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1.
东准噶尔卡拉麦里蛇绿岩带南侧分布有大量的石炭纪侵入体,主要出露于五彩城、滴水泉一带及野马站地区。通过对卡拉麦里断裂以南侵入体岩石类型、锆石年代学、地球化学的综合分析,划分出早石炭世后碰撞I型花岗岩类及晚石炭世陆内双峰式侵入岩(碱长花岗岩+角闪辉长岩)。结合断裂以北黄羊山、老鸦泉岩体新近发表的数据及区域内火山岩的研究成果,对卡拉麦里地区石炭纪—二叠纪构造-岩浆演化过程给出了新认识,即卡拉麦里地区从后碰撞到陆内伸展的构造转换时间为早石炭世末期—晚石炭世早期,后碰撞阶段岩浆岩以钙碱性I型花岗岩、玄武安山岩、安山岩为特点,陆内伸展阶段以典型的双峰式岩浆岩(辉长岩+花岗岩、玄武岩+流纹岩)及A型花岗岩为特点,卡拉麦里地区具有正εNd值的花岗岩类来源于亏损地幔形成的年轻地壳的部分熔融。 相似文献
2.
西藏北部石炭纪冰川-海洋相地层的发现 总被引：3，自引：0，他引：3
<正> 1980年作者在西藏林周、申扎地区发现了石炭纪冰海相沉积地层。林宝玉在《地质论评》1981年第27卷第 4期曾作过报道。但该文称其为“与冰水有关的沉积”,时代属“中石炭世永珠群上组”。作者通过详细室内研究,认为该区冰海相地层的形成,不是“与冰水有关的沉积”,而是属冰川-海洋相(简称冰海相)复合成因的产物。同时申扎地区冰海相地层不但在中石炭世有广泛分布,在下石炭统、上石炭统也有发现。 相似文献
3.
塔里木盆地西北缘石炭系砂岩成岩作用研究 总被引：2，自引：0，他引：2
本文是在薄片研究基础上,并使用阴极发光显微镜、扫描电镜、X射线衍射分析以及氧碳同位素分析资料详细研究了塔里木盆地西北缘石炭系砂岩的机械压实,压溶.胶结等主要成岩作用.并应用镜质体反射率、孢粉颜色及伊利石开形指数的测定等方法推断石炭系砂岩所经历的最高成岩温度为120℃-200℃.并且根据成岩作用和成岩温度的研究,对砂岩所处的成岩阶段位置及其成岩历史和孔隙演化特点进行了分析. 相似文献
4.
Sixteen basic and intermediate composition igneous glacial erratics from Anglian (pre-423,000 years) deposits in Hertfordshire and Buckinghamshire, southern Britain, were selected for chemical and petrographic analysis in order to determine their original source outcrops. Major and trace element compositions suggest that seven samples (plus two uncertain) originated in the Lower Carboniferous volcanics of the Scottish Midland Valley (SMV), four came from the Upper Carboniferous quartz dolerite association which crops out in Scotland, northern England (Whin Sill) and extends to Norway, and one came from the northern England Cleveland Dyke. One sample of altered dolerite is ambiguous but has some similarity to the Old Red Sandstone (Devonian) age lavas of the SMV, and one meta-basalt sample may be from southwest Scotland or Scandinavia. These results identify specific outcrops which provided glacial erratics within currently accepted ice trails in the United Kingdom, and provide the first supporting evidence based on geochemistry, rather than petrography, for these ice movements. The distribution and provenance of glacial erratics are of importance in archaeological studies, because erratics provided a potential source of raw material for stone implement production. There is a marked geographical correlation between the distribution of prehistoric stone implements of quartz dolerite in the United Kingdom, and directions of ice movements from quartz dolerite outcrops within Britain. This correlation lends support to the hypothesis that prehistoric man made extensive use of glacial erratics for implement manufacture, as an alternative to quarrying at outcrops and subsequent long-distance trade. © 1999 John Wiley & Sons, Inc. 相似文献
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6.
本文主要描述了关岭生物群中一美丽盘江鱼龙标本（YIGM V30016）-Panjiansaurus epicharis Chen＆Cheng体内的胃融物。其组成物质为微晶含有机质胶磷质生物碎屑灰岩。其中生物碎屑主要为较小的鱼类骨碎片．其次含有少量的双壳类外壳，没有胃石。通过分析胃融物的成分，比较牙齿类型和身体特征等，认为盘江鱼龙主要以小型鱼类和双壳类为食，并不需胃石帮助消化食物。 相似文献
7.
LENA HÅKANSSON HELENA ALEXANDERSON CHRISTIAN HJORT PER MÖLLER JASON P. BRINER ALA ALDAHAN GÖRAN POSSNERT 《Boreas: An International Journal of Quaternary Research》2009,38(2):244-260
Previous work has presented contrasting views of the last glaciation on Jameson Land, central East Greenland, and still there is debate about whether the area was: (i) ice-free, (ii) covered with a local non-erosive ice cap(s), or (iii) overridden by the Greenland Ice Sheet during the Last Glacial Maximum (LGM). Here, we use cosmogenic exposure ages from erratics to reconcile these contrasting views. A total of 43 erratics resting on weathered sandstone and on sediment-covered surfaces were sampled from four areas on interior Jameson Land; they give 10 Be ages between 10.9 and 269.1 kyr. Eight erratics on weathered sandstone and till-covered surfaces cluster around ∼70 kyr, whereas 10 Be ages from erratics on glaciofluvial landforms are substantially younger and range between 10.9 and 47.2 kyr. Deflation is thought to be an important process on the sediment-covered surfaces and the youngest exposure ages are suggested to result from exhumation. The older (>70 kyr) samples have discordant 26 Al and 10 Be data and are interpreted to have been deposited by the Greenland Ice Sheet several glacial cycles ago. The younger exposure ages (≤70 kyr) are interpreted to represent deposition by the ice sheet during the Late Saalian and by an advance from the local Liverpool Land ice cap in the Early Weichselian. The exposure ages younger than Saalian are explained by periods of shielding by non-erosive ice during the Weichselian glaciation. Our work supports previous studies in that the Saalian Ice Sheet advance was the last to deposit thick sediment sequences and western erratics on interior Jameson Land. However, instead of Jameson Land being ice-free throughout the Weichselian, we document that local ice with limited erosion potential covered and shielded large areas for substantial periods of the last glacial cycle. 相似文献
8.
M. Qasim Jan M. Hassan Agheem Amanullah Laghari Suhail Anjum 《Journal of the Geological Society of India》2017,89(1):91-98
Kharsar hill is one of many granitic plutons comprising the Nagar Parkar igneous complex. The eastern part of the hill is occupied by grey-pink granite (earlier) and the western part by pink granite (later). They are composed of perthite, quartz, and plagioclase, with minor opaque oxide, biotite, titanite, local amphibole, and secondary chlorite, epidote, leucoxene/titanite. The pink granite is characterized by the presence of mafic clots. Both the granitoids are intruded by microgranite/aplite, and porphyritic mafic and rhyolite dykes, locally in swarms. These are abundant in a NE trending 200 m wide zone cutting the entire granite hill. The dykes may extend over 1 km in length and >10 m in thickness, but most are < 100 m in length. The felsic dykes are of several generations; some are associated with the two varieties of granite, others are contemporaneous with the rhyolite and mafic dykes. The mafic dykes can be grouped into two types one of which contains hornblende and the other augite as the principal mafic mineral. Major element analyses suggest that the granitic rocks are metaluminous. The Kharsar granites, like the others in Nagar Parkar, may be an extension of the Malani igneous suite of Rajasthan. The occurrence of bimodal mafic-felsic dykes and petrographic variation in the mafic dykes are briefly discussed. 相似文献
9.
准噶尔盆地天山山前油气前景展望 总被引：10，自引：1，他引：10
准噶尔盆地南缘经历了晚古生代类克拉通盆地演化阶段和中新生代前陆盆地演化阶段．自石炭纪后地层发育齐全、分布广、厚度大，构造方向以NWW和近EW向为主，大体发育3个逆冲断裂系统，剖面上多呈叠瓦状．该地区构造圈闭发育，并成排成带分布，具多套烃源岩，存在多套储盖组合，是准噶尔盆地主要增储上产地区之一． 相似文献
10.
我国铀矿床主要划分为四大类型,包括花岗岩型铀矿床、火山岩型铀矿床、砂岩型铀矿床和碳硅泥岩型铀矿床。花岗岩型铀矿约占我国已探明铀矿总资源储量的三分之一以上,是我国重要的铀矿化类型。地球化学勘探方法对花岗岩型铀矿床勘查具有良好的效果。根据全国铀矿资源潜力评价项目研究成果,在大量研究中国花岗岩型铀矿化水系沉积物地球化学异常特征基础上,总结了一套对花岗岩型铀矿化勘查稳定的、行之有效的指示元素及其组合,确定了花岗岩型铀矿化地球化学异常模式,并以实例说明典型花岗岩型铀矿化异常模式。水柰沉积物地球化学异常是进行铀矿产预测评价的有效手段,对铀矿资源的潜力评价发挥了重要作用。 相似文献
11.
A total of more than 40 tridactyl and didactyl tracks were preserved as natural casts on four fallen blocks of sandstone representing the Lower Cretaceous Jiaguan Formation of Gulin County in southeastern Sichuan Province, China. While several trackways can be distinctly followed, others are isolated imprints only. All have been flattened by overburden pressures. Tridactyl tracks are present with three size-classes being <10 cm, 10–20 cm and >20 cm in length. Morphologically they are similar to the ichnogenus Eubrontes, considering the relatively weak mesaxony. Eight of the tracks on one of the blocks are clearly didactyl and are here interpreted as representing large and medium sized dromaeosaurids. The largest track is about ∼30 cm long and comparable in size to the type of Dromaeopodus (∼28 cm), from the Lower Cretaceous of Shandong Province, which was the largest dromaeosaurid track previously reported. This report adds new data to the growing number of dromaeosaurid tracksites reports from China, and from the Jiaguan Formation, suggesting that this theropod group had a preference for fluvial paleoenvironments. 相似文献
12.
RUDOLPH R. STEA GEORGIA PE-PIPER 《Boreas: An International Journal of Quaternary Research》1999,28(2):308-325
Whole rock geochemistry has been determined for erratics from the surface Lawrencetown Till in two drumlins on the Atlantic coast of Nova Scotia. The geochemical data, particularly trace element composition, allow source rocks to be identified more precisely than by traditional petrographic microscopy. A drumlin near Lunenburg contains erratics of Neoproterozoic arc-related plutonic rocks and basalts that outcrop only in a small area near Parrsboro in the Cobequid Highlands. Some associated erratics of granite precisely match a small late Devonian pluton in the same area and other granites and rhyolite could also be derived from late Devonian rocks in the same area. The type section of the Lawrencetown Till contains different Neoproterozoic plutonic rocks of a type found in the eastern Cobequid Highlands, together with a distinctive late Devonian granite with sodic amphiboles that is restricted to a small area near the Debert River. Both these source areas indicate a southward flow of ice (Escuminac Phase) depositing the Lawrencetown Till, in contrast to earlier southeastward-flowing ice (Caledonia Phase) which deposited the Hartlen Till that forms the core of the drumlin. Drumlins in Nova Scotia are complex palimpsest landforms that were formed by till accretion, and evolved in surface form throughout multiple flow events. 相似文献
13.
Asfawossen Asrat 《Geoarchaeology》2002,17(7):649-663
Ethiopia is endowed with many rock‐hewn churches, with the largest group in central and eastern Tigrai. These churches can be divided into four zones: the Atsbi, Hawzen‐Ger'alta, Sinkata‐Adigrat, and Tembien, with more than 100 rock‐hewn churches of different ages, sizes, and histories. However, they have one thing in common: All are carved into sandstone. The Enticho, Adigrat, and Ambaradam sandstones (Permo‐Carboniferous, Triassic—Middle Jurassic, and Early Cretaceous, respectively) are extensively exposed in these areas and are characterized by thick and massive beds of coarse‐ to fine‐grained and well‐sorted successions. These sandstones are easily carved, yet compact enough to withstand pressure. Although limestone, basalt, and crystalline rocks are exposed in the same area, few rock‐hewn churches have been carved into them. The rock type is, therefore, the most important factor in the location of these rock‐hewn churches. © 2002 Wiley Periodicals, Inc. 相似文献
14.
雪峰古陆边缘石岩统为一套滨浅海碳酸盐岩和碎屑岩沉积。下部黄龙组为白云岩，灰岩和砾岩及少量硝岩互层，上部船山组为灰岩，白云质与砂岩及少量砂岩互层，船山组含Ｔｒｉｔｉｃｉｅｓ带和Ｐｓｅｎｄｏｓｃｈｗａｇｅｎｉｎａ带。整个上石炭统碎屑岩和碳酸盐岩交替出现，属海水浅的滨海陆脊滩相至局限台地相。 相似文献
15.
Failure of Layered Sandstone under Brazilian Test Conditions: Effect of Micro-Scale Parameters on Macro-Scale Behaviour 总被引：3，自引：2，他引：1
The experimental research in this paper focuses on the effect of micro-scale parameters on macro-scale behaviour of samples
tested under Brazilian test conditions for one particular layered sandstone, i.e. sandstone from Modave in the South of Belgium.
Five (visually) similar blocks are studied; however, they are different at micro-scale. Their differences on microscopic level
(such as grain size, mineral contents and number of layer boundaries) affect the failure process. Fracture length parallel
to the layers increases if more layer boundaries (e.g. per cm) are present and more weak minerals. The Brazilian tensile strength
of studied layered Modave sandstone is larger for larger quartz grains, while fracture length parallel to the layers is smaller.
Quartz grains in the studied layered sandstone are classified as fine sand. 相似文献
16.
HENRIETTE LINGE EILIV LARSEN KURT H. KJæR IGOR N. DEMIDOV EDWARD J. BROOK GRANT M. RAISBECK FRANCOISE YIOU 《Boreas: An International Journal of Quaternary Research》2006,35(3):576-586
Rock samples from the Kanin Peninsula and the Timan Ridge were analysed for in situ cosmogenic 10Be for exposure age dating purposes. Crystalline rocks were sampled at four sites on the Kanin Peninsula, either from bedrock outcrops or from glacial erratics, giving overall similar 10Be ages. Outcropping sandstone and crystalline erratics were available from three sites at the Timan Ridge. The highly weathered sandstone gives substantially younger 10Be ages than the adjacent erratics. The exposure ages from the Kanin Peninsula suggest that the last deglaciation of this area took place between 55 and 37 10Be kyr ago, in agreement with a preceding Kara Sea glaciation (55-45 kyr BP). The northwest coast of the peninsula was probably just outside the maximum limit of the last Scandinavian glaciation (20-17 kyr BP). Glacial erratic exposure ages from the Timan Ridge suggest that the 55-45 kyr BP Kara Sea glaciation reached the northern part of the ridge. The exposure dates do not show conclusive evidence regarding the existence of a Timan Ridge ice cap. 相似文献
17.
Granitic constituents suggest distant plutonic sources for sherds representing four of six low‐fired brown ware pots and for eight of ten sandstone artifacts from Lost Dune (35HA792), a Late Prehistoric bison processing camp in Harney Basin of southeastern Oregon, a Tertiary volcanic and sedimentary region. Eight sandstone artifacts match granite‐derived sandstone near Oregon's Owyhee River, and three former pots match altered granite and rhyolite in Idaho's Owyhee Mountains. A fourth corresponds to mixed hydrovolcanic basalts near the sandstone abrader source. The sources delineate a 30 × 70 km area > 100 km from Lost Dune. Two other pots and two milling stones match deposits near this area and elsewhere. The determined sources suggest people who used Shoshoni pots and knives at Lost Dune resided in southeastern Oregon. Pots with temper from elevations above 1500 m or recovered as sherds above 1500 m might be made in summer root‐digging camps. © 2002 Wiley Periodicals, Inc. 相似文献
18.
Crayfish produce small button‐like gastroliths in their stomachs. These curious calcitic objects are increasingly common in lakes and streams in the UK and Europe as the invasive American crayfish increase their domination of freshwater environments. These stomach stones are also present in the geological record. 相似文献
19.
柴达木盆地石炭系多发育致密化储层,后期成岩改造尤为重要。目前在盆地东部多口钻井中发现石炭系存在孔洞、溶缝以及溶蚀残丘等不同尺度的岩溶改造迹象,且个别钻井在该段有明显气测异常。因此,岩溶缝洞特征、缝洞测井响应是该区石炭系储层的基础问题。鉴于此,以柴东钻井资料为基础,岩石学-测井地球物理方法相结合,开展古岩溶缝洞单元测井响应研究。研究表明,石炭系岩溶缝洞可划分为风化壳型岩溶和沿构造断裂有关的岩溶缝洞两种类型。岩溶多见于克鲁克1~2段、扎布萨尕秀组以及怀头他拉与上覆层界限处。缝洞横向可对比,往往自然电位负异常,自然伽马中低值（20.5~35.0 API）,声波时差异常增高,中子（13.9%）、密度（2.50 g/cm3）有一定镜像特征,电阻率（215.2~1100.0 Ω·m）低于围岩（>1100.0 Ω·m）。该区成熟的风化壳型岩溶缝洞在测井上表现为五个结构单元,上覆层、渣状层、溶洞层、裂隙-溶缝层、致密层。岩溶风化壳缝洞为该区主要岩溶缝洞类型,改造强度大于裂缝型,且共生。二者改造机制各异,但改造时间近似,推测为印支期的构造响应,时间持续到早中侏罗世甚至到早白垩世结束。 相似文献
20.
PETER J. McCABE 《Sedimentology》1977,24(2):271-290
Channels, with maximum depths of over 40 m, have been cut into the top of a coarsening upward sequence, in the Upper Carboniferous of northern England. The channels are interpreted as deep, distributaries cut into delta slope deposits. Giant cross-bed sets, up to 40 m thick, are the major channel infilling facies. Internal erosion surfaces occur within the giant cross-beds and some are draped by micaceous, silty sandstone. Previously interpreted as deltaic sedimentation units, the cross-beds are now thought to have been produced mainly by side attached, alternate bars and the drapes are interpreted as low stage deposits. Cosets of medium scale cross-beds overlie the giant cross-beds. These are thought to be deposits of dunes and smaller bars on top of the transverse bars and in the shallower parts of the distributary. The giant cross-beds are commonly underlain by unlaminated sandstone but may be underlain by undulatory bedding. The latter was apparently produced by ridges, parallel to the current, spaced between 9 and 23 m apart. The north of England appears to have had a major river by present day standards, for at least part of the upper Carboniferous. 相似文献