Trace fossils or biogenic sedimentary structures are autochthonous indicators of environmental conditions,and hence trace fossil communities have been the subject of palaeoenvironmental and palaeogeographic investigation for
several decadesFour aspects are discussed:(1)distinction between terrestrial and marine trace fossil communities;(2)
trace fossil communities of the transitional zone and recognition of shoreline;(3)the applications of some ichnofacies in palaeoenvironmental and palaeogeographic studies and recent advances in investigation of Skolithos,Cruziana,Zoophycos and Nereites ichnofacies;and(4)trace fossil communities for interpretation of some geological events,including interpretation of some sedimentary events and recognition of anoxic environments

Late Permian submarine fan turbidites are well developed in the Laibin\|Heshan area and are  particularly well exposed in the Matan and Penglaitan sections along the Hongshui River Varieties of sedimentary structures formed by sedimentary gravity flow have been found in the field sections, such as graded beddings, flute casts, load casts, dish structures, and slump\|folded layers The lithofacies of Late Permian Heshan Formation and Dalong Formation in the Penglaitan section and Late Permian Dalong Formation in the Matan section have been studied in detail. It is proposed that these formations were formed in a submarine fan Lithofacies such as massive sandstones with dish structures (B1), massive sandstones (B2), proximal turbidites (C), distal turbidites (D), irregularly interbedded sandstones and mudstones (E), slump\|folded layers (F), and shales and siliceous rocks with planktons (G) have been recognized in the study area The outer fan, mid fan lobe, mid fan channel, slope and incised valley facies associations have been summarised  The palaeogeographic implications of these turbidites are also discussed. It is here considered that these turbidites were formed in deep marine environments between the Central Guangxi carbonate platform and the Yunkai Oldland, with an average water depth between 300 m and 1000 m Provenance in the Heshan area was volcanic,while the sediments in the Laibin area were mainly terrestrial and were derived from the Yunkai Oldland to the east

During the Early Palaeozoic, the South Qinling belonged to the passive continental margin of the Yangtze Plate.It changed to ancient land due to vertical movement in the end of the Silurian. Because its southern margin located in the structure weak zone caused by mantle bugle for a long time , during the Devonian extension first began to form here and  a restricted oceanic basin was formed gradually while South Qinling separated from the Yangtze Plate and changed into an independent plate.The environmental framework that faultsubsided basins alternated with blockfaulted uplifts was formed by extension. They are Ankang Uplift→XunyangZhenan Basin→Xiaomoling Uplift→Liuling Basin  from south to north, respectively. These basins were generally filled with upward fining and deepening sedimentary sequence that comprises nonmarine to marine,shallow marine to deep marine depositional systems. At the same time,this plate still subducted beneath the  North China Plate. The forearc deposition system at the southern margin of North Qinling indirectly recorded this evolution of subduction. The much different palaeogeographic framework from the Early Palaeozoic indicates that Qinling orogenic belt has entered a new evolutionary stage.

There are Holocene beachrocks exposed on the sandy beach of the midintertidal zone in thirteen coves between rock headlands along the coast in Zhejiang Province Except for Lianyungang beachrock,Zhejiang beachrocks are the northernmost ones found in China, located in the middle subtropicThe age from data of 14C is from 2 705 a±160 a BP to 6 485 a±210 a BP. Its basic features and palaeogeographic significance were discussed Results of the study indicate that the grains(shells and their fragments of in
tertidalneritic bivalves,gastropods,foraminiferas and ostracods, and clasts of granite,etc.) which are produced by marine processes,grainsupported texture and aragonite as the cement are the most important features of the beachrocksFavourable geomorphologic landscape, such as in a cove with sandy beach,sufficient supplies of grains including terrigenous detritus,quartz,feldspar,and a large amount of bioclasts,moderate grain size and hydrodynamic conditions ,stable sea level and high temperature influence the formation of the beachrocksDuring formation of the beachrocks,the coastline of the middlenorthern part of Zhejiang Province was basically stable,and Donghai Sea longshore current was not the low temperature current like the presentIts temperature was about 5～６℃(at least 2℃)higher than the present,whereas it was the low salinity current like the present. Zhejiang Province belonged to the tropical climate zone,or climatic zonation was not distinct at that time

Based on the study of stratigraphy and quantitative sedimentology of  fundamental stratrigraphic sections, according to the “single factor analysis and comprehensive mapping method”, various single factor maps and quantitative lithofacies palaeogeography maps of the Yanguan age and Datang age of  the Early Carboniferous, and Weining age and Maping age of the Late Carboniferous in South China, were compiled. These palaeogeography maps possess three characteristics, iequantification, multirank and multitype Quantification means that the determination of each palaeogeographical unit is based on quantitative single factor dataThis makes palaeogeography develop to the quantitative stage Multirank means that palaeogeographic units are classified into three ranks or more than three ranks For instance, lands and seas are the first rank, and in seas, the platforms, basins and slopes are defined and belong to the second rank. In platforms, the banks, tidal flats and reefs are further drawn out and belong to the third rank. In second rank basins, there are third rank platforms which include fourth rank banks and reefs Multitype means that each palaeogeographic unit, especially the 2nd rank or 3rd rank units, can be further divided into different types on the basis of their rock types For instance, platforms can be classified into carbonate platforms, clastic platforms, etc; basins can be classified into carbonate basins, clastic basins, siliceous basins, turbidite basins, etc.; and banks can be classified into sparry grain banks, limemud grain banks, mixed grain banks, etc  The features of the lithofacies palaeogeography of each age of the Carboniferous can be summerized as following. There were lands and seas In seas there were platforms, basins and slopes In platforms there were banks and reefs In platforms there were basins In basins there were platforms Between platforms and basins there were slopes There were a variety of platforms, basins and banks The evolution of the lithofacies palaeogeography of the Carboniferous in South China was characterized with succession, development and stage

Stratiform tuffaceous siliceous rocks are widely exposed in the Nomhon－Xiangride area of the middle part of East Kunlun, mostly occur within volcanic lava and above itThe siliceous rocks are compact,well bedded, and are of unique geochemical featuresThey contain little organic matterTheir SiO^₂ content is relatively low, mostly ranging from 77% to 87%, while Al₂O₃, Na₂O and K₂O contents are relatively highMoreover, Na₂O content is higher than that of K₂O. w(MnO)/w(TiO₂) is much higher than 0.5, and the average of N(Al)/N(Al+Fe+Mn) ranges from 0.6 to 0.82The trace element characteristics of the siliceous rocks are obviously different from those of the siliceous rocks formed in stable sedimentary areas of the  platform typeThe abundance of the trace elements is positively proportional to that of the co existing volcanic lava evidently, with obviously high contents of  Rb, Zr, Hf, Ga, Th, Au and low contents of organismrelated and hydrothermalwaterrelated elements, such as Ba, V, Cr, Cu, Rb, U, etc The average content of REE is 833 μg/g, and LREE/∑REE value generally ranges from 0.91 to 0.98, showing relative enrichment of LREE ChondriteREE normalized patterns demonstrate“V”shape with clear Eu anomaly and very scarce Ce anomaly δ³⁰Si falls into the range from 0‰ to －0.4‰ Initial ⁸⁷Sr / ⁸⁶Sr value is 0.714 1on the average, close to that of tuffiteA series of correlation charts also indicate that the siliceous rocks have the same provenace with the coexisting volcanic lavaVarious diagrams suggest that they are formed in volcanic island arc belts or active continental margins

The Lunnan area is one of the important oil and gas producing areas in the Tarim BasinStudy of reservoir characteristics of Lower Ordovician carbonate rocks is important to  oil and gas exploration The features of karst,development of fractures,sedimentary facies and filling materials in caves were describedExistence of permeable and soluble carbonate rocks, humid climate and abundant precipitation are considered to be necessary conditions for forming karst Development of structural fractures is favorable for karst developmentAccording to the property of fractures and filling degree,the fractures are divided into five types, such as calcite full\|filled extension fractures,calcite semi\|filled extension fractures,clay filled shearing compressive fractures,non\|filled micro\|fractures and stylolites,among which calcite seim\|filled extension fractures and stylolites play an important role in development of karst reservoirs.Development of karst in this area shows obvious vertical zonation,i.e. the vertical vadose zone,the horizontal phreatic zone and the transitional zone.At the bottom of vertical vadose zone and the top of the horizontal phreatic zone,the properties of reservoir are best. The two karst developing periods for the Middle and Upper Ordovician in the Lunnan area are consistent with two transgressions of the Carboniferous.The sedimentary features of filling materials in caves were also described and  the evolutional model of karst was established

A preliminary comparison between the climatic evolution of the arid regions in North Africa andNorth China showed that the variations in the continental aridity on time scales of 104 years wereapproximately synchronous over the last 140 ka BP. Whether this relationship can be established for the Holocene drought events at centuryscale reported from tropical and equatorial Africa is still poorly known. Based on 569 reliable radiocarbon dates from surface fresh water indicators from the Sahara and 158 dates on palaeosol and lake sediments from the arid regions in North China, we demonstrate here that the Holocene environments in both regions have been affected by several approximately in phase arid events, inlaid in the slow trends attributable to the orbital forcing. The variations of the southern margins of the deserts, probably associated with the oscillations of the meteorological equator (or ITCZ) in Africa and with the northern monsoon front in China, are documented by the latitudinal distribution of these indicators through time. The most startling aspects are the severe interval at 4 000 years BP and a prolonged drier interval around 6 000 years BP. The last is given as the Holocene Optimum. However, this episode is in agreement with an important number of pollen, icecore, lacustrine and pacific eolian dust records, and also with the lower atmospheric methane concentration recorded in the GRIP icecore. The existence of this arid interval at low latitudes cannot be explained by higher evapotranspiration in the mid－Holocene, but is attributable to the weakening of the summer monsoon circulation.