The Original Organism Assemblages and Kerogen Carbon Isotopic Compositions of the Early Paleozoic Source Rocks in the Tarim Basin, China

Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.

Newly developed evidence for the original Tethysan island-arc volcanic rocks in the southern segment of the South Lancangjiang Belt

This paper re-describes the characteristics of pre-Ordovician (Pt3) metamorphic volcanic rocks in the Huimin-Manlai region of Yunnan Province from the aspects of petrographic characteristics, rock assemblage, petrochemistry, REE, trace elements, lead isotopes and geotectonic setting. The metamorphic volcanic rocks maintain blasto-intergranular and blasto-andesitic textures; the volcanic rocks are characterized by a basalt-andesite-dacite assemblage; the volcanic rocks are basic-intermediate-intermediate-acid in chemical composition, belonging to semi-alkaline rocks, with calc-alkaline series and tholeiite series coexisting, and they are characterized by low TiO2 contents; their REE distribution patterns are of the LREE-enrichment right-inclined type; the volcanic rocks are enriched in large cation elements and commonly enriched in Th and partly depleted in Ti, Cr and P, belonging to the Gondwana type as viewed from their Pb isotopic composition; petrochemically the data points fall mostly within the field of island-arc volcanic rocks. All these characteristics provided new evidence for the existence of original Tethysan island-arc volcanic rocks in the region studied.

Accounting for mineralogical composition and origin of soils and sedimentary rocks in thermal property predictions

A methodology for calculating the thermal conductivity of soils and rocks is developed which takes into account their origin and mineralogical composition.This method utilizes three approaches.One is founded on the structural modeling of contact heat interaction between particles and fills and estimates the statistical probability distribution of the particles in the volume of the medium.The second approach analyses perturbation to the temperature field of the matrix medium by ellipsoidal inclusions.The third approach is to find the mean thermal conductivity of the solid skeleton in the universal model at different composition of rock-forming minerals.

Origin and geochemistry of Pan-African granitoid rocks in the Gabal Um Shomer area,Southwestern Sinai,Egypt

Geological, petrological and geochemical studies indicated that there are two distinct types of granitoid rocks: older quartz diorites to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a meta-aluminous chemistry and a calc-alkaline character, with high MgO, Fe2O3, TiO2, CaO, P2O5, Sr and low SiO2, K2O, and Rb. Their major and trace elements data, together with low 87Sr/ 86Sr ratios (0.7029±0.0008) are indicative of I-type affinities. The second- and third-phase granitoids range from calc-alkaline to alkaline, respectively. The second-phase granitoids have a peraluminous chemistry and high Sr, Ba, CaO, MgO, Al2O3 and Ti2O and low SiO2, K2O, Nb, Y and Rb relative to the third-phase granitoids. The corundum normative nature and field observations suggested that it was formed by partial melting of the lower crust. The third-phase granitoids are alkaline in nature and characterized by higher SiO2, Rb, Y, Nb and lower MgO, Sr and Ba values than the younger granitoids (phase Ⅱ). They are A-type granitoids which were generated from below or within the existing continental crust.

Zircon U-Pb age, Lu-Hf Isotopic Characteristics and Origin of the Banshanping Granitoid Rocks in East Qinling Orogenic Belt

The Banshanping granitoid rocks distribute in the east of the North Qinling orogenic belt.It is a diorite-quartz diorite-granodiorite-granite series,spreading in a NW-SE direction,and intrudes into the Erlangping Group.The SiO2 content ranges from 57.04% to 76.56%,Na2O from 2.05% to 4.65%,K2O from 0.84% to 3.40%.Major element characteristics indicate that Banshanping granitoid rocks have properties of I type granotoids.SREE ranges from 36.51 ppm to 473.25 ppm,and LREE/ HREE ratios lie between 3.95 and 22.18.Negative Eu anomalies are not obvious in most samples,though there are obvious Nb,P and Ti positive anomalies.The zircon LA-ICP-MS ages of Banshangping granitoid rocks are 496.0±8.1 Ma-486.9±9.3 Ma.Hf isotope shows that 176Hf/177Hf ratios range from 0.282721 to 0.282876,εHf（t） values from 8.5 to 14,all positive,and corresponding modal ages （TDM2） range from 559 Ma to 908 Ma.Based on Hf isotope characteristics and existing SmNd and Rb-Sr isotope data,we consider that the Banshanping granitoid rocks originate from mantlederived material,i.e.the igneous rocks that formed in Neoproterozoic,and there may be a certain amount of crust-derived material during the formation of Banshanping granitoid rocks.

基于Origin的深部开采条件下地表移动预测研究

随着我国煤炭资源逐渐转向深部开采的发展趋势,开采沉陷带来了深部岩体变形问题和地表沉陷预测等技术难题.为了能更好地预测地表沉陷与深部岩石力学性质变化的关系,采用Origin曲线拟合函数中的非线性最小平方拟合来获得预测函数概率积分法参数,然后利用拟合出来的参数去分析和探讨深部开采地表沉陷规律,同时回归分析了所选预测函数模型及其效果.

黄金矿山深部开采井下热源分析

为量化黄金矿山深部开采过程中释放的热量,进而给出热害治理建议,分析了矿区原岩温度随深度的变化并对爆破、围岩、设备等热源散热量进行了计算。研究结果表明:矿区地温梯度约为1.7℃/100 m,进入-752 m中段生产时,原岩温度将达到34.3℃;深部开采过程中,夏季主要散热源为机械设备(电能)及空气压缩散热,分别占比38.18%及26.56%,冬季主要散热源为围岩散热及机械设备,分别占比38.74%及24.81%;深部开采通风量为67.9 m^(3)/s时,可保证深部开采过程中整体环境适宜性,当局部出现高温时,可以针对性采用加大通风进行降温。

云南澜沧地区澜沧岩群变质岩石类型特征与原岩恢复

云南澜沧地区澜沧岩群出露于昌宁-孟连结合带西部,划分为曼来岩组片岩,原岩为泥岩、粉砂质泥质岩、泥质粉砂岩类;惠民岩组钠长千枚岩,原岩为流纹岩;南坑河岩组变质石英砂岩,原岩为石英砂岩。为一套含火山陆源碎屑沉积,其沉积环境为被动陆缘。澜沧岩群变质带经历了三期变形变质作用,早期为加里东期,主变质时期为华力西期,后期局部叠加印支期动力变质作用。

内蒙古科右前旗树木沟地区大石寨组变质岩地球化学特征及原岩恢复

兴蒙造山带的大兴安岭地区,前人对火山岩成因和地球动力学演化机制研究较多,而大兴安岭中南段科右前旗的一带有关变质岩的研究还相对薄弱。本文通过对树木沟地区大石寨组变质岩进行地球化学分析及年代学研究,认为大石寨组变质岩地质年代为早二叠世,岩性组合为浅变质的中酸性火山碎屑岩夹砂岩,变质相为低绿片岩相;原岩主要为中性、中酸性晶屑凝灰岩,同时有少量沉积岩泥岩、砂岩,且原岩含有较多的石英及碳酸盐成分。

准噶尔盆地玛湖凹陷二叠系风城组白云质岩储集层白云石成因

针对准噶尔盆地玛湖凹陷二叠系风城组白云质岩储集层中自生白云石成因认识不清的问题,利用偏光、荧光薄片鉴定,扫描电镜分析,电子探针分析,碳、氧、锶同位素组成分析等技术,对玛湖凹陷风城组白云质岩中白云石赋存特征及成因演化进行深入研究。研究表明:(1)白云石发育准同生—浅埋藏期、中埋藏期和中—深埋藏期3期,主要形成于中二叠世早期的准同生—浅埋藏环境,其次是中二叠世中期的中埋藏环境。(2)白云石化流体为碱湖沉积背景下的高盐度咸水,准同生—浅埋藏期Mg2+主要由碱湖流体、火山玻璃脱玻化供给,中埋藏期Mg2+主要来自于黏土矿物转化、火山玻璃脱玻化以及长石等铝硅酸盐的溶蚀。(3)白云石生长过程中由早到晚Mg、Mn、Fe、Sr、Si等元素有规律的变化,主要与碱湖流体以及埋藏过程中风城组火山物质脱玻化、成岩蚀变的影响程度不同有关。(4)在碱湖微生物诱导作用下,准同生期泥晶—微晶白云石通过原生沉淀以及交代文石、高镁方解石等形成;浅埋藏期粉晶白云石主要由泥晶—微晶白云石的持续生长以及方解石、凝灰质等交代形成;中埋藏期白云石以粉晶、细晶为主,主要由白云石化流体对火山物质的交代形成。研究结果对玛湖凹陷及其他类似含油气区域白云石质致密储集层形成机理、发育规律的研究有一定借鉴意义。

Resources of Kaolinite Rocks in China Coal Measures

The proved reserve of kaolinite rocks in China coal measures is about 1.673 billion tons. The types of kaolinite rocks contain tonstein, flintclay and soft kaolin. Their origin modes include alteration of volcanic ash, terrigenous clay deposit and weathering of coal and adjacent rocks. The organic matter and organic acid play an important role in the formation of kaolinite rocks of coal measures. The difference in properties between kaolinite rock and traditional kaolin requires different processing technologies.

Geochronology and Genetic Model for Early Cretaceous Volcanic Rocks from the Southern Qiangtang Terrane,Northern Tibet,China: Constraints from U-Pb Zircon Dating, Whole-Rock Geochemical and Sr-Nd Isotopic Data

Post-collisional volcanic rocks of Mesozoic age occur in the regions adjacent to Gerze, part of the southern Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and wholerock Sr-Nd isotopic analyses were performed on the volcanic rocks to better characterize their emplacement age and models for their origin. Laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS) U-Pb zircon analyses yielded consistent ages ranging from 123.1±0.94 Ma to 124.5±0.89 Ma for six volcanic rocks from the study area. The intermediate volcanic rocks belong to the alkaline and sub-alkaline magma series in terms of K2 O+Na2 O contents(5.9%–9.0%), and to the shoshonitic and calc-alkaline series on the basis of their high K2 O contents(1.4%–3.3%). The Gerze volcanic rocks are characterized by the enrichment of light rare earth elements [(La/Yb)N=34.9–49.5] and large–ion lithophile elements(e.g., Rb, Ba, Th, U, K, Pb, and Sr), slightly negative Eu anomalies(Eu/Eu*=0.19–0.24), and negative anomalies in high field strength elements(e.g., Nb, Ta, Hf and Ti), relative to primitive mantle. The samples show slightly elevated(87 Sr/86 Sr)i values that range from 0.7049 to 0.7057, and low εNd(t) values from-0.89 to-2.89. These results suggest that the volcanic rocks studied derived from a compositionally heterogeneous mantle source and that their parent magmas were basaltic. The more mafic, parental magmas to the Gerze volcanic rocks likely underwent fractional crystallization of clinopyroxene, hornblende, biotite, and potassium feldspar, during ascent, with little to no crustal contamination, prior to their eruption/emplacement. While these volcanic rocks exhibit geochemical signatures typical of magmas formed in a destructive plate-margin setting, it is plausible that their mantle source might also have acquired such characteristics in an earlier episode of subduction.

Origin of Natural Gas in Kekeya Field, Tarim Basin, China

This paper is mainly concentrated on the geochemical characteristics and origin of gas of Kekeya field in the Tarim basin, NW China. This study shows that Permian mudstone is the main source rock of oil and gas. Based on the carbon isotopes of C 1-C 4, the carbon isotope of gas in Kekeya field is a little heavier than that in the typical marine-derived gas. The relationship between carbon isotopes of methane and ethane is coincident with Faber equation of gas derived from organic matter Ⅰ/Ⅱ. The majority of gas maturity is estimated, based on the formula, at 1.8 %-2.2 % besides K2 and K18 wells. In addition, the gas derived from 0.9 %-1.2 % R o source rocks may also be mixture. 40Ar/ 36Ar and 3He/ 4He ratios from the gas samples also support the mixing process. Moreover, the gas in this region is mainly generated from more mature source rocks although the low mature gas exists.

Discovery and Significance of High CH_4 Primary Fluid Inclusions in Reservoir Volcanic Rocks of the Songliao Basin,NE China

Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysis, we found that： （1） up to 82 mole% methane exists in the primary inclusions hosted in the reservoir volcanic rocks; （2） high CH4 inclusions recognized in the volcanic rocks correspond to CH4-bcaring CO2 reservoirs that are rich in helium and with a high ^3He/^4He ratio and which show reversed order of 813C in alkane; （3） in gas reservoirs of such abiotic methane （〉80%） and a mix of CH4 and CO2, the enclosed content of CH4 in the volcanic inclusions is usually below 42 mole%, and the reversed order of δ^13C in alkane is sometimes irregular in the corresponding gas pools; （4） a glassy inclusion with a homogeneous temperature over 900℃ also contains a small portion of CH4 although predominantly CO2. This affinity between gas pool and content of inclusion in the same volcanic reservoirs demonstrates that magma-originated gases, both CH4 and CO2, have contributed significantly to the corresponding gas pools and that the assumed hydrocarbon budget of the bulk earth might be much larger than conventionally supposed.

塔里木盆地顺托果勒地区奥陶系碳酸盐岩超压差异分布研究

随着塔里木盆地深层勘探领域的不断突破,顺托果勒地区超深层碳酸盐岩层系发现了一系列与走滑断裂有关的异常高压油气藏,但其超压成因和分布规律却少有讨论。相较于伸展盆地与挤压型前陆盆地体系,克拉通内走滑断裂与地层压力关系的研究相对较少,同时碳酸盐岩储层强烈的非均质性也进一步加剧了超压分布的复杂性。本次研究根据钻井测试与生产动态资料,分析了顺托果勒地区压力分布特征与超压储层特征;结合流体包裹体恢复的古压力、天然气地球化学特征与断裂活动期次讨论了顺托果勒地区不同二级构造单元间异常压力的成因机制差异。结果表明,顺北缓坡和顺托低凸起地层超压为天然气充注与构造增压作用产生,而顺南缓坡地层超压主要受原油裂解生气影响。天然气的生成与断裂活动特征决定了顺南地区整体超压、顺北与顺托地区局部超压的分布格局,走滑断控储层的发育模式使得顺托果勒地区中下奥陶统储层压力系统呈现分割状发育特征。

Methane-rich fluid inclusions and their hosting volcanic reservoir rocks of the Songliao Basin, NE China

Methane-rich fluids were recognized to be hosted in the reservoir volcanic rocks as primary inclusions. Samples were collected from core-drillings of volcanic gas reservoirs with reversed δ13C of alkane in the Xujiaweizi depression of the Songliao Basin. The volcanic rocks are rhyolite dominant being enriched in the more incompatible elements like Cs, Rb, Ba, Th, U and Th with relative high LREE, depleted HREE and negative anomalies of Ti and Nb, suggesting a melt involving both in mantle source and crustal assimilation. Primary fluids hosted in the volcanic rocks should have the same provenance with the magma. The authors concluded that the enclosed CH4 in the volcanics are mantle/magma-derived alkane and the reversed δ13C of alkane in the corresponding gas reservoirs is partly resulted from mixture between biogenic and abiogenic gases.

准噶尔盆地石树沟凹陷二叠系平地泉组烃源岩地球化学特征及形成条件

二叠系平地泉组为准噶尔盆地东部地区石树沟凹陷的主要烃源岩层。选取石树沟凹陷石树1和石树4井30个岩心样品,采用总有机碳质量分数、岩石热解、有机质岩石学和饱和烃气相色谱—质谱等实验,分析平地泉组一段(平一段)和二段(平二段)烃源岩地球化学特征、生烃潜力、沉积环境和有机母质来源,揭示优质烃源岩的形成条件。结果表明:石树沟凹陷二叠系平地泉组烃源岩主要分布于平地泉组一段和平地泉组二段,其中平一段烃源岩有机质丰度为中等—较高,有机质类型为Ⅱ1和Ⅱ2型,沉积于半咸水—咸水湖相环境。平二段烃源岩有机质丰度很高,有机质类型为Ⅰ和Ⅱ1型,沉积于微咸水—半咸水湖相环境,有机母质主要来源于湖相低等水生生物,且蓝藻、硅藻等低等水生生物输入贡献较大,与平一段相比,平二段烃源岩中其他藻类等水生生物输入贡献相对增大。平一和平二段烃源岩的沉积环境和生物来源差异较大,采用Pr/nC_(17)、Ph/nC_(18)、Ga/C_(30)藿烷及C_(27)/C_(29)规则甾烷可以较好地区分两套烃源岩。该结果为研究区油源对比及油气勘探开发提供地球化学依据。

Geology and Geochemistry of Reworking Gold Deposits in Intrusive Rocks of China-I.Features of the Intrusive Rocks

Most gold deposits in intrusive rocks were formed as a result of reworking processes.The intrusive rocks containing gold deposits and consisting of ultramafic-mafic, intermediate-acid and alkaline rocks of the Archean, Proterozoic, Caledonian, Hercynian and Yenshanian periods occur in cratons, activated zones of cratons and fold belts. Among them, ultramafic-mafic rocks, diorite, alkaline rocks, and anorthosite are products of remelting in the mantle or mantle-crust or mantle with crustal contamination. However, auriferous intermediate-acid rocks are products of metasomatic-remelting in auriferous volcanic rocks or auriferous volcano-sedimentary rocks in the deep crust.

湖相细粒沉积岩中晶粒方解石成因及其对火山-热液活动的指示——以吉木萨尔凹陷二叠系芦草沟组为例

以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组细粒沉积岩中晶粒方解石为研究对象,综合运用岩心观察、薄片观察、阴极发光分析、流体包裹体测试、扫描电镜、同位素组成分析等手段,对湖相细粒沉积岩中自生矿物的成因开展研究。结果表明:晶粒方解石呈层状分布于沉凝灰岩发育层段或沉凝灰岩与泥晶白云岩过渡层段的细粒沉积物中,方解石具有明显的阴极发光环带,可分为3期:Ⅰ期方解石不发光,含有较高的Sr元素,包裹体中包含羰基硫成分,均一温度超过170℃,由火山-热液喷流物质沉积形成;Ⅱ期方解石呈亮黄色光,含有较高的Fe、Mn、Mg元素,轻稀土元素富集,包裹体均一温度高,为热液喷流的钙质环边重结晶形成;Ⅲ期方解石呈暗橙色发光的环带,含有较高的Mg、P、V等元素,稀土元素无明显分异,包裹体均一温度低,为埋藏过程中成岩转化形成。晶粒方解石在垂向上规律性出现,并且其形成温度由颗粒中心向边缘降低,为芦草沟组沉积时期的火山-热液活动提供了直接证据。沉积期火山-热液活动有利于芦草沟组细粒沉积岩中的有机质富集,对优质烃源岩发育有正面效应,并且火山-热液喷流物质在演化过程中易形成晶间孔缝,为页岩油自生自储创造了条件。

闭坑铅锌矿区地下水-矿坑水水化学特征及成因分析

矿山关闭后,水位迅速回弹升高,区域水动力场发生改变进而影响到水化学场的演变,并伴随着严重的区域水环境问题。为研究闭坑矿区水体水化学特征和成因,系统采集丰水期、枯水期背景点、地下水和矿井水样测定现场参数、δ^(18)O和δD值、主量离子等,综合利用多元统计分析、同位素示踪和水化学计量分析等分析方法开展不同水体的水化学特征及成因分析。结果表明,(1)δ^(18)O和δD组成说明研究区地下水和矿井水主要来源为大气降水,且受到了不同程度的蒸发影响;同一季节内背景点、地下水、矿井水同位素组成具有分区聚集性,丰水期同位素相对亏损,枯水期相对富集,表明不同水体水力联系密切;分层聚类分析和水化学同样揭示了不同含水层之间存在密切的水力联系。(2)研究区水化学具有较大差异。背景点、地下水、矿井水TDS取值范围分别为44.18—138.86、43.39—6917.6、3329.22—4174.20 mg·L^(−1),从淡水到咸水均有分布;pH取值范围分别为4.39—8.2、2.75—7.9、2.87—2.92,呈酸性、弱酸性、中性、弱碱性。水化学类型沿补—径—排路径发生系统性演化,背景点、地下水、矿井水水型依次为Ca-Mg-HCO_(3)型、Ca-SO_(4)型、Ca-SO_(4)型。(3)水岩作用是控制研究区水化学演化的主要因素。背景区地下水受制于硅酸盐的溶解,水岩作用较弱;矿区地下水水岩作用增强,受硫化物氧化和硅酸盐、碳酸盐岩的溶解的共同影响,形成中性或偏碱性地下水;矿井水主控水岩反应为硫化矿物的氧化溶解,形成典型低pH、高SO_(4)^(2−)的酸性矿山排水。矿山闭坑后水文地球化学特征及主控因素的研究对区域水环境重金属污染防控具有重要意义。