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浅变质
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  low metamorphic
     It is the basic unit for 1∶50000 regional geological mapping in highly deformed middle low metamorphic regions.
     构造变质岩石地层单位是强变形、中浅变质沉积岩区1∶5万填图的基本填图单位。
短句来源
     The ooze water of these various types belongs to low metamorphic water.
     这些不同类型的软泥水均属软泥阶段的浅变质水。
短句来源
     Illite crystallinity of the buried hill is 122~150,bo-value is 9.030~9.066, showing low metamorphic greenschist facies.
     潜山地层中的伊利石结晶度为 12 2~ 15 0 ,b0 值为 9 0 30~ 9 0 6 6 ,变质程度为浅变质绿片岩相 ,而邻近区域只有中元古界具有这样的特征 ;
短句来源
     According to the host rock, the main deposits and/or mineralization points can be divided into 7 types: in mafic ultramafic rocks, in porphyry rocks, in granites, in skars, in land facies volcanic rocks, and in low metamorphic carbonaceous clasolites.
     主要已知矿床 (点 )按其容矿围岩可分为镁铁 -超镁铁岩型、斑岩型、花岗岩型、矽卡岩型、陆相火山岩型、陆相沉积岩型、浅变质含碳碎屑岩型。
短句来源
     The fault zone at the south edge of the Nalati tectonic belt is apparent , and the Paleozoic low metamorphic black complex is distributed over the south of the fault.
     那拉提构造带南缘断裂明显 ,南侧为古生代浅变质黑色岩系 ;
短句来源
  “浅变质”译为未确定词的双语例句
     The values o f δ34S of the pyrites in the ores of Dabeiwu gold deposit range from -4.9‰to -7.1‰, showing that the sulphur was dominantly derived from the epimetamorphos ed marine sedimentary rock series.
     大背坞金矿床中黄铁矿δ34S同位素变化范围(-4.9‰~-7.1‰)反映出硫主要来源于双桥山群浅变质海相沉积岩系;
短句来源
     THE GEOLOGICAL CHARACTERISTICS OF ABROAD SUPERLARGE METAMORPHIC MICROCLASTIC ROCKTYPE GOLD DEPOSITS
     国外超大型浅变质细碎屑岩型金矿床的地质特征
短句来源
     SHRIMP U-Pb dating of zircons from low-grade metamorphic rocks in the Rola Kangri junction zone, northern Tibet, China.
     藏北若拉岗日结合带中的浅变质地层及其锆石SHRIMP U-Pb年龄测定
短句来源
     Characteristics and Classification of Tectonite of Ductile Shear Deformation in Epimetamorphic Microclastic Rocks
     浅变质细碎屑岩中韧性剪切变形构造岩特征及其类型划分
短句来源
     The Dabeiwu ductile shear zone, formed in the epimetamorphic clastic rocks, has typical features and particular discerning signs.
     在对大背坞韧性剪切带进行系统研究后 ,建立了一套浅变质碎屑岩中进变质韧性剪切带的识别标志 ,进而对该区韧性剪切带进行划分和厘定 ;
短句来源
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  相似匹配句对
     The deposit occured in siiurian system of epizonal metamorphism.
     矿床产于变质志留系中。
短句来源
     metamorphic belt in China.
     变质带。
短句来源
     On low-grade metamorphic rock within Dabie-Sulu ultrahigh pressure metamorphic belt.
     大别-苏鲁超高压变质带内部的变质
短句来源
     Superficial View of Electronic Commerce
     论电子商务
短句来源
     Superficial view of loci of Qi
     气穴
短句来源
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  low metamorphic
FeS contents of sphalerites coexisting with pyrite and pyrrhotite outside and inside pressure shadows indicate much higher pressures (7.7 to 9.0 kbar) than those inferred from stratigraphic reasoning and the low metamorphic grade.
      
Luis, Portugal is located in the southernmost linear belt of outcropping low metamorphic grade deformed Palaeozoic rocks (Famennian) in the SW part of the Iberian Pyrite Belt.
      
Tourmalinites occur at five stratigraphic levels within the low metamorphic grade multiply deformed Lower Proterozoic metasediments and metavolcanics of the Golden Dyke Dome.
      
Diffusive mass transfer, involving pressure solution and oriented overgrowth of pyrite is the main deformation mechanism in pyrite deposits at low metamorphic grades.
      
The district is divided into three areas of low (metamorphic zones I, II), medium (zones IIIa-V) and highδ13Cgr value (zones VIa-VII) areas.
      
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The feature of the aeromagnetic field in the central part of Xizang, with negative values as its background, reveals the flexible nature of the basement, which is composed of low-grade parametamorphic rocks.The North Xizang fault is not clear in the aeromagnetic map.Yarlung Zangbo rift is a suture line between the colliding plates. The aeromagnetie anomalous zone over the rift, is characterised by high intensity, excellent continuity and great extention. Geological and various geophysical data indicate that...

The feature of the aeromagnetic field in the central part of Xizang, with negative values as its background, reveals the flexible nature of the basement, which is composed of low-grade parametamorphic rocks.The North Xizang fault is not clear in the aeromagnetic map.Yarlung Zangbo rift is a suture line between the colliding plates. The aeromagnetie anomalous zone over the rift, is characterised by high intensity, excellent continuity and great extention. Geological and various geophysical data indicate that the fault plane is inclined to the south.Since the beginning of the upper Triassic epoch, the Indian plate upthrusted to the north over the Tethys oceanic crust and led to the closure of the Tethys in Eocene epoch. After the collision of the two plates, the obduction movement was replaced by the pushment of the Indian plate towards the southern edge of the Eurasian plate.

以负磁场为背景的航磁特征,揭示了基底是由浅变质的副变质岩组成的,属于柔性基底。 藏北断裂在磁场图上不明显。 雅鲁藏布江断裂是举世闻名的缝合线。反映雅鲁藏布江断裂的航磁异常带,具有强度大、连续性好和长度大的特点,为世界上罕见的大陆线性异常带。地面地质和各种地球物理资料查明断面是南倾的。 晚三迭世开始,印度板块在特提斯洋壳上向北仰冲,并导致特提斯在始新世的关闭。两大陆碰撞后,仰冲运动结束,代之以印度板块对欧亚板块南缘的推挤。

Ⅰ. Stratigaphic Summary The Yangjiaping section in Shimen County is located in the northern border of Hunan Province. Geotectonically it lies on the northern limb of Dongshanfeng anticlinorium of the southern margin of Yangtze platform. In tthis section the Precambrian system is well developed, and the upper and lower boundaries, are well defined. I is stratigraphical sequence is continuous and the geological structure is simple, while a lot of stromato-lites, microfossils, and small shelly fossils can be collected...

Ⅰ. Stratigaphic Summary The Yangjiaping section in Shimen County is located in the northern border of Hunan Province. Geotectonically it lies on the northern limb of Dongshanfeng anticlinorium of the southern margin of Yangtze platform. In tthis section the Precambrian system is well developed, and the upper and lower boundaries, are well defined. I is stratigraphical sequence is continuous and the geological structure is simple, while a lot of stromato-lites, microfossils, and small shelly fossils can be collected in this section. The total thickness is 1193. 34m. This section can be divided as follows: Overlying strata; lower cambrian Yangjiaping Formation Conformity Upper Sinian Dengying Formaton 176. 44m. in thickness. Upper Member, greyish white, lightgrey midium to thick bedded micro-litic dolomite, Clastic dolomite silicified muddy clastic dolomite, Sparry clastic dolomite. 69. 67m. Lower Member, dark grey thin-midium bedded microlitic dolomite, Siliceous dolomite, calcareous dolomite. 106. 77m. Conformity Upper Sinian Doushantuo Formation 475. 68m. Upper Member; grey, greyish-white midium thick micro-granular clastic dolomite, phosphoric calcium-bearing dolomite, intercalated with a few dolomitic limestone, phosphorite. 84. 53m. Lower Member; greyish black thin bedded micrite micro-granular car-bonaceous dolomite, dolomitic limestone, calcareous dolomite and a few pelitic siltstone, sandstone, carbonaceous slaty shale. 391. 15m. Conformity Lower Sinian Nantou Formation 719. 77m. Upper Member; grey massive morainic arenaceous mudstone, gompho- lite and siltstone with morainic pebbles. 68. 24m. Lower Member; dark grey massive arenaceous mudstone with mora-inic pebbles and a few pebbles-bearing sandstone intercalcated with slaty shale. 11. 53m. Conformity Lower Sinian Xiangmeng Formation 11. 93m. Dark-grey, greyish black slaty shale, carbonaceous slaty shale, Mn-bearing slaty shale intercalated with lens of dolomite. Conformity Lower Sinian Dongshanfeng Formaton 3. 7m. Dark-grey massive arenaceous slate with morainie pebbles, pebbles-bearing sandstone. Disconformity (Xuefeng movement) Presinian Banxi Group Xieshuihe Formation 260. 07m. Upper Member; purplish red, greyish green thick bedded medium-coarse granular slight metamorphic feldspathic quartz-sandstone, quartzose-sand-stone, siltstone, arenaceous slate and slate. 97. 60m. Lower Member; purplish red, greyish white quartzose conglomerate, arenaceous conglomerate, pebbles-bearing sandstone, coarse granular qu-artz-sandstone intercalated with a few quartz-siltstone and slate. 162. 47m. Conformity Presinian Banxi Group Madiyi Formation 175. 50m. Upper Member; purplish red, greyish green medium-thick bedded sli-ght metamorphic medium-fine granular quartz-sandstone, rudaceous sand-stone, siltstone.slate etc. 159. 37m. Lower Member; purplish red thick bedded massive slight metamorphic quartzose conglomerate, arenaceous conglomerate, pebbles-bearing sands-tone, coarse sandstone intercalated with a few arenaceous slate. 16. 13m. Unconformity (Wuling movement) Underlying strata; presinian Lengjiaxi Group. Ⅱ. Geochemical characteristics of rocks The geochemical characteristics of rocks of precambrian system in Yangjiaping section may be mentioned as follows: 1. Si. Al. Ca. Mg. K. Na. Fe. being the pretty high content chemi-cal elements, may be further subdivided into four assemblages, i. e. Al. Ti. B. Fe. Mn; Si. K. Ba. Cu. Pb; Ca. Mg. Na. P. Sr; and Cr. Ni Co. V. Zn. 2. Elements with closely correlative relationships are: Mn-B-Al-Ti; Sr-P-Ca-Mg; Cr-Ni-V; and Ba-Cu-Pb. 3. Variables of CaO-MgO and TiO_2-Fe_2O_3-K_2O-Al_2O_3-Na_2O respecti-vely control the carbonate rocks and the silicate rocks and both of them are in reverse relation which have been throughout the course proved by the mathematical method of factor analysis. 4. The result of the cluster analysis shows that the Fe_2O_3-Al_2O_3-K_2O- TiO_2-Na_2O can be clustered together, and represents the clay-rock, siltsto-ne and sandstone with pretty high content of the feldspar, while the FeO and MnO can be clustered together and represents the carbonate rocks. Ⅲ. Palaeomagnetic characteristics of rocks The palaeomagnetic characteristics of upper precarmbrian system at Yangjiaping section are as follows: 1. During the time of sedimentation of Precambrian rocks the palaeo-magnetism was basically located in the normal polarity epoch. The average palaeolatitude of Madiyi Formation, Xieshuihe Formation, Dongshanfeng Formation, Xiangmeng Formation, Nantuo Formation, Doushantuo Forma-tion and Dengying Formation were 30.49°, 19.93°, 12.25°, 23.32°, 9.84°, -20.20°, -19.46°, respectively. 2. There were three times of polar reversion during the deposition of precambrian rocks. One of the three times happened at the base of Cam-brian, and it may be served the proof of the boundary of Sinian and cam-brian systems, the other two occured in Madiyi Formation of Banxi Group and its cause of formation needs further research. 3. By comparing Upper precambrian Apw path at Yangjiaping section with that of Yangtze gorges, an Upper Precambrian Apw path at studied area has preliminaryly been set up. Ⅳ. Palaeontological characteristics There are chiefly micropaleoflora, stromatolites, and a few trace fossils in the Precambrian system of Yangjiaping section, the micropaleoflora may be subdivided into two assemblages: Banxi group-lower Sinian system consists of the first assemblage, They belong to unicellular alage Sphaeromorphitae (being the dominant eleme-nts) and numerous fragments of brown algae, among them, the sphaerical forms are dominant, and fibre fragments are secondary, and a few triangu-lar, quadrate or irregular forms, the diameters of most individuals are large than 50μ with coarse surfaces and simple-complicated ornament. The second assemblage consists of the micropaleoflora of Upper Sinian system, presenting acantomorphitae and a few elements of new genera and species of prismatomorphitae and Lophosphaeridium yichangense, Hubeis- phaera sp., which have never been seen in the first assemblage. The stromatolites are distributed in Doushantuo Formation and Dengy-ing Formation. In these formations the main elements; Nucleelo f., Boxonia f., Gymnosolen f., Baicalia f., etc. are dominant. The trace fossils consist of some irregular tubular bodies. V. Paleoglaciers The glacier periods of early Sinian may further be subdivided into two subglacier periods and an inter-glacier period. The Nantuo Formation is typical sedimentary type of morainic facies. The Xiangmeng Formation is the deposits of Xiangmeng inter glacier Period. The Dongshanfeng form-ation is pretty typical sedimentary type of glaciomarine facies. The Com-mon characteristics of the two types of glacier sediments are as follo-ws. 1. The contents of moraine are complicate but the main compositions are basically identical. 2. The shapes of pebbles are various but the chief outlines, Sphericiti-es and roundnesses are similar. 3. The uneven distribution, different sizes, random arrangements, great changes in longitudinal distribution and without definite rules are characters of pebbles. 4. The Striae, carve-traces, pressed crevasses, pressed pit., slide tra-cks and grinding pebbles are all present. The differences of the two types of the glacier sediments are: 1. The thickness of glacier marine deposit is rather stable and with a few intercalated beds that reveals the characteristics of marine deposit. but the thickness of morainic facies deposit varies greatly, intercalated beds almost absent, bedding also invisible. 2. There are litlle quantities of pebbles in glaciermarine deposit and with few boulders, ice slide tracks and grinding pebbles. The falling stone structures are well developed. On the contrary, the pebbles of morainic facies are very much with a definite of boulders. The ice slide tracks and grinding pebbles are generally seen, without falling stone-structures. Ⅵ. Sedimentary facies 1. The lower member of madiyi Formation is of meanderring river de-posit, and the upper member is of tidal flat deposit of river mouth gulf. 2. The lower member of Xieshuihe Formation is of the deposit of braided river, The upper member is of tidal flat deposit of river mouth gulf. 3. The Dongshanfeng Formation is the deposit of glacialmarine. 4. The Xiangmeng Formation is the deposit of subtidal gulf. 5. The lower member of Nantou Formation is the deposit of glacier-marine, the upper member is deposit of moraine. 6. The lower member of Doushantuo Formation represents the deposit of subtidal basin, the upper member is the deposit of subtidal flat carbo-nate rock. 7. The lower part of Dengying Formation represents the deposit of subtidal half closed flat shallow beach and interbeach, the upper member is the deposit of subtidal flat margin gradient. Based on the characteristics of isotopic age data, paleontology, crustal movement, and paleoglacier, the Precambrian System may be correlated as follows: The Yangjiaping Formation rich in small shelly fossils is the equivale-nce of Tianzhushan Formation in east of the Yangtze Gorges, the Meishu-cun Formation in eastern Yunnan, the Maidiping Formation in Sichu-an. The upper morainic Nantou formation may be correlated with Nantou formation in Yunnan and in east of the Yangtze Gorges, Silikou Forma-tion North of Guangsi, Leigongwu Formation in Western Zejiang and Nor-theast of Jiangsi. The lower Morainic Dongshanfeng Formation is the equivalence of Gucheng Formation in Changyang, Hubei, the Changan Formation-lover Member of Fulu Formation in eastern Guizhou and Guangsi. The Xueshuihe Formation is suitable to be correlated with the Liantuo Formation east of the Yangtze Gorges, the Qingshuijiang Formation-Rongli Formation east of Guizhou, Gongdong Formation, north, of Guangsi, Kaiji-anqiao formation in southwestern Sichuan. The Madiyi Formation may be correlated with Jialu Formation, Fan-shao Formation of eastern Guizhou. Baizhu Formation, Hetong Formation of Northern Guangsi. the Suxiong Formation of southwestern Sichuan. The Lengjiaxi Group may be correlated with the Fanjingshan group of eastern Guizhou, the Sibao group of Northern Guangsi, the Kunyang group of eastern Yunnan, the Ebian group of southwestern Sichuan, the Sandouping group of the eastern Yangtze Gorges.

一、地层剖面剖面全长2公里,出露较好,构造简单,层序连续完整,顶、底界接触关系清晰,产较丰富的微古植物、叠层石、小壳动物等古生物化石,可分一群、一系、两统、七组。地层总厚度为1193.34米。自上而下分为: 上覆地层:下寒武统杨家坪组黑色炭质页岩与薄层硅质岩互层。整合震旦系灯影组 176.44米上部:由灰白色、浅灰色中—厚层粉晶云岩、粒屑云岩、硅化泥晶云岩、亮晶粒屑云岩等组成。 69.67米下部:由深灰色薄—中厚层泥—粉晶云岩、硅质云岩、灰质云岩等组成。 106.77米整合陡山沱组 475.68米上部:由灰色、灰白色中—厚层状粉晶粒屑含灰质云岩、含磷质云岩、含硅质云岩夹少量白云质灰岩、磷块岩等组成。 84.53米下部:由灰黑色薄层泥晶—粉晶炭质云岩、白云质灰岩、灰质云岩及少量泥质粉砂岩、砂岩、炭质板状页岩等组成。 391.15米整合南沱组 90.02米上部:由冰碛砾砂质泥岩、冰碛砾泥岩及冰碛砾粉砂岩等组成。 78.49米下部:由深灰色冰碛砾砂质板岩、冰碛砾板岩及少许冰碛砾砂岩、板状页岩等组成。 11.53米整合湘锰组:由深灰色、灰黑色板状页岩、炭质板状页岩、含锰板状页岩及夹白云岩透镜体等组成。 11.93米整...

一、地层剖面剖面全长2公里,出露较好,构造简单,层序连续完整,顶、底界接触关系清晰,产较丰富的微古植物、叠层石、小壳动物等古生物化石,可分一群、一系、两统、七组。地层总厚度为1193.34米。自上而下分为: 上覆地层:下寒武统杨家坪组黑色炭质页岩与薄层硅质岩互层。整合震旦系灯影组 176.44米上部:由灰白色、浅灰色中—厚层粉晶云岩、粒屑云岩、硅化泥晶云岩、亮晶粒屑云岩等组成。 69.67米下部:由深灰色薄—中厚层泥—粉晶云岩、硅质云岩、灰质云岩等组成。 106.77米整合陡山沱组 475.68米上部:由灰色、灰白色中—厚层状粉晶粒屑含灰质云岩、含磷质云岩、含硅质云岩夹少量白云质灰岩、磷块岩等组成。 84.53米下部:由灰黑色薄层泥晶—粉晶炭质云岩、白云质灰岩、灰质云岩及少量泥质粉砂岩、砂岩、炭质板状页岩等组成。 391.15米整合南沱组 90.02米上部:由冰碛砾砂质泥岩、冰碛砾泥岩及冰碛砾粉砂岩等组成。 78.49米下部:由深灰色冰碛砾砂质板岩、冰碛砾板岩及少许冰碛砾砂岩、板状页岩等组成。 11.53米整合湘锰组:由深灰色、灰黑色板状页岩、炭质板状页岩、含锰板状页岩及夹白云岩透镜体等组成。 11.93米整合东山峰组:由深灰色、灰色块状含冰碛砾石砂质板岩、含冰碛砾石砂岩等组成。3.70米假整合板溪群渫水河组 260.10米上段:由紫红色、灰绿色粗—细粒浅变质长石石英砂岩、石英砂岩、粉砂岩、砂质板岩、板岩等组成。 97.60米下段:由紫红色、灰白色厚层—块状变质石英砾岩、砂砾岩、含砾砂岩、粗粒石英砂岩夹少量石英粉砂岩、板岩等组成。 162.47米整合马底驿组 175.50米上段:由紫红色、灰绿色中—厚层状浅变质中—细粒石英砂岩、长石石英砂岩、含云母砂岩、粉砂岩、板岩等组成。 159.37米下段:由紫红色厚层—块状变质石英砾岩、砂砾岩、含砾砂岩、石英粗砂岩夹少量砂质板岩等组成。 16.13米不整合下伏地层:冷家溪群变质砂岩、板岩互层。二、岩石地球化学据1395个岩石光谱样、47个化学样的分析数据,用因子分析、聚类分析研究了各类岩石地球化学分类、元素间相关关系;用有序地质体最优分割法及对分移动窗口法研究了剖面上层序的划分。初步掌握了该剖面地球化学特征如下: 1.平均化学成分以Si、Al、Ca、Mg、K、Na、Fe为主,可划归A1、Ti、B、Fe、Mn;Si、K、Ba、Cu、Pb;Ca、Mg、Na、P、Sr;Cr、Ni、Co、V、Zn等组合。 2.元素相关关系较密切的有Mn-B-A1-Ti;Sr-P-Ca-Mg;Cr-Ni-V;Ba-Cu-Pb等,其中尤以Si、P、Ca、Mg关系密切。 3.元素丰度在时间上的演化规律与剖面上地层划分基本上相吻合。 4.因子分析表明变量CaO—MgO控制碳酸盐岩;变量TiO_2—Fe_2O_3—K_2O—A1_2O_3—Na_2O控制硅酸盐岩,且两者始终保持反间关系。 5.聚类分析表明Fe_2O_3、Al_2O_3、K_2O、TiO_2、Na_2O聚类一起,代表了粘土岩、粉砂岩、含长石较高的砂岩类;FeO、MnO聚集一起,反映了还原条件下形成的岩石;CaO、MgO聚类一起,代表了碳酸盐岩类岩石。三、古地磁据30个样品的磁测数据,获得了磁性地层的初步成果如下: 1.晚前寒武纪沉积期,基本上处于正极性时期,同时均处于低纬度地带,其中马底驿组平均古纬度为30.49°,渫水河组为19.93°,东山峰组为12.25°,湘锰组为23.32°,南沱组为9.84°,陡山沱组为-20.20°,灯影组为-19.46°。 2.晚前寒武纪沉积期,经历了三次极性倒转,其中寒武系底部求得的北磁极落在南半球的东经62.72°,南纬8.67°,该次极性倒转可作为震旦系与寒武系分界的佐证。另两次极性倒转发生在马底驿组沉积期内,其成因尚待进一步研究解释。 3.视古地磁极迁移轨迹表明,距今1000百万年前冷家溪群开始,地磁极位置从163.42°东、65.42°北起向西北方向迁移;板溪群时期,则在北极点附近绕动,而后向北西方向迁移;震旦纪时,磁极位置由早—晚,由5.65°—327.60°东、47.05°—39.00°北之间绕动。由于经验不够,又因受仪器设备限制,精度尚待进一步深化。但作为资料积累,对建立南方晚前寒武纪古地磁年表无疑将是有益的。四、古生物主要为微古植物、叠层石及一些虫迹化石。微古植物可建立两个组合:板溪群—下震旦统中微古植物为第一组合,是以球藻亚群为主的单细胞藻类及一些褐藻碎片,形态多为球形,其次为纤维状碎片,少数为三角形、方形及不规则形状,多数个体大于50微米,表面粗糙,有简单—复杂的纹饰。该组合近似蓟县青白口系及峡东莲沱组—南沱组中微古植物特征。上震旦统微古植物为第二组合,它除了继承下震旦统及板溪群中微古植物的许多分子外,更重要的是出现了刺球藻亚群及棱面藻亚群中少数分子及前所未见的Lophosphaerium yichangense, Hubeisphaera sp.等新属新种。该组合和南方各地上震旦统微古植物特征基本一致。叠层石产于陡山沱组及灯影组,主要为Nucleela f., Boxonia f., Gymnosolen f., Baicalia f. 等。虫迹化石较普遍,主要为一些不规则形管状体。五、古冰川统称早震旦世冰期,可进一步划分两亚冰期及一间冰期。南沱组代表南沱亚冰期沉积,为较典型的冰碛相沉积类型;湘锰组代表湘锰间冰期沉积;东山峰组代表江口组亚冰期沉积,为较典型的冰海沉积类型。两种沉积类型具有如下的共性: 1.冰碛物成分复杂,随地而异,但砾石的主要组分基本相同。 2.砾石的形状多种多样,但主要形态、球度及圆度相近似。 3.砾石分布不均匀,大小不一,排列杂乱,在纵向分布上,变化急剧,无一定规律。 4.均具有条痕、刻痕、压裂、压坑等冰溜遗痕及研磨砾石。上述共性说明冰海相与冰碛相有相近的亲缘关系。两种沉积类型有如下差别: 1.冰海相沉积厚度较稳定,具有少量夹层,其层理显示海相沉积特征;冰碛相沉积厚度变化大,几乎无夹层,不显层理。 2.冰海相沉积砾石数量少,大砾石少,冰溜遗痕及研磨砾石少见,落石构造非常普遍;冰碛相沉积砾石数量多,有一定数量大砾石,冰溜遗痕及研磨砾石普见,无落石构造。上述差异的原因,主要与冰川进入海洋的部位有关。六、沉积相共划分了3相组、4相、7亚相、16微相及62相段: 1.马底驿组沉积相下段曲流河沉积:结构成熟度低,杂基—颗粒支撑,板状及平行层理为主,剖面二元结构明显,粒度分析多数样品落在河流范畴。上段河口湾潮坪沉积:结构成熟度低,楔状、槽状、脉状再作用面、人字形等层理及波痕、泥裂大量出现,薄互层发育,粒度分析多数样品落在海(湖)滩范畴,部分样品落在河流范畴。 2.渫水河组沉积相下段辫状河流沉积:矿物及结构成熟度均较低,颗粒支撑为主,大型楔状、槽状交错层理发育,剖面二元结构发育不全,绝大多数样品落在费里德曼标准偏差散点图河流范畴。上段河口湾潮坪沉积:结构成熟度较低,杂基支撑,楔状、槽状、爬升、脉状、鱼骨状等层理及波痕、泥裂普见,薄互层发育,粒度分析结果,样品一半落在海洋,另一半落在河流范畴。 3.东山峰组冰海相沉积:矿物及结构成熟度低,杂基支撑,具微层理,落石构造发育,粒度分析参数值反映为中值,变化范围大,峰态及标准偏差变化范围小,偏度全为负偏。 4.湘锰组河口湾潮下海湾沉积:富含有机质、藻类及硫化物,常夹含锰碳酸盐岩及锰矿层,细纹状水平层理发育。 5.南沱组沉积相下段与东山峰组沉积相类似,为冰海相沉积,上段为冰碛相沉积。矿物及结构成熟度低,杂基支撑,不显层理,冰溜遗痕及研磨砾石普见,粒度参数值反映峰态中等—尖窄,偏度为极负偏。 6.陡山沱组沉积相下部浅海台地潮上—潮间—潮上带沉积:富含有机质、藻类及硫化物,岩石化学成分中Fe~(3+)/Fe~(2+) <1,微量元素Rb/K=0.0037,水平层理发育。上部浅海台地碳酸盐岩潮坪沉积:富含藻叠层石,岩石化学成分Fe~(3+)/Fe~(2+)<1,Rb/K=15.30,平行层理为主,局部有小—中型楔状交错层理。 7.灯影组沉积相下部浅海台地潮间—潮上带沉积:富含藻叠层石,钙球藻及少量藻丝体,泥—粉晶结构,水平层理为主,条纹状及网格状泥裂发育。上部浅海台地潮间—缘斜坡—盆地边缘:富含大型柱状叠层石,常见圆形或椭圆形、竹叶状砂屑、砾屑,具有大型滑动构造及包卷层理。七、划分与对比 (一)划分 1.震旦系与寒武系界线(顶界) 分界的主要依据为小壳动物群,已于188层炭质页岩与薄层硅质岩中发现:Protohertzina sp., P. unguliformis, P. anabarica, Turcutheca sp., Torellella sp. 等,此外尚见Oxe-aklostera monaxon等海绵骨针、微型海绵骨针及分类位置尚存疑的蚕形、球形类化石,其中Protohertzina sp., 为钱逸建立的早寒武世早期小壳化石带第一组合中的分子。其二,同时于188—190层中发现极为丰富的微古生物化石,计有蓝藻门、绿藻门、红藻门、细菌、疑源类及分类位置不明的藻微化石,共18属、19种(内3个新属、9个新种、9个未定种、2个未命名化石),它们保存好,属种类型复杂,除少数分子分别见于云南、四川下寒武统梅树村组、麦地坪组外,多数分子亦为首次发现,是国内已发现的相当层位微化石最特殊的类型,且与震旦系上统的微古化石组合有明显差异。其三,在震旦系顶部(187层)云岩中发现有虫管化石。综上三者依据对湖南湘西北地区震旦系与寒武系界线的划分和对比进行了论述,并将其界线置于产小壳化石的188层之底部。 2.板溪群与冷家溪群界线(底界) 界线置于1与0_2层之间,划分的主要依据为: (1)板溪群与冷家溪群呈高角度不整合接触,为一理想界面。 (2)冷家溪群为复理石建造,板溪群为类磨拉石建造。 (3)B、P、K、Cr、V、Sr等元素在冷家溪群顶部出现低值,进入板溪群后则出现高值。 (4)冷家溪群多数分子为一些形状简单、个体微小、膜壳较薄、表面光滑的球形藻类。板溪群多数分子则为形状较复杂、个体较大、膜壳较厚、表面具纹饰的藻类。 3.震旦系与板溪群界线界线置于102与103层之间,主要依据为古气候标志,即将冰成地层置于震旦系底部,这种意见的理由为: (1)早震旦世冰成地层遍布五大洲,便于世界对比。 (2)峡东震旦系经历了两次构造运动,缺失不少地层,如以冰成地层为底界,可摈除其中较大的一次构造运动的影响。 (3)如以莲沱组为底界,震旦纪时限大于2亿年,如从冰成地层开始,震旦纪时限小于1.5亿年,更符合建立新纪的时限要求。 (二)对比对比的依据主要是同位素、古生物及构造运动、古冰川,其次可考虑沉积建造、变质程度、岩性组合等因素。据此可作如

The depth of the magnetic basement east of the great regional fault (the western fault of the East China Sea basin) is generally 7-9km. It deepens towards the direction of the fault. It is infered that pre-Miocene solid and metamorghic about a few to near 10km. thick exists on the basement.

区域性大断裂(东海盆地西缘断裂)以东的磁性基底深度一般为7—10公里,并向断裂方向加深。推测基底以上的地层可能有数公里至近10公里弱磁性的、已固结或浅变质的前中新世岩层存在。 区域性大断裂以西区域,可能存在两个磁性层,即一个为中生代岩浆侵入体和近地表浅层覆盖的火山岩层;另一个磁性层则位于更深处。两个磁性层之间可能包含中生界中早期及前中生界的巨厚弱磁性变质岩系。 在两条与海岸近于平行的基底深拗陷带之间是一条基底相对隆起带,是深断裂岩浆活动的产物。 三条带的延伸,向北可能终止于东福山北东东向断裂带,向南则可能与福建省海岸平行至少延至台湾海峡南端。

 
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