白垩纪的
- 与 白垩纪的 相关的网络例句 [注:此内容来源于网络,仅供参考]
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The composi-tion of the seawater has changed rapidly since Phanerozoic, and the prolonged mineralogical changes of marine non-skeletal limestone and potash evaporates occurred in a phase on a 100-200 Ma.
结果表明:显生宙以来海水组分发生变化,经海相非骨骼灰岩和钾盐蒸发岩矿物学研究,发现这两种沉积岩长期以来连续变化,在"文石海"是MgSO4型蒸发盐,在"方解石海"是KCl型蒸发盐,从白垩纪晚期、第三纪早期的底部石盐溴含量及矿物学特征表明,此时处于"方解石海",古海水组分的特点是造成缺硫酸盐型钾盐矿床形成的物化基础;通过NaCl-KCl-MgCl2-H2O和NaCl-KCl-MgCl2-CaCl2-H2O两个体系相图的分析认为,当时所形成的成钾原始体系母液是高镁、低钾氯化物型的卤水,在母液蒸发过程中,由于原始海侵母液与残余高镁母液的掺杂作用,致使结晶路线直接从氯化钠区到E点母液或光卤石与氯化钠共饱线上,而没有通过氯化钠和氯化钾的共饱线,因而在矿体中氯化钾相很少或几乎不存在,由于外界CaCl2型水体的掺杂,使成钾母液进入光卤石相区,随着蒸发的进行,最终形成溢晶石矿物。
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The Dabie Mountains are unique among ultrahigh pressure metamorphic terranes in having the most profound post collisional plutonism The Mesozoic shoshonitic and calc alkaline intrusive rocks can be divided into three groups with different isotopic ages, rock assemblages and chemical features Group I consists of late Triassic (~ 210 Ma) mafic monzodiorites It could have been generated by partial melting of enriched subcontinental lithosphere mantle due to slab breakoff Group II consists ma...
第 I组,主要由晚三叠世(约210 Ma)二长闪长岩辉长岩体组成,它可能是在板片断离过程中富集的大陆岩石圈地幔部分熔融的产物;第I I组,由中侏罗世-早白垩世(160~120 Ma)的角闪石英二长岩、黑云母二长花岗岩和正长花岗岩组成,主要是由幔源岩浆的分离结晶与地壳混染共同作用的产物;第II I组,以白垩纪(125~95 Ma)的花岗岩和花岗斑岩为代表,是在热穹窿作用过程中大别杂岩深熔作用和高度演化的产物。
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Results show that the Spiti shale in Zanskar terminated 15Ma later than that in southern Tibet, while the lowermost Cretaceous quartz sandstone in Zanskar appeared 18Ma later than that in southern Tibet. The age of volcanic sandstone in southern Tibet is very poorly time constraint and their deposition occurred somewhere within Berriasian~early Albian. In Thakkhola, the Chukh Group volcanic sandstone are of late Hauterivian-early Albian age (duration about 20Ma), while in Zanskar, the volcanic sandstones facies only appeared in Albian (duration of less than 10Ma). Therefore, it can be concluded that the onsets of both quartz sandstone and volcanic sandstone occurred earlier in eastern Tethys Himalayas than in western Tethys Himalayas .
侏罗纪末~白垩纪初印度大陆的北缘同时期存在大陆向上挠曲,导致陆源碎屑输入量的快速增加,石英砂岩广泛存在;早白垩世火山岩屑砂岩对应着的印度大陆北缘地层侵蚀加深,使得较深部的深成火山岩暴露并遭受侵蚀;石英砂岩和早白垩世岩屑砂岩所代表的印度大陆剥露时间在空间上的&东早西晚&,说明构造运动首先是从特提斯喜马拉雅的东部开始(大印度与澳大利亚的彻底分离),然后逐渐波及西部的,东西时间差为15~20Ma;由于地壳均衡作用,大陆分离后原先地壳挠曲转变为地壳下沉,发生强烈的构造沉降,故Albian之后沉积一套深水环境下的海绿石、磷酸盐和黑色页岩沉积。
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Abundance of salt-alkaline megatherm Classopollis-Ephedripites assemblage in a limited time illustrates a short duration of dry hot climate by latest Cretaceous. Such extreme climatic change and ecologic overturn are possible causes of the dinosaur extinction in the study area. Other factors, such as asteroid impact and large volcanic eruption triggering global mass extinction caused the regional climate change.
嘉荫群上部渔亮子组中膏岩层和耐高温、抗盐碱的克拉梭粉-麻黄粉组合在短时间内的大量出现,说明晚白垩世末期出现有短暂的干热气候,这种气候的突然转变以及伴随的生态系统的紊乱可能是嘉荫地区恐龙大量死亡的重要原因,但不排除诸如天外星体碰撞地球、大规模火山喷发等引发白垩纪末恐龙全球灭绝的因素,后者更可能是引起气候变化的直接因素。
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The extinction or appearance of these Ostracoda always occurred in a short time interval, and can be correlated locally and globally, so they are of importance in bioeventstratigraphy. This article listed six such biological events in Qaidam Basin and discussed their causes. The extinction of Cetacella reflected temperature decrease at global scale and changes of palaeoclimate zones during the latest Jurassic and the earliest Cretaceous; The rapid decline of Cypridea in the earliest Cretaceous may be a result of the strikes of small planets; at the latest middle-Eocene Austrocypris became extinct, and at Oligocene Hemicyprinotus disappeared. These events related to the changes of the geological conditions at that time. The explosion of Cyprideis at the middle-Miocene was because the rise of Qinghai-Xizang Plateau which resulted in the dry climate and development of salt lakes.
这些水生生物的绝灭或发生均很迅速,在区域或全球范围内均可对比,具有生物事件地层学意义:Cetacella属的绝灭可能是侏罗、白垩纪之交全球性的古气候降温和气候带变化在柴达木盆地的反映;早白垩世之后Cypridea的迅速衰退是地外因素灾变的结果;中始新世晚期的Austrocypris的绝灭、渐新世Hemicyprinotus的绝灭都与当时地质条件的改变存在著内在的联系;中中新世Cyprideis的爆发推断是青藏高原隆升,导致气候乾燥、湖水咸化的结果;而晚更新世晚期1。
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This implies a major stage of crustal growth in Proterozoic time and remelting of the crustal material in Early Jurassic time;(5) The Oligocene-Miocene adakites contain magmatic zircons that show similar Hf isotope compositions to the Cretaceous-Paleogene Gangdese batholiths, providing a key constraint that allows evaluation of the nature and timing of crustal thickening in southern Tibet owing to the India-Asia collision; and (6) As a whole, the Hf isotope information observed in zircons from the above Transhimalayan rocks demonstrates a temporal variation in εHf values, and thus TDMC ages, that suggests multiple stages of orogenic or crustal formation events.
五、渐新世、中新世的埃达克岩,其岩浆锆石的铪同位素特徵与白垩纪、古第三纪冈底斯岩浆相似,因而为藏南在印亚碰撞以后,地壳增厚的时间与机制提供了关键性的制约;六、综观上述藏南火成岩中的锆石,它们与时变化的铪同位素初始值及其对应的模式年龄记录了拉萨地块多阶段的造山与地壳形成历史。
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In practical study, the essential flow is""on the basis of the study of the faults, strata denuded thickness and original thickness, analyzing the controlling effect of the faults to the sedimentation and denudation, and combined with the areal geology background, reconstructing the basin prototype of each stage"". 2. As the basic theories and methods of the calculation of the denuded thickness, such as, the methods of cosmogenic nuclides, wave equation, apatite fission track, structural sections, acoustic wave, vitrinite reflection, etc, were argued detailedly , and their applicable ranges were analyzed , the denuded strata thickness of each structural layer layer of pre-Tertiary was reconstructed.
对宇宙成因核素法、波动方程法、裂变径迹分析法、构造横剖面法、声波时差法、镜质体反射率法等计算剥蚀量方法的基本原理进行充分论证、改进,分析了各方法的适用范围,在此基础上,综合充分运用上述方法,计算了济阳坳陷前第三系各构造层在不同时期的剥蚀量,绘制了中生代时期古生界顶面的地层剥蚀量等值线图、新生代时期古生界顶面的地层剥蚀量等值线图、白垩纪沉积时侏罗系剥蚀等值线图、新生代沉积期白垩系剥蚀等值线图、新生代沉积期侏罗系剥蚀等值线图等图件,并通过对古生界地层的热变质程度分析,确定了有1500~2000m的早、中三叠世的原始沉积地层在晚三叠世被剥蚀殆尽。3。
- 推荐网络例句
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According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.
曝气设备的动力效率在叶轮转速为120rpm~150rpm时取得最大值,此时氧利用率和充氧能力也具有较高值。
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The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.
稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世,形体几无变化。
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When I was in school, the rabbi explained everythingin the Bible two different ways.
当我上学的时候,老师解释《圣经》用两种不同的方法。