Model for Quantitatively Estimating Marine Biogeographic Provinciality——A Case Study of the Permian Marine Biogeography Provincialism

The relationship between the number, position and orientation of lithosphericplates and marine biogeographic provinciality may be quantified since the spatial distribution oforganisms is primarily controlled by latitude-related temperature gradients and geographicalbarriers-two dynamic biogeographic determinants whose variation is closely related to thespatial disposition of continents and oceans. This paper modifies Schopf s (1976) model forquantitatively estimating shallow marine provinciality in recognition of latitude-related tem-perature gradients as the primary biogeographical factor. A test of the modified model againstmodern marine zoogeography reveals high consistency between them. Using this modified mod-el and the Permian palaeogeographical reconstruction maps of Scotese and McKerrow (1990),fifteen shallow benthic marine provinces are estimated to be Early and Late Permian in agerespectively. A comparison of the estimated Permian marine provinciality with previouslyrecognised empirical provincial patterns reveals a high degree of congruity, which may implythat there existed moderate to high latitudinal thermal gradients during the Permian, a levelprobably similar to that of the present world.     

佳木斯地块片麻状花岗岩的锆石离子探针U—Pb年龄

我国东北地区佳木斯地块分布有大量的花岗质岩石，这些花岗岩可分为两个大的类型，其一为基底花岗片麻岩类，岩石曾经历过50Ma左右的角闪岩相－麻粒岩相变质作用的改造，并具有与麻山群变质岩系相同或一致的片麻理构造。其二为片麻状花岗岩类，片麻理发育程度不等，岩石显示明显的岩浆结晶结构，不具有任何后期变质作用叠加的痕迹，传统认为片麻状花岗岩形成于新元古代，但本文通过高精度的锆石离子探针U－Pb测年表明，这些花岗岩主要形成于270－254Ma的晚古生代，且部分岩石中含有较老的锆石颗粒或残留，表明这些花岗岩主要来源于基底岩石的部分熔融，测定岩石的矿物组成和化学成分特点暗示，它的形成可能与佳木斯地块与周围块体或佳木斯地块内部块体间的拼合作用有关。     

Impact of Brunswick River Mouth Training Walls on Adjacent Beaches, Brunswick Heads, New South Wales, Australia

1 .IntroductionTheBrunswickbeach barrierbegantodeveloparound 6 50 0yearsagoattheendofthepostglacialmarinetransgression .Onshoreandalongshoretransportofmarinesandsoccurredfollowingthestabi lizationofsealevelresultinginbeachandduneextensionwhichoccurredonmanyNSWbeachesuntilabout30 0 0to 1 0 0 0yearsBP (Roy ,1 980 ) ,followedbyperiodsofstabilitytorecession .TherecessionalongthenorthernNSWandsouthernQLDcoastisattributedtocontinuingnorthwardlongshoresandtransportestimatedatbetween 2 0 0 0 0 0m…     

Evolution of the Mesozoic Granites in the Xiong'ershan-Waifangshan Region,Western Henan Province,China,and Its Tectonic Implications

Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong'ershan-Waifangshan region in western Henan Province: high-Ba-SrⅠ-type granite emplaced in the early stage (～160 Ma),Ⅰ-type granite in the middle stage (～130 Ma) and anorogenic A-type granite in the late stage (～115 Ma). Geochemical characteristics of the high-Ba-SrⅠ-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New 40Ar/39Ar plateau ages of the early-stage Wuzhangshan granite (156.0±1.1 Ma, amphibole) and middle-stage Heyu granite (131.8±0.7 Ma, biotite) are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A-type granite, Taishanmiao pluton, was emplaced at～115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between～160 Ma and～115 Ma. The genesis of the early- and middle-stageⅠ-type granites could be linked to delamination of subducted lithosphere of the Qiniing orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qiniing -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial 87Sr/86Sr ratios, which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratons.     

Multi-collector ICP-MS Analysis of Pb Isotope Ratios in Rocks: Data, Procedure and Caution

The authors measured Pb isotope compositions of seven USGS rock reference standards, i.e. AGV-1, AGV-2, BHVO-1, BHVO-2, BCR-2, BER-1/1 and W-2, together with NBS 981 using a micromass isoprobe multi-collector inductively-coupled plasma mass spectrometer (MC-ICP-MS) at the University of Queensland. 203Tl-205Tl isotopes were used as an internal standard to correct for mass-dependant isotopic fractionation. The results for both NBS 981 and USGS rock standards AGV-1 and BHVO-1 are comparable to or better than double- and triple-spike TIMS (thermal ionization mass spectrometry) data in precision. The data for BHVO-2 and, to a lesser extent, AGV-2 and BCR-2 are reproducibly higher for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb than double-spike TIMS data in the literature. The authors also obtained the Pb isotope data for BIR-1/1 and W-2, which may be used as reference values in future studies. It is found that linear correction for Pb isotopic fractionation is adequate with the results identical to those corre     

Desorption-diffusion model and lost gas quantity estimation of coalbed methane from coal core under drilling fluid medium

The differences of coalbed methane(CBM) desorption-diffusion from coal drilling-core under various drilling fluid medium are not considered in the present calculating methods of lost CBM quantity,which leads possibly to the inaccuracy of CBM quantity in coal seam.Here we took the desorption of CBM from coal core under drilling fluid medium as a pressure-swing process,and based on the Langmuir equation and Fick-first law,established the desorption-diffusion model and numerical modeling method of lost gas(inc...     

陆内克拉通盆地层序地层构型及其控制因素

通过总结我国鄂尔多斯盆地和澳大利亚Surat basin这两个典型的陆内克拉通盆地的层序充填序列,认为该类盆地具有典型的层序地层充填模式:(1)典型的正粒序岩性组合特征;(2)基准面旋回为上升半旋回为主的不对称旋回,具有长期持续水进、短期水退旋回特征;(3)层序主要以LST为主,发育相互切割叠置的复合砂体,为最有利储层;TST和HST相对不发育,发育孤立状的单砂体,为中-差储层.陆内克拉通盆地层序地层及其控制的砂体具有溯源退积的时空展布模式,该模式主要受到盆地边缘构造、沉积物供给、湖平面变化、古地形、盆地充填和气候等因素的单独或综合控制.     

Mookaite石——西澳大利亚的装饰石

Mookaite石是一种吸引人的多色装饰石,产于西澳大利亚Kennedy山脉西缘Gascoyne河以北的少数地方。从岩石学上,Mookaite石由Windalia放射虫岩层的硅化放射虫岩构成,该岩层为Carnarvon大盆地沉积序列的一部分。硅化作用形成瓷状岩后,Fe染色导致其具有引人瞩目的黄色、红色、紫色和棕色图形。瓷状岩细粒,坚硬,无定向性,抛光性极好,在世界范围内广受欢迎。