全文获取类型
| 收费全文 | 302篇 |
| 免费 | 53篇 |
| 国内免费 | 223篇 |
专业分类
| 测绘学 | 1篇 |
| 地球物理 | 46篇 |
| 地质学 | 522篇 |
| 海洋学 | 2篇 |
| 综合类 | 5篇 |
| 自然地理 | 2篇 |
出版年
| 2024年 | 2篇 |
| 2023年 | 7篇 |
| 2022年 | 11篇 |
| 2021年 | 16篇 |
| 2020年 | 21篇 |
| 2019年 | 18篇 |
| 2018年 | 15篇 |
| 2017年 | 24篇 |
| 2016年 | 19篇 |
| 2015年 | 20篇 |
| 2014年 | 15篇 |
| 2013年 | 44篇 |
| 2012年 | 33篇 |
| 2011年 | 18篇 |
| 2010年 | 12篇 |
| 2009年 | 29篇 |
| 2008年 | 19篇 |
| 2007年 | 31篇 |
| 2006年 | 28篇 |
| 2005年 | 20篇 |
| 2004年 | 16篇 |
| 2003年 | 16篇 |
| 2002年 | 2篇 |
| 2001年 | 12篇 |
| 2000年 | 14篇 |
| 1999年 | 14篇 |
| 1998年 | 13篇 |
| 1997年 | 15篇 |
| 1996年 | 13篇 |
| 1995年 | 8篇 |
| 1994年 | 17篇 |
| 1993年 | 18篇 |
| 1992年 | 8篇 |
| 1991年 | 6篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 1篇 |
| 1986年 | 1篇 |
排序方式： 共有578条查询结果，搜索用时 31 毫秒
571.
Precise timing of the India-Asia collision is important to constrain the evolution history of both the Himalayan orogen and the Tibetan Plateau. It has been proposed that the Indian plate first collided with an intra-oceanic arc at ∼55 Ma, and then the composite terrane collided with the Asian continent at ∼35 Ma. The Zedong terrane has been suggested to represent the vestige of such an intra-oceanic arc developed within the Neo-Tethys Ocean, as some volcanic rocks with high K2O have been classified as shoshonites. In this study, we present detailed geochemical and geochronological data of various types of magmatic rocks (including volcanic, cumulate and granitic rocks) widely exposed in the Zedong terrane to constrain the formation age and tectonic setting of the Zedong terrane. We found that the Zedong volcanic rocks belong to calc-alkaline series rather than shoshonites and high K2O contents in some volcanic rocks resulted from alteration. The basalts are highly enriched in LREE and LILE, but strongly depleted in HFSE, indicating they were derived from a metasomatized mantle. Presence of hornblende phenocryst in both gabbros and hornblendites indicates that the cumulates were produced from hydrous basalts through crystallization. The granitic rocks have adakite-like compositional characteristics, i.e., high Sr/Y ratios but low Y contents, which were formed by melting of a thickened lower crust. Zircons from six samples, including a volcanic rock (an andesite), three cumulates (a hornblendites, a hornblende-bearing gabbro and a gabbro) and two granitic (a tonalite and a granodiorite) rocks, have been dated to yield identical ages of ∼155–160 Ma. This suggests that the volcanic eruption and plutonic emplacement were coevally developed in the Zedong terrane. Zircons from both the andesite and the cumulates have similar positive εHf(t) values (∼+11.6 to +16.7), indicating they were stemmed from similarly depleted mantle sources. Meanwhile, zircons from the granitic rocks also have positive εHf(t) values of ∼+12.6 to +15.2, implying their derivation from a juvenile lower crust. Therefore, we proposed that the basalts in the Zedong terrane were formed through partial melting of the mantle wedge metasomatized by slab-released fluids/melts. A part of hydrous basalts were underplated in the thickened lower crust beneath the Zedong terrane, which gave rise to the cumulate and granitic rocks. By comparison, magmatic rocks in the Zedong terrane show compositional similarities with the Jurassic rocks exposed in the Gangdese arc. This suggests that the Zedong terrane represents a slice of the active continental margin developed on the southern margin of the Lhasa terrane as a result of the northward subduction of the Neo-Tethys Ocean during the Late Jurassic, rather than the vestige of an intra-oceanic arc. 相似文献
572.
新华铅锌(银)矿床位于钦杭成矿带南端云开地区的六万大山隆起区,是以铅锌为主的含银热液脉型多金属矿床。矿体赋存在含堇青石黑云母花岗岩中,主要呈脉状和透镜状产出。文章利用激光阶段加热技术对与矿化密切共生的白云母进行Ar-Ar年龄测定。结果表明,新华铅锌(银)多金属矿床的~(40)Ar/~(39)Ar坪年龄为(165.3±1.6)Ma(MSWD=0.38),反等时线年龄为(165.2±1.6)Ma(MSWD=0.42),等时线年龄和坪年龄一致,代表了白云母的冷却年龄和矿床的形成年龄,表明该矿床的形成与云开地区燕山早期的岩浆活动有关,这与区域成矿事件相吻合。结合前人对华南地区地球动力学背景的研究成果,初步认为新华铅锌(银)矿床形成于中-晚侏罗世碰撞板块边缘再次活化,岩石圈伸展的构造背景。 相似文献
573.
苏鲁超高压变质带东北端多种成因类型变基性岩:来自岩石学、同位素年代学及地球化学属性的制约 总被引：2，自引：2，他引：0
苏鲁超高压变质带是扬子板块与华北板块在三叠纪俯冲-碰撞的产物。变基性岩是苏鲁超高压变质带内出露最广泛的岩石类型之一,研究其岩石学、年代学、地球化学属性及成因机制,对于揭示扬子板块与华北板块之间的俯冲-碰撞-折返的动力学过程具有重要的科学意义。以(退变)榴辉岩为代表的超高压变质岩石广泛出露在威海-荣成一带,少量出露在乳山地区。锆石LA-ICP-MS U-Pb定年结果显示,(退变)榴辉岩的原岩时代为792~760Ma,峰期榴辉岩相变质时代为243~226Ma,后期角闪岩相退变质时代为221~207Ma。非榴辉岩相变质的基性岩(麻粒岩和斜长角闪岩)主要出露在乳山地区,其原岩形成时代应不晚于古元古代(1939Ma),峰期麻粒岩相变质时代为1895~1870Ma,后期角闪岩相退变质时代为1848~1806Ma,与胶北地体变基性岩的原岩时代和变质时代十分相似。全岩地球化学研究结果表明,(退变)榴辉岩的原岩显示高Fe拉斑玄武岩的特点,根据其稀土和微量元素特征,可将(退变)榴辉岩进一步划分为A、B和C三组。在球粒陨石标准化稀土配分模式和原始地幔均一化蛛网图解上,A、B和C三组样品分别具有轻稀土弱亏损、轻稀土弱富集和轻稀土富集的特点。轻稀土富集或弱富集型(退变)榴辉岩的原岩地球化学性质与岛弧或大陆玄武岩相似,它们的源区可能与深部富集地幔或受流体交代的地幔楔存在密切的成因关系;而轻稀土亏损型(退变)榴辉岩的原岩可能来自于亏损地幔的部分熔融。由此可见,(退变)榴辉岩的原岩具有成因多样性的特点。乳山地区的基性麻粒岩和斜长角闪岩的原岩也具有高Fe拉斑玄武岩的地球化学属性,Al2O3与Mg O呈正相关变化,TiO_2、P_2O_5与MgO表现出一定程度的负相关性。绝大多数非榴辉岩相变质基性岩的球粒陨石标准化稀土配分模式和原始地幔均一化蛛网配分曲线具有微右倾或明显右倾的特点。上述特征表明,研究区绝大多数非榴辉岩相变质的基性岩原岩来自于富集地幔,少数来自于原始地幔或亏损地幔,并经历了斜长石和辉石的分离结晶以及不同程度的部分熔融过程。由此可见,乳山地区出露的非超高压变质基性岩的原岩具有与胶北地体(高压)基性麻粒岩相近的成因特点。岩石学、同位素年代学和地球化学特征的综合对比研究结果表明,在苏鲁超高压变质带东北端的威海-荣成-乳山地区,既存在与华北板块古老变质基底相关的变基性岩,也存在与华南板块北缘新元古代变质基底相关的超高压榴辉岩,表明三叠纪时期华北板块东南缘胶北地体的部分古老变质基底曾卷入到扬子板块与华北板块之间的俯冲-碰撞造山过程,随后与超高压岩石一起抬升折返,形成当今的构造混杂岩带。 相似文献
574.
575.
576.
577.
GUO Fuxiang Research Centre of Prediction of Hidden Ore Deposits Guilin Institute of Technology Guilin 《《地质学报》英文版》2000,74(1):1-6
The Kazakhstanian plate was near the Tarim, Sino-Korean and South China-Southeast Asian plates in the Middle-Late Cambrian and Late Ordovician, and approached the Siberian plate in the other periods of the Early Palaeozoic. The Hi and Toksun-Yamansu terranes had been split from the Tarim plate before the Middle Devonian and then went close to Angaraland in the late Early Permian. The Beishan area on the northeastern margin of the Tarim plate came close to Angaraland first in the early Early Permian. The suturing age between the Tarim and Ka-zakhstanian-Siberian plates is generally the same as that between the Turkey-Central Iran-Gangdise and South China-Southeast Asian plates. The suturing event took place in the early Early Permian, while the corresponding tectogeny occurred between the Early and Late Permian. 相似文献
578.