new schedule for copper chemical speciation analysis in soil and water sediment

The speciation of heavy metals is very important to evaluate their environmental impact. This issue has become an interested topic many decades ago and many significative studies were carried out such as direct detecting, calculation with mathematical model represented in recent years as well as Tessier＇s work in 1979, BCR＇s work in 1993, etc. In all of them, the methods recommended by Tessier and BCR are most often used in practical study today. But it should be seen that experimental schedule and agents define these methods including BCR＇s method, which improved on Tessier＇s method, only. In many cases, there always are deviations between analytical results and real content of the speciation. Otherwise, steps of the extraction experiment are always strict and excessive in the experimental process. The method, which is fitting to extract the speciation of bioavailability and easy to assess the effect of metals in the environment, is very anticipant. In this paper, the sequential three steps schedule of speciation analysis of copper in soil and water sediment is discussed as an example based on the comparative results of experimental analysis with the schedules of BCR＇s （mended by Rauret et al. in 1999） and TDPA （diethylenetriamine pentacetic acid） extraction, respectively. The results from sequential three steps method and other methods recommended by prevenient work suggest that the analytical schedule of sequential three steps of separating speciation （the speciation of easy effect to life-form, the speciation available to life-form, and the speciation of no effect to life-form） is valuable for copper speciation analysis in soil and sediment. Because of easy process and saving time to evaluate its availability for life form,     

Dynamic Features of Angular Unconformity Formation——Extensional and Compressional Angular Unconformities

Angular unconformity is one of the most direct and strongest evidences for approving the tectonic movements of the earth's crust. Its dynamic genesis process has been understood to be mainly related to the compressional setting for a long time. Especially, in a detailed structural analysis for a specific region, when an angular unconformity is discovered people would regard it as the result of orogenic movements of a certain period or a certain episode and neglect the extensional facts. Based on a dialectical point of view of extension-compression, this paper has proved that angular unconformities can be formed not only in compressional settings, but also in extensional ones. Further more, their geological features are compared and he possible genetic mechanisms for angular unconformity under different dynamic settings are studied.     

某地含黑稀金矿花岗岩脉的初步研究

An investigation has been conducted of the geological and geochemical characteristics of euxenitebearing granitic veins found for the first time in China. It is shown that these veins are late intrusives in an Yah Shah granitic complex at a geosyclinal folded zone and composed mainly of medium grained biotite granite in which the local enrichment of euxenite during the late period of magmatic activity is obvious. The mineral has been found to be metamiet and chemically represent a transitional member between euxenite and polyclase. This study has provided a typical example that gralitic melts with a lower initial content of rare elements would contribute significantly to the local enrichment of rare element minerals under special external conditions.     

The Factors for Transformation between the Fractions of Speciation of Trace Metals in Lake Sediments

<正>Objective Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensable parameter in the assessment and treatment of the environmental pollution of trace metals,many studies have suggested that the bioavailability of trace metals may change according to the conditions of the environment,     

Acclimatization and screening of a chloramphenicol-degrading strain

Chloramphenicol （CAP） is an antibiotic commonly used in aquaculture as a prophylactic or disinfectant to prevent diseases, or as a chemotherapeutic agent to control diseases. This antibiotic is either spread directly in the aquatic environment or administered through medicated feeds. It may be directly exposed to or enter the environment by leaching from uneaten feeds or from the aquatic animals＇ excrements. The antibiotic also directly enters the environment through pharmaceutical wastewater. Toxicity of CAP to human bone marrow has been linked to fatal aplastic anemia. Antimicrobial residues enter the environment, which may also establish a selective pressure in favour of antimicrobial-resistant bacteria. The residues of antibiotics may pose potential risk to public health or increase the occurrence of antibiotic-resistant bacteria in the aquatic environment. Due to these perceived risk, treatment of CAP in farm animals intended for human consumption has been restricted. However, residue of CAP in the environment is still a concern. There have been some reports on the residual effects of CAP on aquaculture and on microbial resistance to CAP in certain environments. The biotransformation of CAP in aquaculture pond sediments has been reported, which indicated that salinity is one of the many environmental factors that affect the degradation of CAP. However, acclimatization and screening of dominant bacteria for biodegrading CAP have been rarely studied. This paper studied the microbial degradation of CAP. In order to screen the dominant bacteria for degrading, the source of bacteria was sampled from the aquaculture pond sediments of Baiyun Borough, Guangzhou, China. 60 mg/L CAP was used as a sole carbon source to screen CAP-degrading bacteria and the dominant bacteria were acclimated after 2 months.     

特提斯喜马拉雅多重基性岩浆事件：追溯新特提斯洋的生存时限

Processes accompanied the breakup of continents, spreading of ocean floor and continent-ocean transi-tion could trigger large scale melting of the mantle beneath the continent as well as the ocean, and pro-duce mafic magmas with distinct geochemical charac-teristics. Such rocks provide us an important record for unraveling the nature and the time of deep tectonic and magmatic processes during the tectonic evolution of large-scale orogenic belts, such as the Himalayan orogenic belt. As an integrated part of the Himalaya, the Tethyan Himalaya consists of well-developed early Paleozoic to Cenozoic sediments and is noted for de-velopment of spectacular semi-continuous, thousand kilometers long gneiss (or granitic) domes. It has pre-served critical records to address the nature of defor-mation, magmatism, and metamorphism associated with the opening, spreading, and demise of the Neo-Tethyan Ocean and the final continental collision between the Indian and the Eurasian Plate at the early Cenozoic time. In addition, it also could be a type-example to address a number of first-order issues with regard to the tectonic dynamics of passive conti-nental margin during the Wilson-cycle.     

Saharan dust clouds and paediatric asthma in the Caribbean Island of Trinidad

Background： African dust clouds reach the islands of Trinidad and Tobago from January to October of each year. There has been evidence of increased amounts of Saharan dust being transported across the Atlantic to the Americas from the mid 1960s. Since then, there has also been independent evidence of increased numbers of patients with asthma attending Accident and Emergency （A and E） departments in the region for treatment of asthma exacerbations. We therefore hypothesize that Saharan dust clouds could be an important trigger of acute asthma in children in Trinidad. Methodology： A retrospective ecological study of paediatric asthma admissions to the Eric Williams Medical Sciences Complex, the main tertiary paediatric centre in Trinidad. Data were collected for the period 2001-2002. Data on climate parameters and Saharan dust cover were also obtained from the island＇s sole meteorological （MET） centre. The MET office uses a standard scale of visibility to measure Saharan dust levels. A Poisson Regression model was used to model the log of the mean of daily asthma visits as a function of the variables; month, visibility, atmospheric pressure, humidity and temperature. Results： There was an association between increased paediatric asthma admissions and increased Sahara dust cover noted. The best fitting model estimated that in one month such as June a deterioration of visibility due to increased Sahara dust cover from no dust （visibility=16 km） to very dusty （visibility=7 km） would increase a daily admission of 7.8 to 9.25 when climate variables such as barometric pressure and humidity were kept constant.     

Impact of forest fires on regional air quality in Southeast Asia

Biomass burning, the burning of living and dead vegetation for land-clearing and land-use change, has been in practice in many tropical countries such as Brazil, Indonesia, Nigeria, and Mexico. Intense forest fires can also ignite subsurface organic soil components （e.g. peat）, which can continue to smolder long after the original surface fires are put out. Combustion of vegetation and peat has only recently been recognized as a major source of atmospheric pollution. The immediate effect of burning is the production and release of gases and particles into the atmosphere, in quantities that in some cases can be significant not only locally and regionally but also on a global scale. Vegetation fire emissions account for roughly half of the atmospheric constituents of hydrocarbon, carbon monoxide, nitrogen oxides, and precursors of tropospheric ozone and may be the second largest source of anthropogenic aerosols after the production of sulfates from SO2. As a result, there has been considerable interest in studying the contribution of forest fires to the production of air pollutants. In recent years, Southeast Asian countries have been affected repeatedly by episodes of smoke haze from forest fires in Indonesia. During 1997-1998, the region was again shrouded in a haze worsened by prolonged drought linked to the E1 Nino weather phenomenon. Satellite pictures confirmed that air pollutants, originating from fires covering an estimated 800000 hectares of southern Kalimantan, Sumatra, and Java, have been transported by southwesterly monsoon winds across neighbouring Malaysia and Singapore to as far as Thailand and the Philippines. The impact of these extensive fires on the health of the residents and ecology in the affected areas was substantial, costly, and possibly long lasting. Most of the research on the environmental aspects of biomass burning has been directed towards the tropics in Africa and America, specifically to the tropical rain forests of Brazil and to the savannas of Africa and South America.     

重砂元素分析与趋势面分析

Summing up the abundant experience obtained by the author through many years of his work in mineral separation, an inversion formula has been proposed for calculating the element content in a sample and thus the proportion of minerals containing those elements in the sample. In terms of this inversion formula, the proportion of associated minerals containing the analyzed elements in the sample can be worked out.Long-term practice has proved that if the elcments analyzed quantitatively excees the defined limits, it will be shown that there exist independent minerals in the analyzed sample, and in the opposite case, it may be indicated that there is no presence of such minerals. The element content mainly depends on the type, proportion and grain-size of host minerals. The approach highly sophisticates the traditional method, by which one can not only know the association relations of minerals, but also get sights into the relative proporthin of associated minerals, thus making a very big step in the study of mineral associations from qualitative to quantitative level.     

地质体中氨基酸的研究

A clearer idea about the distribution of total amino acid content has been obtained through its quantitative determination in various geological bodies. Because amino acid content is strongly correlated with organic carbon content in the same sedimentary rock, therefore, an attempt has been made to use their ratio to distinguish the primary types of biological debris in sediment. In addition, the quantitative determination of individual amino acids has been also carried out on several specimens from ancient sedimentary rocks, and the results show that their amino acid pattern is almost similar to that of the recent sedimentary muds.     

The Paleoproterozoic and Neoproterozoic Carbon Cycle Promoted the Evolution of a Habitable Earth

The carbon cycle is an important process that regulates Earth’s evolution. We compare two typical periods, in the Paleoproterozoic and Neoproterozoic, in which many geological events occurred. It remains an open question when modern plate tectonics started on Earth and how it has influenced the carbon cycle through time. In the Paleoproterozoic, intense weathering in a highly CO₂ and CH₄ rich atmosphere caused more nutritional elements to be carried into the ocean.Terrestri...