Loggerhead turtle movements reconstructed from 18O and 13C profiles from commensal barnacle shells     

John S. Killingley  Molly Lutcavage 《Estuarine, Coastal and Shelf Science》1983,16(3):345-349

Commensal barnacles, Chelonibia testudinaria, from logger-head turtles have ¹⁸O and ¹³C variations in their calcitic shells that record the environments in which the turtles live. Isotopic profiles from the barnacle shells can thus be interpreted to reconstruct movements of the host turtle between open ocean and brackish-water regimes.  相似文献   

Influence of tidal inundation on internal oxygen supply of Spartina alterniflora and Spartina patens     

Mark L. Gleason  Joseph C. Zieman 《Estuarine, Coastal and Shelf Science》1981,13(1):47-57

  相似文献   

Ferric Iron in CaTiO3 Perovskite as an Oxygen Barometer for Kimberlitic Magmas I: Experimental Calibration     

Bellis  Anthony; Canil  Dante 《Journal of Petrology》2007,48(2):219-230

A method to estimate the oxygen fugacity (fO₂) during the crystallizationof kimberlites is developed using the Fe content of CaTiO₃ perovskite(Pv), a common groundmass phase in these rocks. With increasingfO₂, more Fe exists in the kimberlitic liquid as Fe³⁺, and thuspartitions into Pv. Experiments to study the partitioning ofFe between Pv and kimberlite liquid were conducted at 100 kPaon simple and complex anhydrous kimberlite bulk compositionsfrom 1130 to 1300°C over a range of fO₂ from NNO –5 to NNO + 4 (where NNO is the nickel–nickel oxide buffer),and at Nb and rare earth element (REE) contents in the startingmaterials of 0–5 wt % and 1500 ppm, respectively. Thepartitioning of Fe between Pv and kimberlite liquid is influencedmostly by fO₂, although the presence of Nb increases the partitionof Fe³⁺ into perovskite at a given T and fO₂. Multiple linearregression (MLR) of all the experimental data produces a relationshipthat describes the variation of Fe and Nb in Pv with fO₂ relativeto the NNO buffer:

(uncertaintiesat 2, and Nb and Fe as cations per three oxygens). Over therange of conditions of our experiments, this relationship showsno temperature (T) dependence, is not affected by the bulk Fecontent of the kimberlite starting material and reproduces experimentaldata to within 1 log fO₂ unit. KEY WORDS: kimberlites; oxygen fugacity; perovskite; ferric iron; magma  相似文献   

铁氧化物矿物对苯酚和溶解性有机质表面吸附的初步研究   总被引：2，自引：0，他引：2  

吴宏海  林怡英  吴嘉怡  曾丽璇  曾丁才  杜娟 《地学前缘》2008,15(6):133

文中以铁氧化物矿物对苯酚和溶解性有机质(DOM)的吸附研究为例开展生态矿物学研究。铁氧化物矿物的吸附作用存在多种机制,这些吸附机制发生作用的条件主要取决于溶液化学性质和吸附质的理化性质。批处理实验研究表明,苯酚吸附在酸性微酸性条件下不强,吸附等温线符合Langmuir方程,属于表面分子吸附模型;DOM的吸附强并发生吸附分异,配体交换、憎水键和范氏力等多种模式并存,在酸性中性条件下对DOM在针铁矿上的吸附起着重要贡献。本文实验条件下DOM吸附等温线近于线性,不能采用Langmuir方程拟合,可能原因是DOM浓度较低。矿物表面荷电性对吸附影响显著,例如,当矿物表面净电荷为零(pH=pHpzc)时,矿物表面水化膜减薄甚至消失,苯酚分子、憎水DOM分子或片断都会倾向于在矿物表面上吸附。由于苯酚吸附机制单一,其受到的影响很明显,所以苯酚在pH值7～8范围内出现吸附最大值;由于配体交换作用主要发生在酸性微酸性条件下,所以在本文pH值约7.5的实验条件下,尽管配体交换仍在发生作用,但它不是主要吸附机制,针铁矿对DOM吸附的主要贡献应是憎水键和范氏力作用,此外,DOM吸附等温方程近于线性还可能与此有关。显然,铁矿物表面作用在对有机质含量低而铁矿物含量高的红壤中污染物和DOM的固定与归宿控制中扮演着重要的角色。  相似文献   

Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing   总被引：3，自引：0，他引：3  

TIAN Jun  WANG Pinxian & CHENG Xinrong Laboratory of Marine Geology  Tongji University  Shanghai  China 《中国科学D辑(英文版)》2004,(10)

1 Astronomical theory One of the greatest achievements of the EarthSciences in the 20th century is the establishment of theMilankovitch theory or the astronomical theory[1]. AsImbrie pointed out[2], the astronomical theory can bedescribed as a simple system model. The input to thesystem can be defined as changes in the geometry ofthe Earth’s orbit or the seasonal and latitudinal distri-bution of incoming solar radiation, whereas the outputto the system can be defined as one or more calc…  相似文献   

川东南地区灯影组葡萄石地球化学特征及成因分析   总被引：3，自引：2，他引：1  

施泽进  梁平  王勇  胡修权  田亚铭  王长城 《岩石学报》2011,27(8):2263-2271

长期以来,人们对灯影组葡萄石的成因存在较大的争议。本文对灯影组葡萄石及基岩的地球化学特征进行了详细的对比分析,讨论了灯影组葡萄石的形成环境。灯影组葡萄石与基岩相比,具有较明显的Ce负异常和相对低的稀土总含量,说明了葡萄石并非是和基岩同时沉积而成;葡萄石中Na、K元素含量低而Mn、 Fe含量较高,具有很低的Sr/Ba比值,同时具有碳、氧同位素明显偏负和⁸⁷Sr/⁸⁶Sr值偏高的特点,表明葡萄石是在淡水的作用下形成的。证实了灯影组在沉积过程中有过一次短暂暴露过程,这次沉积间断使灯影组暴露地表接受淡水淋滤,形成了小规模的岩溶现象,为葡萄石的形成创造了条件。这次短暂暴露过程对人们更好地理解葡萄石的成因及灯影组中部储层的形成有重要的意义。  相似文献   

Origin and Evolution of Silicic Magmatism at Yellowstone Based on Ion Microprobe Analysis of Isotopically Zoned Zircons   总被引：5，自引：0，他引：5  

Bindeman  Ilya N.; Fu  Bin; Kita  Noriko T.; Valley  John W. 《Journal of Petrology》2008,49(1):163-193

The origin of large-volume Yellowstone ignimbrites and smaller-volumeintra-caldera lavas requires shallow remelting of enormous volumesof variably ¹⁸O-depleted volcanic and sub-volcanic rocks alteredby hydrothermal activity. Zircons provide probes of these processesas they preserve older ages and inherited ¹⁸O values. This studypresents a high-resolution, oxygen isotope examination of volcanismat Yellowstone using ion microprobe analysis with an averageprecision of ± 0·2 and a 10 µm spot size.We report 357 analyses of cores and rims of zircons, and isotopeprofiles of 142 single zircons in 11 units that represent majorYellowstone ignimbrites, and post-caldera lavas. Many zirconsfrom these samples were previously dated in the same spots bysensitive high-resolution ion microprobe (SHRIMP), and all zirconswere analyzed for oxygen isotope ratios in bulk as a functionof grain size by laser fluorination. We additionally reportoxygen isotope analyses of quartz crystals in three units. Theresults of this work provide the following new observations.(1) Most zircons from post-caldera low-¹⁸O lavas are zoned,with higher ¹⁸O values and highly variable U–Pb ages inthe cores that suggest inheritance from pre-caldera rocks exposedon the surface. (2) Many of the higher-¹⁸O zircon cores in theselavas have U–Pb zircon crystallization ages that postdatecaldera formation, but pre-date the eruption age by 10–20kyr, and represent inheritance of unexposed post-caldera sub-volcanicunits that have ¹⁸O similar to the Lava Creek Tuff. (3) Youngand voluminous 0·25–0·1 Ma intra-calderalavas, which represent the latest volcanic activity at Yellowstone,contain zircons with both high-¹⁸O and low-¹⁸O cores surroundedby an intermediate-¹⁸O rim. This implies inheritance of a varietyof rocks from high-¹⁸O pre-caldera and low-¹⁸O post-calderaunits, followed by residence in a common intermediate-¹⁸O meltprior to eruption. (4) Major ignimbrites of Huckleberry Ridge,and to a lesser extent the Lava Creek and Mesa Falls Tuffs,contain zoned zircons with lower-¹⁸O zircon cores, suggestingthat melting and zircon inheritance from the low-¹⁸O hydrothermallyaltered carapace was an important process during formation ofthese large magma bodies prior to caldera collapse. (5) The¹⁸O zoning in the majority of zircon core–rim interfacesis step-like rather than smoothly inflected, suggesting thatprocesses of solution–reprecipitation were more importantthan intra-crystalline oxygen diffusion. Concave-downward zirconcrystal size distributions support dissolution of the smallercrystals and growth of rims on larger crystals. This study suggeststhat silicic magmatism at Yellowstone proceeded via rapid, shallow-levelremelting of earlier erupted and hydrothermally altered Yellowstonesource rocks and that pulses of basaltic magma provided theheat for melting. Each post-caldera Yellowstone lava representsan independent homogenized magma batch that was generated rapidlyby remelting of source rocks of various ages and ¹⁸O values.The commonly held model of a single, large-volume, super-solidus,mushy-state magma chamber that is periodically reactivated andproduces rhyolitic offspring is not supported by our data. Rather,the source rocks for the Yellowstone volcanism were cooled belowthe solidus, hydrothermally altered by heated meteoric watersthat caused low ¹⁸O values, and then remelted in distinct pocketsby intrusion of basic magmas. Each packet of new melt inheritedzircons that retained older age and ¹⁸O values. This interpretationmay have significance for interpreting seismic data for crustallow-velocity zones in which magma mush and solidified areasexperiencing hydrothermal circulation occur side by side. Newbasalt intrusions into this solidifying batholith are requiredto form the youngest volcanic rocks that erupted as independentrhyolitic magmas. We also suggest that the Lava Creek Tuff magmawas already an uneruptable mush by the time of the first post-calderaeruption after 0·1 Myr of the climactic caldera-formingeruption. KEY WORDS: Yellowstone; oxygen isotopes; geochronology; isotope zoning; zircon; U–Pb dating; caldera; rhyolite; ion microprobe  相似文献   

Effects of environmental oxygen deficiency on embryos and larvae of bay scallop,Argopecten irradians irradians     

Wang Chun-de  Zhang Fu-sui 《中国海洋湖沼学报》1995,13(4):362-369

The experimental results showed that: 1) The embryonic development of bay scallop is inhibited at a dissolved oxygen range of 1.38–3.64×10⁻³ at 23°C, and completely blocked below the lower limit. 2) The tolerance of larvae to anoxia increased with larval sizes and was related to their oxygen debt. 3) The scallop larvae exhibited specific behavioral responses to oxygen deficiency, which finally led to velum disintegration and larval death. The possible relationship between environmental oxygen deficiency and the disease of disintegration of the larval velum is also discussed. In this study, considerable oxygen debt was found in bay scallop larvae, which was greater in small animals. Based on the works of previous authors, a new concept is proposed for the estimation of oxygen debt, namely, the compensatory rate of oxygen debt (CROD). This can be used in intra—or interspecific comparison of oxygen debt. The results can be helpful in the management of water quality and for the prevention of larval diseases encountered in scallop culture. Contribution No. 2167 from the Institute of Oceanology, Chinese Academy of Sciences.  相似文献   

Late-glacial climatic oscillations as recorded in Swiss lake sediments     

A. F. Lotter Eawag  U. Eicher  U. Siegenthaler  H. J. B. Birks 《第四纪科学杂志》1992,7(3):187-204

Regional pollen assemblage zones for the late-glacial period of the Swiss Plateau are introduced and defined. They include four major zones (Artemisia, Juniperus—Hippophaë, Betula, Pinus PAZ) with several subzones. Pollen and oxygen-isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000-9500 yr BP. The first oscillation, termed the Aegelsee fluctuation, occurs shortly before 12 000 yr BP and varve counts suggest its duration was ca. 100 yr. It is characterised by a short decrease in the oxygen isotopes as well as a short increase in NAP associated with a depression in birch pollen values. The second oscillation, which occurs in the δ¹⁸O record shortly before the deposition of the Laacher See Tephra (ca. 11 000 yr BP), is termed the Gerzensee fluctuation. It occurs during a pine-dominated phase and its vegetational effects cannot be determined palynologically. The most prominent regressive phase is the Younger Dryas biozone (ca. 10 700-10 000 yr BP) characterised by an increase in heliophilous NAP and low δ¹⁸O values. The Younger Dryas biozone can often be subdivided palynologically into two parts: a first part rich in grasses and juniper and a second part with higher Filipendula and birch values. During the Preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios. Comparison of the Swiss oxygen isotope profiles with the Greenland Dye 3 record suggests that not only the three major shifts in the δ¹⁸O curves but also the minor ones are closely comparable, suggesting some common climatic control.  相似文献   

用瞬变电磁法探测灰岩溶洞   总被引：4，自引：0，他引：4  

薛国强  宋建平  马宇  全红娟 《地球科学与环境学报》2003,25(2):50-53

为了查明高速公路设计段地下灰岩溶洞的发育情况,运用大回线源瞬变电磁法在指定场地进行了探测。采用线性数字滤波技术进行正演模拟,采用改进的阻尼最小二乘可行方向法对资料进行反演计算,经过资料处理,查出地下灰岩溶洞的赋存位置,所解释的结果得到钻孔验证,效果很好。瞬变电磁探测技术的成功应用,很好地解决了高速公路设计中遇到的疑难地质问题。  相似文献