大河煤田钻孔复杂因素分析及施工技术对策

为了解决大河煤田复杂地层钻进施工难的问题,对钻探施工中遇到的复杂地层情况进行分析,提出了采用技术套管、堵漏材料和不同类型的优质泥浆进行护孔堵漏钻进,较顺利地通过了复杂地层,达到了终孔设计要求,取得了良好的经济效益。     

Simultaneous Determination of Fluorine,Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis,Ion Chromatography and Inductively Coupled Plasma‐Mass Spectrometry

Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO‐2, GS‐N, JG‐1, JR‐1, JB‐1b, JB‐2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma‐mass spectrometry for Br and I. The detection limits in solutions were 100 μg l^?1 for both F and Cl and 10 ng l^?1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg^?1 for F and Cl and 2 μg kg^?1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg^?1 for F and Cl, 100 μg kg^?1 for Br and 25 μg kg^?1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites – the powders of which were heterogeneous in halogens at the 500 mg level.     

Determination of Fluorine and Chlorine by Pyrohydrolysis and Ion Chromatography: Comparison with Alkaline Fusion Digestion and Ion Chromatography

A method to determine F and Cl in silicate materials by employing pyrohydrolysis and ion chromatography (IC) is described. Pyrohydrolysis involved mixing a pulverised sample (∼ 40 mg) with V₂O₅ (∼ 160 mg) and heating to 1100 °C under a wet oxygen flow in a quartz tube. Recovery yields of F and Cl were ∼ 97% using a NaF + NaCl standard solution. Detection limits of the pyrohydrolysis-IC method for silicate samples were 0.36 and 0.69 μg g^-1 for F and Cl, respectively. Fluorine and Cl concentrations were determined in the reference materials JB-2, JB-3 and JA-1 from the GSJ; BCR-2, BHVO-1, BHVO-2, AGV-1 and AGV-2 from the USGS; and NIST SRM 610, 612 and 614 glasses. Precisions (RSD) for determinations of F were 1–13% (except NIST SRM 614) and 2–19% for Cl, and were dependent on the concentration and blank correction. Most results obtained in this study were in good agreement with those of previous studies. In comparison, the Na₂CO₃ + ZnO fusion method at 900 °C showed that the yields of F and Cl by alkaline fusion systematically decreased with fusion duration time. The yields were 84% and 83% for JB-3, inferring that F and Cl were lost in this alkaline fusion.     

Rare Earth and High Field‐Strength Elements in the Multani Mitti Clay: A Study Using INAA

Instrumental neutron activation analysis was used to determine nine rare earth elements (REE), Sc and five high field‐strength elements (HFSE) in the Multani Mitti (MM) clay. Chondrite‐normalised rare earth element patterns for the MM clay compared with those for the Post‐Archaean Australian Shale (PAAS), Upper Continental Crust (UCC) and North American Shale Composite (NASC) showed enrichment of light REEs and depletion of heavy REEs with a slight negative Eu anomaly. The Multani Mitti clay showed close resemblance to PAAS and NASC in its average REE and HFSE contents. Positive correlations between La/Ce, La/Sm, La/Yb, Zr/Hf, Th/U and Th/Ta ratios predict enrichment of LREEs, Zr and Th and depletion of HREEs. A parent source of felsic origin for the MM clay is also endorsed through the high La/Th and low Th/Sc ratios observed.     

A geoarchaeological approach to the evolution of the town and port of Dover: Prehistoric to Saxon periods

Dover is located at the mouth of a narrow valley that forms the only significant break in almost 20 km of chalk cliffs along the Kentish Channel coast. This, together with the close proximity of the Continent, has ensured the site's standing as a port since pre-Roman times. However, little is known of the sequence of events associated with the transformation of the area since the later prehistoric period, and in particular the evolution of the harbour which has had at least four different locations. Work to regenerate central Dover has however provided opportunities to address these issues and we report here on geological evidence for harbour development and coastal change from the middle Holocene period to the present day.Foraminifera and ostracods recovered from boreholes and excavations in the town centre allow patterns of sedimentation to be identified and linked to archaeological finds such as the Dover Bronze Age Boat and Roman harbour installations. Radiocarbon dating, and archaeological spot-dating provides a chronological framework for these changes. In particular the later Prehistoric environments and their transformation to estuarine environments by the time of Roman activity in the area are examined (including the role of sea level change and coastal erosion). The history of sedimentation within the Roman harbour and the role played by human activity in accelerating sedimentation in the old valley mouth is also considered. Finally dune formation across former estuarine habitats is documented in the Anglo-Saxon period creating the topographic template on which the modern town is based.     

黄河下游地区堌堆遗址时空分布特征及其与黄河洪水关系

通过对考古资料和古文献的查询、总结,阐释了黄河下游地区堌堆遗址的形成及其时空分布特征,利用地理学和统计学的方法,分析了该地区堌堆遗址分布与黄河洪水之间的关系。研究表明,堌堆遗址时间分布为大汶口文化、龙山文化、岳石文化、商周与汉时期,且主要分布在龙山文化时期,可能反映了古人类向黄河下游迁移及洪水相对频发的情势;汉代以后由于国家和黄河两岸居民抵御黄河洪水的策略转为筑堤,且此后一段时期黄河长期安流,致使堌堆被逐渐废弃。堌堆遗址空间分布为鲁西南,豫东北地区,位于历史时期黄河频繁改道与泛滥的重点区域,这些地区地势较低,容易发生洪水泛滥事件。研究认为黄河洪水是影响堌堆遗址分布的主要因素,洪水的出现迫使人类避往高处,而生活在平原地区的居民主要采取加高居住地的策略避洪,从而形成了堌堆—今日的堌堆遗址。     

Potential Orthopyroxene,Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination

Over 1400 electron probe and 700 ion probe microanalyses were performed on eleven mineral separates to evaluate their potential as reference materials for in situ Li isotopic determination. Our results suggest the homogenous distributions of major elements, Li and its isotopes for each sample. Hence, these samples are suitable to be used as reference materials for in situ measurements of Li abundance and Li isotopes by secondary ion mass spectrometry (SIMS) or laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). These samples have the advantage of mitigating probable matrix effects during calibration owing to the wide range of compositions. The effect of composition on the δ⁷Li of olivine measured by SIMS is a linear function of composition, with δ⁷Li increasing by 1.0‰ for each mole per cent decrease in forsterite component.     

Ion Implants as Matrix‐Appropriate Calibrators for Geochemical Ion Probe Analyses

Ion microprobe elemental and isotopic determinations can be precise but difficult to quantify. Error is introduced when the reference material and the sample to be analysed have different compositions. Mitigation of such ‘matrix effects’ is possible using ion implants. If a compositionally homogeneous reference material is available which is ‘matrix‐appropriate’ (i.e., close in major element composition to the sample to be analysed, but having an unknown concentration of the element, E, to be determined) then ion implantation can be used to introduce a known amount of an E isotope, calibrating the E concentration and producing a matrix‐appropriate calibrator. Nominal implant fluences (ions cm^?2) are inaccurate by amounts up to approximately 30%. However, ion implantation gives uniform fluences over large areas; thus, it is possible to ‘co‐implant’ an additional reference material of any bulk composition having known amounts of E, independently calibrating the implant fluence. Isotope ratio measurement standards can be produced by implanting two different isotopes, but permil level precision requires postimplant calibration of the implant isotopic ratio. Examples discussed include (a) standardising Li in melilite; (b) calibrating a ²⁵Mg implant fluence using NIST SRM 617 glass and (c) using Si co‐implanted with ²⁵Mg alongside NIST SRM 617 to produce a calibrated measurement of Mg in Si.     

The impact of spatial scale on local Moran's I clustering of annual fishing effort for Dosidicus gigas offshore Peru

The spatial scale(?shing grid) of ?sheries research af fects the observed spatial patterns of?sheries resources such as catch-per-unit-ef fort(CPUE) and ?shing ef fort. We examined the scale impact of high value(HH) clusters of the annual ?shing ef fort for Dosidicus gigas of fshore Peru from 2009 to 2012.For a multi-scale analysis, the original commercial ?shery data were tessellated to twelve spatial scales from 6′ to 72′ with an interval of 6′. Under these spatial scales, D. gigas clusters were identi?ed using the Anselin Local Moran's I. Statistics including the number of points, mean CPUE, standard deviation(SD),skewness, kurtosis, area and centroid were calculated for these HH clusters. We found that the z-score of global Moran's I and the number of points for HH clusters follow a power law scaling relationship from2009 to 2012. The mean ef fort and its SD also follow a power law scaling relationship from 2009 to 2012.The skewness follows a linear scaling relationship in 2010 and 2011 but ?uctuates with spatial scale in2009 and 2012; kurtosis follows a logarithmic scale relationship in 2009, 2011 and 2012 but a linear scale relationship in 2010. Cluster area follows a power law scaling relationship in 2010 and 2012, a linear scaling relationship in 2009, and a quadratic scaling relationship in 2011. Based on the peaks of Moran's I indices and the multi-scale analysis, we conclude that the optimum scales are 12′ in 2009 ? 2011 and 6′ in 2012, while the coarsest allowable scales are 48′ in 2009, 2010 and 2012, and 60′ in 2011. Our research provides the best spatial scales for conducting spatial analysis of this pelagic species, and provides a better understanding of scaling behavior for the ?shing ef fort of D. gigas in the of fshore Peruvian waters.     

Boron Isotope Analysis of Silicate Glass with Very Low Boron Concentrations by Secondary Ion Mass Spectrometry

We present an improved method for the determination of the boron isotopic composition of volcanic glasses with boron concentrations of as low as 0.4–2.5 μg g^?1, as is typical for mid‐ocean ridge basalt glasses. The analyses were completed by secondary ion mass spectrometry using a Cameca 1280 large‐radius ion microprobe. Transmission and stability of the instrument and analytical protocol were optimised, which led to an improvement of precision and reduction in surface contamination and analysis time compared with earlier studies. Accuracy, reproducibility (0.4–2.3‰, 2 RSD), measurement repeatability (2 RSE = 2.5–4.0‰ for a single spot with [B] = 1 μg g^?1), matrix effects (? 0.5‰ among komatiitic, dacitic and rhyolitic glass), machine drift (no internal drift; long‐term drift: ~ 0.1‰ hr^?1), contamination (~ 3–8 ng g^?1) and machine background (0.093 s^?1) were quantified and their influence on samples with low B concentrations was determined. The newly developed set‐up was capable of determining the B isotopic composition of basaltic glass with 1 μg g^?1 B with a precision and accuracy of ± 1.5‰ (2 RSE) by completing 4–5 consecutive spot analyses with a spatial resolution of 30 μm × 30 μm. Samples with slightly higher concentrations (≥ 2.5 μg g^?1) could be analysed with a precision of better than ± 2‰ (internal 2 RSE) with a single spot analysis, which took 32 min.