全文获取类型
收费全文 | 29篇 |
免费 | 2篇 |
国内免费 | 6篇 |
专业分类
大气科学 | 2篇 |
地球物理 | 2篇 |
地质学 | 27篇 |
海洋学 | 1篇 |
天文学 | 2篇 |
自然地理 | 3篇 |
出版年
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有37条查询结果,搜索用时 15 毫秒
11.
Dwijesh RAY Sridhar D. IYER Ranadip BANERJEE Saumitra MISRA M. WIDDOWSON 《《地质学报》英文版》2007,81(1):99-112
1 Introduction The Northern Central Indian Ridge (NCIR) between 3° and 11°S latitudes is joined to the north with the slow spreading Carlsberg Ridge (CR; ~24–26 mm/a, full spreading rate) and to the south with the intermediate spreading Southern Central Indian Ridge (SCIR; ~50 mm/ a) (Fig. 1). Earlier petrological investigations of the Central Indian Ridge were concentrated either on or along the CR to the north and at the southern end of the CIR up to the Rodriguez Triple Junc… 相似文献
12.
13.
14.
Abstract Daily flow records, rainfall data and tropical cyclone maps during 1970–1998 are used to document the impact of tropical cyclones (TCs) on floods in the Rewa River system, Viti Levu, Fiji. Floods are large, brief, isolated events caused by TCs and non-TC tropical rainstorms. More floods are caused by tropical rainstorms than by TCs, but TC floods are larger. The log Pearson Type III distribution consistently provided the best fit to partial duration flood series and the widely-recommended generalized Pareto distribution performed very poorly, underscoring the need to test a variety of distributions for a particular geographic location. Tropical cyclones occur more often in Fiji during negative values of the Southern Oscillation Index (SOI) and all TCs that occurred during El Niño conditions caused floods. Peak flood discharges caused by TCs are inversely correlated with the SOI, reflecting possible links with tropical cyclone frequency and precipitation intensity. 相似文献
15.
Dwijesh RAY Ranadip BANERJEE Sridhar D IYER Basavaraju BASAVALINGU Subir MUKHOPADHYAY 《《地质学报》英文版》2009,83(6):1122-1135
Abstract: The glass and mineral chemistry of basalts examined from the northern central Indian ridge (NCIR) provides an insight into magma genesis around the vicinity of two transform faults: Vityaz (VT) and Vema (VM). The studied mid-ocean ridge basalts (MORBs) from the outer ridge flank (VT area) and a near-ridge seamount (VM area) reveal that they are moderately phyric plagioclase basalts composed of plagioclase (phenocryst [An60–90] and groundmass [An35–79]), olivine (Fo81–88), diopside (Wo45–51, En25–37, Fs14–24), and titanomagnetite (FeOt ~63.75 wt% and TiO2 ~22.69 wt%). The whole-rock composition of these basalts has similar Mg# [mole Mg/mole(Mg+Fe2+)] (VT basalt: ~0.56–0.58; VM basalt: ~0.57), but differ in their total alkali content (VT basalt: ~2.65; VM basalt: ~3.24). The bulk composition of the magma was gradually depleted in MgO and enriched in FeOt, TiO2, P2O5, and Na2O with progressive fractionation, the basalts were gradually enriched in Y and Zr and depleted in Ni and Cr. In addition, the SREE of magma also increased with fractionation, without any change in the (La/Yb)N value. Glass from the VM seamount shows more fractionated characters (Mg#: 0.56–0.57) compared to the outer ridge flank lava of the VT area (Mg#: 0.63–0.65). This study concludes that present basalts experienced low-pressure crystallization at a relatively shallow depth. The geochemical changes in the NCIR magmas resulted from fractional crystallization at a shallow depth. As a consequence, spinel was the first mineral to crystallize at a pressure >10 kbar, followed by Fe-rich olivine at <10 kbar pressure. 相似文献
16.
Abstract— The ages of seven rock fragments from the soil fraction of the Luna 24 core have been determined using a laser 40Ar-39Ar stepped heating technique. The investigated lithologies include fragments of fine-grained ophitic basalt, coarse-grained basalt, metabasalts and a regolith breccia. Most of the samples contain nonradiogenic Ar components of variable 36Ar/40Ar composition. These surface-correlated trapped components are predominantly released at low temperature and can be distinguished from volume-correlated radiogenic and cosmogenic components released at higher temperature during stepped heating. Binary mixtures of radiogenic and cosmogenic Ar components give linear correlations on 36Art/40Ar-39Ar/40Ar diagrams from which the age and 36Ar/40Ar value of trapped Ar can be determined. The ages obtained span a narrow range between 3.18-3.28 Ga with an average of 3.22 ± 0.04 Ga. This is interpreted as being the age of the basalts at the Luna 24 sampling site. Systematic age differences between lithologies were not detected; however, a single age of 2.93 Ga obtained from a coarse-grained basalt hints at the possibility of younger volcanism. The results of this work effectively triple the chronological information available for Mare Crisium and are within the range of radiometric age measurements of Luna 24 mare basalts obtained previously. 相似文献
17.
ADITI MANDAL ARIJIT RAY MAYUKHEE DEBNATH SANKAR PRASAD PAUL 《Journal of Earth System Science》2012,121(3):793-812
18.
19.
Andesite and dacite from Barren and Narcondam volcanic islands of Andaman subduction zone are composed of plagioclase, orthopyroxene,
clinopyroxene, olivine, titanomagnetite, magnesio-hornblende and rare quartz grains. In this study, we use the results of
mineral chemical analyses of the calc-alkaline rock suite of rocks as proxies for magma mixing and mingling processes. Plagioclase,
the most dominant mineral, shows zoning which includes oscillatory, patchy, multiple and repetitive zonation and ‘fritted’
or ‘sieve’ textures. Zoning patterns in plagioclase phenocrysts and abrupt fluctuations in An content record different melt
conditions in a dynamic magma chamber. ‘Fritted’ zones (An55) are frequently overgrown by thin calcic (An72) plagioclase rims over well-developed dissolution surfaces. These features have probably resulted from mixing of a more silicic
magma with the host andesite. Olivine and orthopyroxene with reaction and overgrowth rims (corona) suggest magma mixing processes.
We conclude that hybrid magma formed from the mixing of mafic and felsic magma by two-stage processes – initial intrusion
of hotter mafic melt (andesitic) followed by cooler acidic melt at later stage. 相似文献
20.
WILLIAM R. NORMARK† CHARLES K. PAULL‡ DAVID W. CARESS‡ WILLIAM USSLER III‡ RAY SLITER 《Sedimentology》2009,56(6):1690-1704
Erosional and depositional bedforms have been imaged at outcrop scale in the upper Redondo Fan, in the San Pedro Basin of offshore Southern California in ≥600 m water depths, using an Autonomous Underwater Vehicle developed by the Monterey Bay Aquarium Research Institute. The Autonomous Underwater Vehicle is equipped with multibeam and chirp sub-bottom sonars. Sampling and photographic images using the Monterey Bay Aquarium Research Institute Remotely Operated Vehicle Tiburon provide groundtruth for the Autonomous Underwater Vehicle survey. The 0·3 m vertical and 1·5 m lateral bathymetric resolution and 0·1 m sub-bottom profile resolution provide unprecedented detail of bedform morphology and structure. Multiple channels within the Redondo Fan have been active at different times during the Late Holocene (0 to 3000 yr bp ). The currently active channel extending from Redondo Canyon makes an abrupt 90° turn at the canyon mouth before resuming a south-easterly course along the east side of the Redondo Fan. This channel is floored by sand and characterized by small steps generally <1 m in relief, spaced 10 to 80 m in the down-channel direction. A broader channel complex lies along the western side of the fan valley that was last active more than 850 years ago. Two distinct trains of large scours, with widths ranging from tens to a few hundred metres and depths of 20 m, occur on the floor of the western channel complex, which has a thin mud drape. If observed in cross-section only, these large scours would probably be misidentified as the thalweg of an active channel. 相似文献