Elemental characteristics of lacustrine oil shale and its controlling factors of palaeo-sedimentary environment on oil yield: a case from Chang 7 oil layer of Triassic Yanchang Formation in southern Ordos Basin

As an important unconventional resource, oil shale has received widespread attention. The oil shale of the Chang 7 oil layer from Triassic Yanchang Formation in Ordos Basin represents the typical lacustrine oil shale in China. Based on analyzing trace elements and oil yield from boreholes samples, characteristics and paleo-sedimentary environments of oil shale and relationship between paleo-sedimentary environment and oil yield were studied. With favorable quality, oil yield of oil shale varies from 1.4% to 9.1%. Geochemical data indicate that the paleo-redox condition of oil shale’s reducing condition from analyses of V/Cr, V/(V + Ni), U/Th, δU, and authigenic uranium. Equivalent Boron, Sp, and Sr/Ba illustrate that paleosalinity of oil shale is dominated by fresh water. The paleoclimate of oil shale is warm and humid by calculating the chemical index of alteration and Sr/Cu. Fe/Ti and (Fe + Mn)/Ti all explain that there were hot water activities during the sedimentary period of oil shale. In terms of Zr/Rb, paleohydrodynamics of oil shale is weak. By means of Co abundance and U/Th, paleo-water-depth of oil shale is from 17.30 to 157.26 m, reflecting sedimentary environment which is mainly in semi deep–deep lake facies. Correlation analyses between oil yield and six paleoenvironmental factors show that the oil yield of oil shale is mainly controlled by paleo-redox conditions, paleoclimate, hot water activities, and depth of water. Paleosalinity and paleohydrodynamics have an inconspicuous influence on oil yield.     

Timing of mineralization at the Shihu gold deposit in the middle segment of the Taihang Mountain,China

The Shihu gold deposit, located in the middle-south section of the core of the Fuping mantle branch structure, is hosted in the Archean Fuping Group and adjacent to the quartz diorite porphyrite. The gold deposit is the only large gold deposit with reserves of more than 30 tons gold discovered in western Hebei Province so far. In order to constrain the timing of mineralization of this ore deposit, this paper focuses on the isotopic dating of zircon and pyrite. Zircons in gold-bearing quartz veins are magmatic in origin and no hydrothermal zircon has been found in such quartz veins, indicating that zircons were derived from the wall rocks. U–Pb ages of zircons fall mainly in the two domains: 2492 ± 82 and 136 ± 4 Ma, respectively, indicative of the contribution of the Fuping-Group TTG gneiss and Yanshanian igneous rocks, respectively. The Re–Os isotopic compositions of pyrites in the gold-bearing quartz veins yield an isochron age of 127 ± 31 Ma. Combined with other dating results, we suggest that the main metallogenic age of the Shihu gold deposit is 120–127 Ma.     

考虑方位漂移的水平井井眼轨道设计

目前,深层页岩气水平井在钻井过程中经常出现方位漂移的问题,方位漂移严重影响了水平井的井眼轨迹控制,进而影响水平井的准确中靶。在现场施工中,通常根据施工区以前的钻井经验,在进行定向造斜时,先估计出一个“方位超前角”,这种现场的做法有着很大的不确定性,并且可能出现较大误差。本文提出了考虑方位漂移的水平井井眼轨道优化设计的方法,解决了仅凭现场经验给出的“超前角”不准确的问题。考虑方位漂移的水平井井眼轨道优化设计按照井段划分,将地层因素与井身剖面结合起来求取井段的平均方位漂移率。根据该方法研制开发了考虑方位漂移的水平井井眼轨道优化设计软件,并通过举例进行了验证,证明了方法是可行的。     

地质导向技术在L型煤层气水平井 T-P05井中的应用

通过分析山西L型煤层气水平井的技术难点,着重建立造斜着陆与水平段导向两大导向模型,形成了以标志层划分与对比、地层倾角推算、地质建模和实时轨迹控制四个方面为主的L型煤层气水平井地质导向技术流程,该技术在T-P05井的成功应用,不仅丰富了煤层气水平井地质导向技术的内容与方法,更进一步验证了该技术在现场具有较强的可操作性和良好的应用前景,值得大力推广。     

贵州松桃高地特大型富锰矿床主要地质特征

位于贵州铜仁松桃国家锰矿整装勘查区内的高地富锰矿床,(332)+(333)类碳酸锰富锰矿石资源量达7 166. 84万吨,锰平均品位25. 75%,矿体平均厚度4. 52 m,富锰矿体赋存于总资源量达1. 61亿吨的高地超大型锰矿床之中,由一个单一的富锰矿体构成,是我国新发现的首个特大型富锰矿床,富锰矿资源量相当于我国富锰矿资源量总和的2倍。成因类型属古天然气渗漏沉积型锰矿床,富锰矿产于古天然气渗漏沉积成矿系统中心相区。高地富锰矿床地处独特的"新月形"南华纪早期李家湾-高地-道坨(Ⅳ级)地堑盆地中心,菱锰矿体中均出现以块状构造夹被沥青充填的气泡状富菱锰矿石。地表燕山期北北东向的断裂构造十分发育,但主要为上陡下缓犁式正断层,未触及高地深部隐伏巨型锰矿体,以致富锰矿体保存亦十分完整,易于开发利用。     

Flooding a landscape: impact of Holocene transgression on coastal sedimentology and underwater archaeology in Kiladha Bay (Greece)

Franchthi Cave, bordering Kiladha Bay, in Greece, is a key archaeological site, due to its long occupation time, from?~?40,000 to?~?5000 year BP. To date, no clear evidence of Neolithic human dwellings in the cave was found, supporting the assumption that Neolithic people may have built a village where there is now Kiladha Bay. During the Neolithic period/Early Holocene, wide areas of the bay were indeed emerged above sea level. Bathymetric and seismic data identified a terrace incised by a valley in?~?1 to 2 m sediment depth. Eight sediment cores, up to 6.3-m-long, were retrieved and analysed using petrophysical, sedimentological, geochemical, and chronostratigraphic methods. The longest core extends into the exposure surface, consisting of a layer of carbonate rubble in a finer matrix, representing weathering processes. Dated organic remains place this unit at?~?8500 cal year BP. It is overlain by stiff silty mud representing an estuarine environment. This mud is capped by reduced sediments with roots marking an exposure surface. A shell-layer, dated to?~?6300 cal year BP, overlies this terrestrial sequence, reflecting the marine transgression. This layer occurs at 10.8 mbsl, 7.7 m deeper than the global sea level at that time, suggesting tectonic subsidence in the area. It is overlain by finer-grained marine carbonate-rich sediments. The top of the core shows traces of eutrophication, pebbles and marine shells, all likely a result of modern anthropogenic processes. These results are interpreted in the context of human occupation: the exposed surface contains pottery sherds, one dating to the Early to Middle Neolithic period, indicating that Neolithic people were present in this dynamic landscape interacting with a migrating coastline. Even if the artefacts are isolated, future investigations of the submerged landscape off Franchthi Cave might lead to the discovery of a Neolithic village, which eventually became buried under marine sediments.     

利用GPR天线-目标极化的瞬时属性分析方法探测LNAPL污染土壤

轻非水相流体(LNAPL)泄漏后会对土壤和地下水造成严重污染,为了准确探测出LNAPL泄漏范围,本文将GPR天线-目标极化的瞬时属性分析方法应用于轻非水相流体污染土壤探测的研究中。采用注入柴油的石英砂砂箱在实验室建立污染土壤模型,利用探地雷达对该污染土壤分别进行天线方位为0°、90°的测量。LNAPL土壤污染物形状、大小、结构并不规则,因此可以通过0°和90°方位天线测量来分析天线-目标极化特征,了解目标物的走向、形状等地下介质信息。通过对预处理后的包含天线-目标极化特征的信息进行瞬时属性分析,LNAPL污染范围可以被清晰地识别,提高了GPR探测能力。     

滇东南富宁地区基性侵入岩及喷出岩时代

在滇东南富宁地区基性侵入岩、喷出岩较发育,前人将其划分为"半瓦型"侵入岩、"安定型"侵入岩和"龙康型"喷出岩3类,3类岩石普遍缺乏可靠的同位素年代学资料。在对富宁地区基性侵入岩、喷出岩进行区域地质调查的基础上,应用LAICP-MS技术对其进行锆石U-Pb测年,在半瓦型侵入岩和安定型侵入岩中分别获得了254.0±2.0Ma和244.2±4.4Ma的加权平均年龄,在龙康型喷出岩中获得251.9±3.0Ma和255.92±0.72Ma加权平均年龄。结合野外调查和综合研究,将富宁地区"安定型"侵入岩的时代界定于中三叠世,将"半瓦型"侵入岩和"龙康型"喷出岩的时代界定于晚二叠世。