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21.
西秦岭北带泥盆系舒家坝组深海陆源碎屑沉积序列的研究 总被引:6,自引:4,他引:2
西秦岭北带泥盆系舒家坝组属中晚泥盆世,地层总厚超过2000m。除最上部碳酸盐岩段外,主要是细、粉砂岩与页(泥)岩不等厚五层组成的沉积序列。本文从以下三个方面论证该序列形成于半深海-深海环境:1)时空上主要是由分布稳定的细粒浊积岩组成;2)等深积岩与浊积岩相伴而生;3)在浊积岩系和深海泥页岩中发现了高分异度、高丰度的遗迹化石共41个属,其中占遗迹总属的80%为深水型分子。此外,从岩相、垂直序列和古水流三方面的特征论证了舒家坝组属非扇沉积模式。 相似文献
22.
Ray equation migration of wide-angle reflections in 2-D medium is one kind of Kirchhoff prestack depth migration method. Based
on ray theory, this method can be used extensively in 2-D inhomogeneous medium, and shows its advantage in wide-angle reflection
study. After calculating ray fields, we can get the wave fields of sources and receivers by interpolation, and the intensity
(or amplitude) A
p
corresponding to the depth point P at travel-time t
P
=t
SP
+t
PR
can be found in seismograms. Ray equation migration is completed by transforming A
P
according to the specific relation, migrating it to the depth point, then calculating the ray fields of lots of sources and
receivers in the same way and finally stacking the outcomes. Numerical calculation has yielded satisfactory results. Data
processing of the Zhuangmu-Yuexi-Huangmei-Zhanggondu profile passing through the Dabie orogenic zone provides a structural
form of M-discontinuity along the profile. The result shows that the high pressure metamorphic rock zone of South Dabie rock
mass is related to the uplifting of M-discontinuity here. "Mountain root" exists under North Dabie rock mass, which conforms
with gravity isostasy theory. The Xiaotian-Mozitan fault is a suture zone as a result of the collision of North China plate
with Yangtze plate, and extends through M-discontinuity. The abyssal fault near Liu’an is the extended eastern section of
the Luonan-Minggang fault, which is also confirmed here.
Contribution No. RCEG 96012, Research Center of Exploration Geophysics, SSB, China.
This project was supported by the National Natural Science Foundation of China and the Chinese Joint Seismological Science
Foundation. 相似文献
23.
24.
宫同伦 《地球科学与环境学报》1996,(4)
目前,对小秦岭金矿的成因有三种观点:岩浆热液、变质热液和大气降水热液,这三种观点均有许多难以解释的地质现象。这些矛盾的出现表明,可能有另种矿床成因的存在。笔者在此提出了由上地幔或下地壳物质向深断裂带排气液作用形成的"深源热液"新观点。该观点能很好地解决上述观点难以解决的地质问题。 相似文献
25.
Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with the δ18O-based age, it is suggested that ash Layer A is correlated to the youngest Toba tuff(YTT), Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic eruption event. 相似文献
26.
Mantle melting beneath the Southwest Indian Ridge: signals from clinopyroxene in abyssal peridotites
WANG Wei CHU Fengyou ZHU Jihao DONG Yanhui YU Xing CHEN Ling LI Zhenggang 《海洋学报(英文版)》2013,32(12):50-59
The mineral chemistry and texture of clinopyroxenes in peridotite from the Kingkong tectonic zone of the Southwest Indian Ridge segment in an effort to constrain mantle melting beneath this slow-spreading ridge are reported. There are three types of clinopyroxenes in the abyssal peridotites: coarse-grained, intergranu- lar and exsolved. The compositional variations among these three types suggest that the coarse-grained clinopyroxene is a mantle-derived source. The A1, Na and Ti contents and the Na/Ti ratio of the coarse- grained clinopyroxene may be used to monitor the degree of partial melting, combined with the contradis- tinction with Spinel Cr#, which is calculated to be between 7.9% and 14.9%, and may represent low degrees of melting in the global ocean ridge system. The along-axis compositional variations in the coarse-grained clinopyroxene suggest that the degree of partial melting is primarily controlled by the transform faults on both sides of the ridge. Nonetheless, the northwestern side of the ridge may be affected by a hypothesised detachment fault as documented by the calculated P-T conditions. Simultaneously high Na and low Ti con- tents in the coarse-grained clinoovroxene points to mantle heterogeneities along the ridge axis. 相似文献
27.
28.
29.
山东玲珑金矿田控矿断裂地球化学的初步研究 总被引:2,自引:0,他引:2
本文通过山东玲珑金矿田主要控矿断裂破碎带、断裂充填物(岩、矿脉)及其围岩(碎裂状花岗岩)的构造地球化学的初步研究,探讨了构造—岩浆—成矿的时、空、成因联系。研究结果表明:玲珑金矿田脉金矿床的形成与深断裂的多次活动、深熔岩浆的半原地上侵以及深源成矿物质的活化转移密切相关。 相似文献
30.
Gordon E. Swaters 《地球物理与天体物理流体动力学》2017,111(2):91-114
It is known that dissipative adjustment must occur in the cross-equatorial dynamics of a deep western boundary current (DWBC) that is in planetary-geostrophic balance away from the equator. Theoretical modelling and numerical simulations suggest that the dissipative zones correspond to “small” isolated zonally-elongated regions within the trough and crest of a nonlinear stationary equatorial planetary wave that is formed as the DWBC flows eastward along the equator. An internal frictional boundary layer theory is advanced to describe the leading order structure of the DWBC in the dissipative regions, which asymptotically matches with the large scale inviscid flow characteristics in the equatorial region. 相似文献