Compositions of early Islamic glass along the Iranian Silk Road

The composition of archaeological glass reflects the geochemical nature of its raw materials. To determine the origins and distribution of early Islamic glasses from Iran, a set of 169 glass samples from five different sites was analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of 58 elements. The glasses were classified into six different plant ash glass groups, three of which were attributed to a Mesopotamian origin, while three further groups are presumed to represent regional Iranian productions. The ratios of MgO/CaO and K₂O/P₂O₅ of the different groups reflect variations in the plant ash component. Minor elements Cr, Ti, Zr, La and Th and their ratios proved effective in distinguishing the base glass types. Mapping their frequency across the Iranian plateau revealed the relative movement of glass and likely source areas. The decline in the frequency of glass types with elevated Cr/La ratios east of the Zagros Mountain range confirms that elevated Cr/La ratios together with an augmentation of the magnesium levels are features of Mesopotamian glass production apparently inherited from the geochemical environment of the Euphrates and Tigris river valleys. Some exceptionally clean Mesopotamian glasses made from a quartz-rich silica with low levels of accessory minerals are consistent with ninth-century glass from Samarra, which was evidently traded widely along the Silk Road network. No evidence of local glass production was detected in Nishapur. The Iranian groups were produced from a quartz-rich silica source, high in thorium but with different zirconium contents resulting in different Th/Zr ratios. Aluminium concentrations tend to increase from west to east, with the highest values found among glass assemblages from Central Asia.     

Geochemical behaviors of different element groups during shale weathering at the Susquehanna/Shale Hills Critical Zone Observatory

Major and trace element concentrations were measured in bedrock, regolith and stream sediments from a first-order catchment developed entirely on grey shale in central Pennsylvania, USA. These elements can be classified into five major groups based on statistical data analysis. The presence of different elemental groups is due to the mineralogical origin, cycling processes, and geochemical properties of these elements during soil formation. A better understanding of the behaviors of these elements during chemical weathering would allow for their possible use as natural tracers in Critical Zone processes.     

Isotopic-Geochemical Features of Zircon and Its Significance for Reconstructing the Geological History of Paleoarchean Granulites in the Ukrainian Shield

This paper presents the results of a complex study (morphology of grains, internal texture in cathodoluminescence and backscattered electrons, microprobe analysis, Lu–Hf data) of five groups (generations) of zircon crystals differing in age and separated from the same granulite sample pertaining to the Bug River Complex of the Ukrainian Shield. The data show that the oldest zircon crystals of the first group (3.74 Ga in age) are xenogenic and initially crystallized from a granitic melt; zircon of the second group (3.66 Ga) formed from a mafic melt contaminated by felsic country rocks. The third group (3.59 Ga) is represented by zircons that formed about 100 Ma later than the second group under conditions of granulite-facies metamorphism and with the participation of fluid-saturated anatectic melt. Two Paleoproterozoic zircon groups (~2.5 and 2.1 Ga) also formed under granulite-facies conditions; to a certain extent, their structure and composition were controlled by fluid. The geochemistry of all zircon generations provides evidence for their crystallization in the continental crust, but from the sources differing in the contribution of mantle-derived material and in oxygen fugacity.     

Fluorescence spectral analysis of resinite macerals from coals of the Hanna Formation, Wyoming, U.S.A.

Flourescence spectral analysis indicates that resinite macerals from Tertiary Hanna Formation coals (Hanna Coal Field, southcentral Wyoming, U.S.A.) can be separated into five distinct groups. The first resinite group fluoresces a a medium green (in blue light); its average spectral maximum occurs at or below 440 mm with a red/green quotient of 0.22. The second resinite group fluoresces yellow-green with an average spectral maximum of 500 nm and a red/green quotient of 0.53. The third resinite group displays a yellow fluorescence having an average spectral maximum of 580 nm and a red/green quotient of 0.86. The fourth resinite group fluorescence orange-brown having an average spectral maximum of 610 nm and a red/green quotient of 1.20. These four groups mostly occur as primary globular resinites exhibiting scratches and fractures, indicating that they are brittle, solid substances. Primary cell-filling and secondary fracture-filling resinites also occur in these four groups. The fifth group only occurs as a secondary void-filling material and lacks evidence of br of brittle properties. It fluoresces a reddish-brown, has a spectral maximum at 690 nm, and a red/green quotient of 1.54. The fifth group has properties resembling exsudatinite. The five resinite groups can be separated on the basis of their nine spectral properties alone, without qualitative petrographic interpretation.The relative quantities of the five resinite groups vary among Hanna Formation coals. The origins of these five resinite groups are probably related to their botanical properties and pre- and post-depossitional conditions. Overall, Hanna Formation resinites have petrographic characteristics similar to other North American resinites; however, only four resinite groups have been distinguished in in certain coals from Utah and New Mexico (U.S.A.), and western Canada.     

Ceramic production during the Middle Horizon: Wari and Tiwanaku clay procurement in the Moquegua Valley,Peru

As the only place simultaneously occupied by the Middle Horizon (A.D. 600–1000) Andean states, the Tiwanaku and the Wari, the Moquegua Valley in southern Peru is of critical importance to understanding relations between the two states. Visual studies of Tiwanaku and Wari ceramics in the valley have elucidated differences in form and decoration. The procurement of raw clays was central to the production of these ceramics, and understanding where people procured their clay may provide insight into the social and economic interactions between these two states. Survey of the Moquegua Valley indicates the extensive availability of raw clays. Results of laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) analyses of clays indicate that there is heterogeneity in the chemical signature of the valley's clays and that at least five different clay groups can be distinguished. Comparison of these clays with LA‐ICP‐MS analysis of ceramics from a Tiwanaku site and a Wari site demonstrates that although Tiwanaku and Wari colonists in Moquegua used locally available clays during the Middle Horizon, the clay sources exploited by potters from each state were different and derived from areas located within their respective middle and upper valley territories. This information provides a basis for future chemical analysis of ceramics from the Moquegua Valley and improved understanding of past social and economic interactions. © 2009 Wiley Periodicals, Inc.     

滇西澜沧江南段小湾地区崇山岩群LA-ICP-MS锆石U-Pb年龄及其地质意义

滇西崇山岩群一直被认为是元古宙的大陆地壳-结晶基底,但至今无精确的年龄依据。对滇西澜沧江南段小湾地区崇山岩群的5件样品(糜棱岩化斜长变粒岩、黑云斜长角闪岩、片麻岩、糜棱岩化花岗质片麻岩、糜棱岩化黑云斜长变粒岩)进行锆石U-Pb定年。5件样品的锆石阴极发光图像显示,锆石有明显的生长振荡环带,指示岩浆成因。5件样品锆石的206Pb/238U年龄加权平均值分别为239.4±3.8Ma、248.4±4.3Ma、237.1±5.7Ma、268.7±3.2Ma、238.4±5.5Ma。根据野外地质特征和年龄数据,认为滇西澜沧江南段小湾地区崇山岩群是不同时代、不同岩性的岩体/地层(二叠系、三叠系)经后期变质作用形成的一套正变质岩,并不全是古老基底岩石出露。     

五种降水产品在疏勒河上游山区和中下游月尺度降水的适用性对比研究

降水产品为理解降水时空分布提供了新的视角,然而其在不同地区适用性差异很大,目前对不同降水产品在西北内陆河流域上游山区和中下游平原适用性的对比研究还十分有限。利用疏勒河流域及周边9个国家气象站2001-2013年和4个山区自建气象站2008-2013年降水观测数据,基于皮尔逊相关系数（R）、均方根误差（RMSE）、平均绝对误差（MAE）和相对偏差（BIAS）指标,对CMFD、ERA-Interim、GPCC、GPCP V2.3和JRA-55共五种常用降水产品的月尺度降水数据在疏勒河上游山区和中下游平原区的适用性进行了评估对比,结果表明：五种降水产品都可以较好地模拟疏勒河流域多年平均降水的空间分布,总体来说,降水产品在上游的评估的相对误差优于中下游,但绝对误差比中下游大,这与上游降水远大于中下游有关。各产品在上游和中下游的精度排序结果一致,均为CMFD > GPCC > ERA-Interim > GPCP V2.3 > JRA-55。CMFD效果最佳可能与融合了中国更多的地面降水资料有关,其在自建站的效果也表现最佳。不同产品在疏勒河上游山区和中下游月尺度的降水评估中表现较好,但尚不能满足流域水文过程分析和模拟的需要。     

Cycles of alkaline magmatism

Geochronological data (～1800 dates) have been analyzed by the probabilistic statistical analysis of samplings of different subalkaline and alkaline rocks through the whole of geological time. The distribution of five groups of subalkaline and alkaline rocks within the Late Archean-Phanerozoic are strictly controlled by mantle cycles, which were distinguished from data on the upper mantle magmatic rocks. Since high alkali rocks are plume related, their universal participation in each of the revealed mantle cycles emphasizes the importance of this magmatism in the evolution of the crustal-mantle system. The initial Sr and Nd isotope ratios are subdivided into two groups: with mantle and crustal signatures. Mantle isotope ratios are typically observed throughout the entire geological interval of dated rocks, while the role of crustal isotope signatures increases from the Archean to Phanerozoic, reflecting the increasing the role of fluids and crustal rocks in the magmatic processes during the generation of mantle magmas and their consolidation in the crust. Since alkaline magmatic sources are formed during mantle metasomatism, which enriched the magma generation zones in incompatible elements, the repeated occurrence of this process in separate mantle zones may have lead to the anomalous accumulation of these elements, which should be reflected in the alkaline magmas.     

Palaeomagnetic and potassium‐argon dating studies of the Tasmanian Dolerites

The stable magnetizations of the Tasmanian Dolerites are shown to fall into two distinct groups depending upon their directions and the geographical region of the dolerites. It has been suggested that this could be a result of significant age differences between the dolerites of these groups. A series of K‐Ar determinations indicates that there is no detectable systematic age differences and the average of the five bodies dated is 170.5 ± 8.0 m.y. (not significantly different from previous K‐Ar dates from a single body). A re‐appraisal of the palaeomagnetic data, in the light of the distinct groupings of the directions, yields two significantly different pole positions‐ Lat 50.7°S, Long. 174.5°E (A_9r, = 5.2°) and Lat. 47.7 °S, Long. 123.5° (A₉₅ = 9.5°)’. The former of these is in excellent agreement with pole positions from other Lower to Middle Jurassic rocks of Australia but the significance of the latter remains obscure.     

Ferromanganese Crusts in the Central Basin,Sea of Japan

The paper presents a comparative analysis of ferromanganese crusts and concretions (FMC) recovered during the dredging of 14 seamounts in the Central Basin, Sea of Japan. The major rock-forming elements in FMC are Mn, Fe, and Si. In terms of the Mn content, the studied 53 samples are divided into four groups: (1) less than 10% (given than concentrations of 2–8% are lacking); (2) 10?25%; (3) 25?42%; and (4) 42?63%. The (Mn + Fe)/Si ratio increases from group 1 to group 4, and average value in them is 1.6, 2.5, 6.7, and 70.7, respectively. Taking Fe/Si and Mn/Si values into consideration, concretions of these groups belong to the following varieties: (1) ferrosiliceous; (2) mangano-ferrosiliceous; (3) siliceous-ferromanganese, and (4) manganiferous. The highest concentration of nonferrous metals is observed in FMC of groups 2 and 3. Their concentration is slightly lower in group 4 and very low in group 1. The internal structure of FMC in these groups is variable, suggesting their different formation settings. Crusts of group 1 were formed during the precipitation of Mn from a hydrothermal plume on the older ferrosiliceous crusts. Crusts of groups 2 and 3 were likely formed by the diffuse percolation of Mn-bearing hydrothermal solutions along fractures and weakened zones in volcanic rocks, with their subsequent cementation by manganiferous hydroxides from sedimentary or volcaniclastic deposits on seamounts. Crusts of group 4 were formed at sites of the hydrothermal solution discharge on the seafloor. FMC of different groups are recovered during the dredging of most volcanic seamounts in the Central Basin (Sea of Japan). Since the dredging is accomplished at a depth interval of a few hundreds of meters, the detection of concretions of a certain type is governed by the distance to the nearest hydrothermal source.     

从源到汇:大别造山带物源区与合肥盆地南缘中生代沉积耦合关系——来自碎屑锆石U-Pb年龄证据

形成于印支期的大别造山带和周缘中生代盆地构成了一级源汇系统,其中位于造山带北缘的合肥盆地中生代地层发育,且以盆地南缘出露最好,这为盆山源汇系统研究提供了理想的沉积记录。笔者从合肥盆地南缘采集了10个砂岩样品和1个砾岩样品,进行锆石U/Pb (LA-ICP-MS)定年分析,获得了742个有效年龄(置信度不小于85%),范围为113±3. 6-2983 Ma。这些碎屑锆石年龄谱可以被分为5个年龄段:113-137 Ma,峰值131 Ma; 184-273 Ma,峰值226 Ma; 274-517. 3 Ma,具有2个峰值280 Ma和474 Ma; 532-856. 6 Ma,具有3个峰值572 Ma、649 Ma和772 Ma; 1786-2600 Ma,具有2个峰值2035 Ma和2506 Ma。同时,总结了物源区大别造山带不同单元锆石U-Pb年龄特征。根据锆石U/Pb年龄和Th/U值,发现这5个年龄段比较准确地记录了物源区地质体,分别是早白垩世的岩浆岩、大别山高压—超高压变质岩、北淮阳的浅变质岩、北大别的正片麻岩和卢镇关群变质岩。根据锆石最小年龄,修正了合肥盆地南缘中生代地层格架,为源汇系统研究确立了时间框架。合肥盆地南缘中生代沉积可以分为4个演化阶段:晚三叠世瑞替期—早侏罗世辛涅缪斯期、中—晚侏罗世、早白垩世早期和早白垩世晚期,并据此确定了每个阶段主要物源区特征及其时空变化。碎屑锆石U/Pb年龄和Th/U值限定了大别造山带仅存在三叠纪的超高压变质作用,且超高压变质岩折返到地表的最早时间是晚三叠世瑞替期,大别造山带大陆岛弧发育的时间是新元古代。上述研究结果不仅为恢复大别造山带构造古地理做出了新的贡献,而且更为盆山源汇系统研究提供了一个实例。     

Y/Ho Ratios in the Late Cenozoic Basalts from the Eastern Tuva, Russia: An ICP-MS Study with Enhanced Data Quality

A set of forty seven Late Cenozoic basaltic rocks from the Eastern Tuva (southern Siberia, Russia) have been studied by ICP-MS using In as an internal standard. Yttrium and Ho concentrations, determined along with other trace elements, varied systematically from one analytical run to another and covered the entire charge-and-radius-controlled field within the range 24 < Y/Ho < 34, so obscuring any geochemical interpretation. A correction procedure was therefore developed in which the Y/Ho ratios were recalculated using concentrations of these elements determined in international and in-house reference materials (BHVO-1, AGV-1, BIR-1 and U-94-5). Statistical analysis of the recalculated data set revealed two groups of samples not related by their genesis but rather by their respective analytical runs. Fourteen samples originally analysed in five different runs were then re-measured by the same instrument in peak-hopping mode using only specific mass peaks (m/z = 89, 115 and 165). All of these samples yielded Y/Ho ratios in a narrow range between 29 and 31, thus illustrating how analytical problems in the determination of Y and Ho by routine ICP-MS procedures can be overcome. Finally, a mean value of Y/Ho = 30.3 ± 1.1 (1s) was derived for the basaltic rocks of the Eastern Tuva. This is close to the value of 28.8 accepted for chondrites and for ocean island basalts. Despite the uniform Y/Ho ratio, the element concentrations in basaltic rocks from the Eastern Tuva show systematic enrichment in heavy rare earth elements and yttrium from the Miocene to the Quaternary.     

Ore Group Classification - A Case Study from Ingaldhal Sulphide Deposit, Karnataka Craton, India

All varieties of base metal sulphide deposits may be classified using base metal ratios viz. Copper Ratio (CR=100Cu/{Cu+Zn}), Zinc Ratio (ZR=100Zn/{Zn+Pb}) and Lead Ratio (PR=100Pb/{Pb+Cu}). Based on this ore group classification an attempt has been made to identify ore groups present in the late Archaean volcanic associated Ingaldhal Sulphide Deposit (ISD) of Karnataka Craton. Using base metal ratios (CR, ZR and PR) five distinct fields are suggested: Cu, Cu-Zn, Cu-Zn-Pb, Zn-Cu and Zn-Cu-Pb/Zn-Pb-Cu with their associated geological and geochemical characteristics. A transitional change in the ore groups is observed from the North Block (Cu rich groups; CR>50) to South Block (Zn and Pb dominated groups; CR<50) and the Main Block is represented by all the five ore groups.This classification may be useful as a pointer in the exploration of polymetallic base metal deposits. Copper rich groups (Cu, Cu-Zn and Cu-Zn-Pb) exhibit high concentration of Bi and Co, and low CaO and Cd whereas the Zn rich groups (Zn-Cu and Zn-Cu-Pb/Zn-Pb-Cu) show high CaO and Cd, and low Bi and Co. The CR of most of the ore groups exhibit a sympathetic relation with Co and Ag. A preliminary attempt has been made for better understanding of ore group genesis of ISD by integrating ore group characteristics with deduced geothermometry.     

柴达木盆地原油碳同位素组成的主控因素与成因类型

对采集于柴达木盆地16个油田的40个原油进行了碳同位素测定,研究了它们碳同位素组成特征、主控因素及其成因类型。结果表明,柴达木盆地西部地区和北部地区原油碳同位素组成具有显著的差别,西部地区原油富集13C,北部地区原油富集12C。研究发现,成油环境(如盐度和湿度)是决定西部盐湖相原油碳同位素组成及其变化的主要因素,母源性质则控制了北部淡水湖沼相原油的碳同位素组成和变化。根据原油的碳同位素组成和Ph/nC₁₈比值特征,将柴达木盆地原油划分为五种成因类型。     

Field and Geochemical Studies of the Melilite-Bearing Arydzhangsky Suite,and an Overall Perspective on the Siberian Alkaline-Ultramafic Flood-Volcanic Rocks

This paper presents the first comprehensive geologic, petrographic, geochemical, and Sr- and Nd-isotopic study of the 350 m thick Arydzhangsky lava suite, the last suite in the entire north Siberian, flood-volcanic sequence to require study by modern methods. Within this sequence, only the Arydzhangsky Suite includes melilite-bearing lavas; it is composed of melanephelinites to limburgites (both melilite-bearing and melilite-free), with rare melilitites and picrites. The lavas contain from 0 to 60 vol% melilite, with MgO contents ranging from 5.7 to 29.5 wt%. Nonetheless, these compositionally diverse lavas are all quite similar in incompatible-element geochemistry. They are distinct from all other Siberian alkaline-ultramafic lavas and, among these lavas, show the most resemblance to the Yakutian kimberlites.

With this contribution, all of the north Siberian, alkaline-ultramafic lavas will have received equal geochemical and isotopic characterization. Five rock groups have been identified among them on the basis of distinctive rare-earth-element (REE) patterns: melilitite-related, melanephelinite-related, meymechite-related, trachybasalt-related, and ankaramite-related. The REE ratios and patterns that distinguish the groups have not evolved by fractionation, because they display no relation to MgO content. Judging from the isotopic data, crustal contamination had little influence on magma evolution. All rock groups, despite their geochemical dissimilarities, show close geochemical linkages among themselves, and significant geochemical similarity to kimberlites of the Yakutian province and ocean-island basalts (OIB). Thus, all of these continental and oceanic magmas may have originated in the same part of the mantle. Geochemical distinctions among the five rock groups could have been caused by various degrees of partial melting and differing amounts of dissolved volatiles.     

Hydrogeochemical peculiarities of the composition of nitric thermal waters in the Baikal Rift Zone

The chemical, gas, and isotopic compositions of nitric thermal waters in the Baikal Rift Zone are considered. It is shown that the behavior of sulfate and carbonate ions in hydrothermal systems is different, which indicates that they are of two different origins. The studied thermal waters are of five chemical types formed in different geologic conditions. Special attention is given to the genesis of hydrotherms, the geologic and geomorphologic conditions of their recharge, and their equilibrium with rocks. It has been established that most of chemical elements of the waters migrated from rocks, but a significant portion of them is bound by secondary minerals, which results in their deep differentiation, accumulation, or precipitation. Thus, the so-called redundant elements appear, which were earlier considered to be of mantle origin.     

Rb-Sr dating of alteration events in granitoids

Veins and other effects of low-grade metamorphism are often found in igneous rocks. A method for dating such veins is proposed. It is based on the presence of Ca-bearing, Rb-free minerals in the veins and their aureoles. The method is applicable if five conditions are satisfied. The effects of low-grade metamorphism on Rb-Sr dating of the emplacement (extrusion) age are also studied. Veins and their aureoles in granitoid rocks from Central Sweden are used as a working example. Two groups of vein ages were found, 1600-1500 Ma and 1250-1100 Ma, which coincide with the two known periods of tensional movements in the region. The ratio ⁸⁷Sr/⁸⁶Sr in the aureoles and their neighbourhood at the time of vein formation (Sr(a)) shows several different patterns. One with constant Sr(a), independent of the distance to the vein, indicates complete homogenization at the time of alteration. Another shows an increase in Sr(a) close to the vein, indicating that it was rejuvenated. Furthermore, the Sr ratio might determine whether an alteration effect could be of deuteric origin or not: deuteric effects should be characterized by a Sr(a) value equal to the initial Sr-isotope ratio.     

RQD应用与研究的回顾与展望

RQD是评价裂隙岩体质量的重要参数,它在岩体工程中被广泛采用,但经过长期的理论和实践工程师们认识到了RQD自身所存在的缺点和不足,并将RQD的缺点和不足总结为5点。但RQD仍然具有很强的生命力,从5个方面总结了近半个世纪以来人们对RQD的不断探索和研究的进程,并进一步指出了对RQD的拓宽和改进的主要研究方法和发展方向。     

A new approach for molecular characterisation of sediments with Fourier transform ion cyclotron resonance mass spectrometry: Extraction optimisation

Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) can begin to tease apart the molecular character of sedimentary organic matter (SOM). We therefore tested five different solvents (aqueous base, CHCl₃, MeOH, pyridine and water) for their ability to extract a representative fraction from two organic rich lacustrine sediments, Mangrove Lake, Bermuda (MLB) and Mud Lake, Florida (MLF). Following comparison using liquid state nuclear magnetic resonance spectroscopy (NMR) and negative ion mode electrospray ionization mass spectrometry (FTICRMS) we found that pyridine was the optimal solvent, extracting a more diverse (10–100× greater integration for carbonyl, amide and amine groups) and a larger number of peaks on average (1375–1450 vs. 380–1450). Comparison of the pyridine extracts between MLB, MLF and two organic poor sediments from the Mississippi River Delta and Bayou Grande (Pensacola, FL) showed that only 4.9% of the molecular formulae were common to all four and that unique formulae made up the highest proportion of the assignments. The use of pyridine for extracting immature (Holocene) SOM for FTICRMS analysis can therefore be widely applied to immature sediments and produce representative spectra.     

U-Th-Pb systematics of zircon inclusions in rock-forming minerals: A study of armoring against isotopic loss using the Sherman Granite of Colorado-Wyoming,USA

Zircon inclusions were separated from the five major rock-forming minerals of the Sherman Granite of southern Wyoming, in order to evaluate the degree of discordance as a possible function of host minerals. U-Th-Pb isotopic ratios were determined for two size fractions of zircon inclusions from each mineral, plus five size fractions from the bulk rock. Isotopic data from the inclusions have more than double the spread of data on a discordia obtained from the bulk sample, thereby yielding better-resolved concordia intercepts. However, isotopic ratios and morphologic characteristics indicate that the Pb/U systematics are complicated by inherited radiogenic lead. Although the data array cannot unequivocally be explained by the armoring process, the proposed methodology has succeeded in identifying groups of zircon with different isotopic characteristics. As such, this technique can be used to decipher complex geologic/isotopic histories and may be a useful addition to routine zircon geochronology.