西藏阿里札达盆地下更新统香孜组地层厘定与层序地层划分

根据札达盆地香孜组河湖相地层剖面的接触关系、沉积旋回、沉积体系和岩相岩性特征,可将札达盆地下更新统香孜组河湖相地层划分为2个沉积相、3个岩段。香孜组一、二岩段为一套砾岩夹砂岩的粗碎屑岩,属典型的冲（洪）积扇沉积物;第三岩段为砾岩与砂岩互层,属冰水冰缘相沉积。ESR法和古地磁法测年结果表明,札达盆地香孜组河湖相地层的形成时代为早更新世早期（2．68—1．36Ma）。札达盆地为一同生断陷盆地,在后期重新复活的过程中,盆地只经历了冲积体系域和水进体系域。冲积体系域形成于札达盆地早更新世早期重新复活层序发育的早、中期,水进体系域形成于札达盆地早更新世早期重新复活层序发育的晚期。     

论杨氏东方翼龙在翼手龙类的系统位置

本文记述了一件采自辽西北票四合屯义县组下部东方翼龙的新标本。通过与正型标本的比较,证明东方翼龙为一有效的属,隶属于梳颌翼龙科。根据对新标本的研究,东方翼龙的修订特征应为:两翼展宽不超过1.25m,尺骨与飞行指的第二指节及胫骨几乎等长,第三足庶骨与胫骨长度之比约为0.40。论杨氏东方翼龙在翼手龙类的系统位置@吕君昌$中国地质科学院地质研究所!北京,100037 @高春玲$大连自然博物馆!116023 @孟庆金$大连自然博物馆!116023 @刘金远$大连自然博物馆!116023 @季强$中国地质科学院地质研究所!北京,100037…     

论杨氏东方翼龙在翼手龙类的系统位置

本文记述了一件采自辽西北票四合屯义县组下部东方翼龙的新标本。通过与正型标本的比较,证明东方翼龙为一有效的属,隶属于梳颌翼龙科。根据对新标本的研究,东方翼龙的修订特征应为:两翼展宽不超过1.25m,尺骨与飞行指的第二指节及胫骨几乎等长,第三足庶骨与胫骨长度之比约为0.40。论杨氏东方翼龙在翼手龙类的系统位置@吕君昌$中国地质科学院地质研究所!北京,100037 @高春玲$大连自然博物馆!116023 @孟庆金$大连自然博物馆!116023 @刘金远$大连自然博物馆!116023 @季强$中国地质科学院地质研究所!北京,100037…     

西藏阿里札达盆地上新统中犀类化石的发现及意义

首次在西藏阿里札达盆地上新世河湖相沉积地层中发现了犀类化石,对其基本特征进行了描述,初步鉴定为犀类额鼻角犀亚科第三蹠骨化石,在同一层位中还采集了大量孢粉、微体古生物和植物化石.结合区域地质特征和产出犀类化石地层的沉积学特征等的分析,认为札达盆地上新世时代表着温暖湿润向寒冷潮湿-温和干旱的气候变化过程.这一发现有助于进一步认识青藏高原新近纪上新世的生物演化、气候变化和构造活动,为研究青藏高原新近纪以来的生物进化、湖泊与河流演化、气候变化、古地理与古环境变迁,以及新生代地层的划分对比等提供了新资料.     

西藏阿里札达盆地上新世-早更新世河湖相沉积中两个不整合面的发现及意义

通过札达盆地河湖相地层的野外实测剖面和地质调查,结合前人资料,根据沉积岩性、不整合面、所含化石、固结程度和岩相变化,初步将这套水平产出、原顶底及接触关系不明的新近纪上新世-第四纪早更新世河湖相地层,划分为1个群、3个组、2次构造运动(不整合).从新到老为下更新统香孜组(Qp1x)和上新统古格群(N2gg),其中后者又细分为上新统札达组(N2 2z)和上新统托林组(N 1 2t).河湖相沉积中香孜组与札达组、札达组与托林组之间2个不整合面的发现和象泉运动与古格运动2次构造运动的确定,为研究青藏高原隆升过程、该区新近纪以来湖泊与河流演化、气候变化、古地理变迁和环境演化,以及新近系、第四系地层划分等提供了新资料.     

西藏札达盆地上新统一早更新统河湖相地层多重地层划分与对比

根据札达盆地河湖相地层实测剖面中的接触关系、沉积旋回、沉积体系、岩相、岩性、古生物特征和ESR、古地磁测年结果,笔者对札达盆地上新统一早更新统河湖相地层进行了重新划分和时代确定。结合该套河湖相沉积的岩石地层、生物地层、年代地层、磁性地层、层序地层和地质构造事件,对札达盆地上新统一早更新统河湖相地层进行了多重地层的划分与对比。将札达盆地河湖相地层划分为3个组、4个沉积相、7个沉积亚相、11个岩性段。由新到老划分为：早更新统香孜组（Qp^1-1X）、上新统古格组（N22g）和上新统托林组（N2^1t）。     

西藏阿里札达盆地上新世-早更新世河湖相沉积中两个不整合面的发现及意义

通过札达盆地河湖相地层的野外实测剖面和地质调查，结合前人资料，根据沉积岩性、不整合面、所含化石、固结程度和岩相变化，初步将这套水平产出、原顶底及接触关系不明的新近纪上新世-第四纪早更新世河湖相地层，划分为1个群、3个组、2次构造运动(不整合)。从新到老为下更新统香孜组(QP^1x)和上新统古格群(N2gg)，其中后者又细分为上新统札达组(N3^2z)和上新统托林组(N2^1t)。河湖相沉积中香孜组与札达组、札达组与托林组之间2个不整合面的发现和象泉运动与古格运动2次构造运动的确定，为研究青藏高原隆升过程、该区新近纪以来湖泊与河流演化、气候变化、古地理变迁和环境演化，以及新近系、第四系地层划分等提供了新资料。     

西藏阿里札达盆地上新世—早更新世河湖相沉积中两个不整合面的发现及意义

通过札达盆地河湖相地层的野外实测剖面和地质调查,结合前人资料,根据沉积岩性、不整合面、所含化石、固结程度和岩相变化,初步将这套水平产出、原顶底及接触关系不明的新近纪上新世—第四纪早更新世河湖相地层,划分为1个群、3个组、2次构造运动(不整合)。从新到老为下更新统香孜组(Qp1x)和上新统古格群(N2gg),其中后者又细分为上新统札达组(N22z)和上新统托林组(N12t)。河湖相沉积中香孜组与札达组、札达组与托林组之间2个不整合面的发现和象泉运动与古格运动2次构造运动的确定,为研究青藏高原隆升过程、该区新近纪以来湖泊与河流演化、气候变化、古地理变迁和环境演化,以及新近系、第四系地层划分等提供了新资料。     

新疆拜城地区叶肢介化石

新疆拜城地区叶肢介化石有6科,9属,19种(包括3个新种).标本采自卡拉苏河、公安煤矿及老虎台的俄霍布拉克群,以及卡拉苏河的恰克马克组.     

辽西义县组奔龙类化石一新种

在辽宁西部义县头台的义县组中新发现的1件奔龙类化石标本，显示出许多中国鸟龙属(Sinornithosaurus)所具有的特征，如上颌骨眶前窝侧面具有装饰性凹坑、前颌骨齿无边缘小锯齿、齿骨后缘二分叉、指节Ⅲ-1略长于指节Ⅲ-2的2倍、踱骨Ⅲ部分窄踱型形态等。但其头骨的部分骨骼与千禧中国鸟龙(S．millenii)有明显的区别：前颌骨主体部分相对较高，其长仅稍大于其高，前颌骨角大，前颌骨上颌突与鼻突均很长，上颌骨不参与外鼻孔的构成，上颌骨窗相对较小且为圆形，方颧骨上升突明显长于颧骨突，齿骨长高之比小等。此外，新标本肠骨的耻骨柄前后方向的宽度小于髋臼宽度。这些不同之处表明，义县头台的标本应为中国鸟龙属另一新种，将其命名为郝氏中国鸟龙(新种)(S．haoiana sp．nov.)。     

Isotope geochemistry (S,C, O,Sr, Pb) of the Chaudfontaine mineralization (Belgium)

Investigations on S, C, O, Sr, and Pb isotopes in ores, gangue, and country rocks of the Chaudfontaine ore deposit confirm that interbedded barite and white sparry calcites are cogenetic. They emphasize the marine origin of S and the nonmarine origin of the metals. They underline the important role played by the bacterial reduction at the site of deposition. Hypotheses concerning the source of the metals and the nature of the brines involved in their transportation are briefly discussed.     

Anomiid (bivalve) bioerosion on Pleistocene pectinid (bivalve) shells,Rhodes, Greece

A trace fossil, Centrichnus eccentricus, was found beneath a saddle oyster (Anomia ephippium) that was preserved undisturbed on its substratum (a shell of Pecten jacobaeus), at the site of attachment of the calcified byssus.     

Trace elements (REE) and isotopes (O,C, Sr) to characterize the metasomatic fluid sources: evidence from the skarn deposit (Fe,W, Cu) of Traversella (Ivrea,Italy)

The skarn complex of Traversella was formed at the expense of various rock types (calcic hornfels, gneiss, dolomitic marble) occurring in the contact aureole of the dioritic intrusion of Traversella (30±5 Ma). Application of phase equilibria has fixed the temperature of the primary stage of skarn formation between 550° C to 625° C. Similar applications indicate a larger range of temperature (525° C to 300° C) for the secondary stage. The different types of skarn (primary stage) are enriched in REE relative to the corresponding precursor rock (T.R.=126 ppm (protolith) to 228 ppm (inner zone) for the skarn on gneisses; T.R.=14 ppm to 71 ppm for the skarn on calcic hornfelses; T.R.=12 ppm to 200 ppm for the skarn on dolomitic marbles), but all the inner zones of these different types of skarn show a similar REE distribution with a slight LREE fractionation and no Eu anomaly. It is inferred that the primary metasomatic fluid has a parallel REE pattern. The oxygen isotope composition of water in equilibrium with the early stage of skarn at T=600° C ranges from 8.3 per mil to 8.9 per mil. At the beginning of the first hydroxylation stage (secondary stage), the fluid σ ¹⁸O remains in the range observed in the primary stage but within it, there is a sharp decrease from 8.0 per mil to 5.0 per mil. During the sulphidation stage, the fluid σ ¹⁸O decreases more gradually from 5.0 per mil to 3.0 per mil. The I _Sr of the early skarn silicates ranges from the values observed in the dolomitic marbles (0.70874 to 0.70971) to the I _Sr of the intrusion (0.70947 to 0.71064). During the secondary stage, there is a progressive increase of the minerals I _Sr up to 0.71372. The REE pattern of the primary metasomatic fluid does not put any precise constraint on the primary fluid source. On the other hand, both stable and radiogenic isotopes suggest that the early high-temperature metasomatic fluid was isotopically equilibrated with the dioritic intrusion. This implies that this early fluid is either exsolved from the crystallizing intrusion or a metamorphic water previously equilibrated with the intrusion. During the secondary stage, the replacement of the early anhydrous phases by hydrated parageneses is accompanied by the mixing with meteoric fluid as indicated by stable (σ ¹⁸O) and radiogenic (⁸⁷Sr/⁸⁶Sr) isotopes.     

Relationships Between Geochemical Parameters (pH, DOC, SPM, EDTA Concentrations) and Trace Metal (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) Concentrations in River Waters of Texas (USA)

Water samples from eight major Texas rivers were collected at different times during 1997–1998 to determine the dissolved and particulate trace metal concentrations, expected to show differences in climate patterns, river discharge and other hydrochemical conditions, and human activities along the different rivers. Specifically, two eastern Texas rivers (Sabine, Neches) lie in a region with high vegetation, flat topography, and high rainfall rates, while four Central Texas rivers (Trinity, Brazos, Colorado, and San Antonio) flow through large population centers. Relatively high dissolved organic carbon (DOC) concentrations in the eastern Texas rivers and lower pH led to higher Fe and Mn concentrations in river waters. The rivers that flow through large population centers showed elevated trace metal (e.g., Cd, Pb, Zn) concentrations partly due to anthropogenically produced organic ligands such as ethylenediaminetetraacetic acid (EDTA) present in these rivers. Trace metal levels were reduced below dams/reservoirs along several Texas rivers. Statistical analysis revealed four major factors (suspended particulate matter [SPM], EDTA, pH, and DOC) that can explain most of the observed variability of trace metal concentrations in these rivers. SPM concentrations directly controlled particulate metal contents. Variation in pH correlated with changes of dissolved Co, Fe, Mn, and Ni, and particulate Mn concentrations, while DOC concentrations were significantly related to dissolved Fe concentrations. Most importantly, it was found that, more than pH, EDTA concentrations exerted a major control on dissolved concentrations of Cd and Zn, and, to a lesser extent, Cu, Ni, and Pb.     

Johillerit,Na(Mg,Zn)3 Cu(AsO4)3, ein neues Mineral aus Tsumeb,Namibia

Zusammenfassung Die chemische Analyse des neuen Minerals Johillerit mit der Elektronenmikrosonde ergab: Na₂O 5,4, MgO 18,3, ZnO 5,4, CuO 15,8 und As₂O₅ 55,8, Summe 100.7%. Aus diesem Ergebnis wurde die idealisierte Formel Na(Mg, Zn)₃ Cu(AsO₄)₃ abgeleitet. Johillerit ist monoklin mit der RaumgruppeC2/c. Die Gitterkonstanten sind:a=11,870 (3),b=12,755 (3),c=6,770 (2) , =113,42 (2)°,Z=4. Die stärksten Linien des Pulverdiagramms sind: 4,06 (5) (22 ), 3,50 (4) (310), 3,25 (8) (11 ), 2,75 (10) (330, 240), 2,64 (5) (311, 13 , 40 ), 1,952 (4) (13 , 35 ), 1,682 (4) (20 , 460), 1,660 (5) (40 , 71 , 550, 64 ), 1,522 (4) (442, 153, 13 ). Es bestehen enge strukturelle Beziehungen zwischen Johillerit und O'Danielit, Na(Zn, Mg)₃H₂(AsO₄)₃, sowie einigen synthetischen. Verbindungen.Johillerit ist violett durchscheinend. Die Spaltbarkeit nach {010} ist ausgezeichnet und nach {100} und {001} gut.H (Mohs)3.D=4,15 undD _X =4,21 g·cm^–3. Das Mineral ist optisch zweiachsig positiv, 2V80 (5)°. Die Werte der Lichtbrechung sindn =1,715 (4),n =1,743 (4) undn =1,783 (4). Die Auslöschung istn b und auf (010)n c16°. Johillerit ist stark pleochroitisch mit den AchsenfarbenX=violett-rot,Y = blauviolett undZ = grünblau. Das neue Mineral kommt in radialstrahligen Massen gemeinsam mit kupferhaltigem Adamin und Konichalcit in zersetzem Kupfererz von Tsumeb, Namibia, vor. Die Benennung erfolgte nach Prof. Dr.J.-E. Hiller (1911–1972).

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Johillerite, Na(Mg, Zn) ₃ Cu(AsO ₄ ) ₃ , a new mineral from Tsumeb, Namibia

Summary Electron microprobe analysis of the new mineral johillerite gave Na₂O 5.4, MgO 18.3, ZnO 5.4, CuO 15.8, and As₂O₅ 55.8, total 100.7%. From this result, the ideal formula is given as Na(Mg, Zn)₃ Cu(AsO₄)₃. Johillerite crystallizes monoclinic,C2/c. The unit cell dimensions are:a=11.870(3),b=12.755 (3),c=6.770 (2) , =113.42 (2)°,Z=4. The strongest lines on the X-ray powder diffraction pattern are: 4,06 (5) (22 ), 3,50 (4) (310), 3,25 (8) (11 ), 2,75 (10) (330, 240), 2,64 (5) (311, 13 , 40 ), 1,952 (4) (13 , 35 ), 1,682 (4) (20 , 460), 1,660 (5) (40 , 71 , 550, 64 ), 1,522 (4) (442, 153, 13 ). There is a close relationship between johillerite, o'danielite, Na(Zn, Mg)₃H₂(AsO₄)₃, and some synthetic compounds. Johillerite is violet in colour, transparent. Cleavage is {010} perfect, {100} and {001} good.H (Mohs)3.D=4.15 andD _X =4.21 g·cm^–3. The mineral is optically biaxial positive, 2V80 (5)°. The refractive indices are:n =1.715 (4),n =1.743 (4),n =1.783 (4). The extinction isn b and on (010)n c16°. Strongly pleochroic with axial coloursX=violet-red,Y=bluish violet andZ=greenish blue. The new mineral was found in radiated masses together with cuprian adamite and conichalcite in an oxidized copper ore from Tsumeb, Namibia. It is named in honour of Prof. Dr.J.-E. Hiller (1911–1972).

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~(40)Ar-~(39)Ar GEOCHRONOLOGY OF THE SUTURE ZONE, LADAKH, INDIA

~(40)Ar-~(39)Ar GEOCHRONOLOGY OF THE SUTURE ZONE, LADAKH, INDIA1　TalatAhmedetal.GeochemicalJournal,1999. 2　HoneggerK ,etal.EarthandPlanetaryScienceLetters,1982 ,6 0 :2 53. 3　SearleMP ,etal.GeologicalSocietyofAmericaBulletin ,1987,98:6 78. 4　SharmaK ,K .PhysicsandChemistryoftheEarth ,1990 ,17( 2 ) :133. 5　Venkatesan ,etal.EarthandPlanetSciLett,1993,119:181.…     

Chemical and isotopic (C, O, Sr, Nd) characteristics of the Xiluvo carbonatite (central-western Mozambique)

Summary The Xiluvo complex of central Mozambique is made up of coarse- to fine-grained calciocarbonatites (sövites and alvikites), heavily altered lamprophyres and syenitic rocks that intruded the Precambrian basement ca. 120Ma ago. The carbonatites have fractionated rare earth element patterns (chondrite-normalized La/Yb=30–80) and markedly negative Rb, K, P, Zr and Ti anomalies in mantle-normalized incompatible element diagrams. The ¹⁸O (+7 to +8), ¹³C (–5), and the age-corrected ⁸⁷Sr/⁸⁶Sr (0.7032–0.7033) and ¹⁴³Nd/¹⁴⁴Nd (0.51263–0.51262) indicate an origin in the mantle. A few carbonatitic samples have higher ¹⁸O (+13), indicating interaction with high-¹⁸O crust or late-stage fluids. The chemical and isotopic compositions of the Xiluvo carbonatites and nearby carbonatites of similar age in Malawi indicate very similar sources, characterized by time-integrated depletion of Rb with respect to Sr and of Sm with respect to Nd. These characteristics point to a source similar in many respects to those of other East African carbonatites and to those of some ocean island basalts, with the additional influx of components possibly located in the African lithospheric mantle.