The morphotectonics and its evolutionary dynamics of the central Southwest Indian Ridge (49° to 51°E)

The morphotectonic features and their evolution of the central Southwest Indian Ridge （SWIR） are dis- cussed on the base of the high-resolution flfll-coverage bathyraetric data on the ridge between 49°-51°E. A comparative analysis of the topographic features of the axial and flank area indicates that the axial topogra- phy is alternated by the ridge and trough with en echelon pattern and evolved under a spatial-temporal mi- gration especially in 49°-50.17°E. It is probably due to the undulation at the top of the mantle asthenosphere, which is propagating with the mantle flow. From 50.17° to 50.7°E, is a topographical high terrain with a crust much thicker than the global average of the oceanic crust thickness. Its origin should be independent of the spreading mechanism of ultra-slow spreading ridges. The large numbers of volcanoes in this area indicate robust magmatic activity and may be related to the Crozet hot spot according to RMBA （residual mantle Bouguer anomaly）. The different geomorphological feature between the north and south flanks of the ridge indicates an asymmetric spreading, and leading to the development of the OCC （oceanic core complex）. The tectonic activity of the south frank is stronger than the north and is favorable to develop the OCC. The first found active hydrothermal vent in the SWIR at 37°47＇S, 49°39＇E is thought to be associated with the detach- ment fault related to the OCC.

Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates

Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.

从“谋求和平”到“坚决抵抗”——抗战胜利后延安《解放日报》社论的反内战宣传研究

抗战胜利后至解放战争爆发的短暂总体和平时期,国共双方围绕“战后和平”这一议题展开了激烈的宣传交锋。作为中共中央机关报,延安《解放日报》以社论为核心渠道,向国内民众传达了中国共产党“和平民主团结”的基本方针,有力地反击了国民党对内战责任问题的宣传攻势。在以往研究中,关于抗战胜利后国共两党之宣传交锋已有大量详尽论述,但对于这一时间段内两党反内战宣传的变化过程与用意则关注较少。本文以抗战胜利后延安《解放日报》发表的社论为主要研究对象,讨论其在反内战主题宣传上如何展开与结束,及其在宣传斗争与舆论引导上所体现出的特点。

Zr-Cr-Fe合金马氏体相变过程中三变体团簇的择优形成及其晶体学分析（英文）

采用ECC, TEM和EBSD表征技术,研究了Zr-Cr-Fe合金经β相淬火后的马氏体组织特征。结果表明:马氏体相变过程中,任一高温β相都能够转变为12个α马氏体变体。而这12个α马氏体变体并不是随机分布的,而是择优形成了4个亚区域。每一个亚区域由一种三变体团簇组成,而该三变体团簇表现为典型的三角形自我协调形貌。进一步晶体学分析表明:组成每一个团簇的这3个马氏体变体与母相之间存在一个共同的<111>β极点,同时该三变体相互之间的取向关系为60°/<1120>。由于在β→α马氏体相变过程中存在形状应变,而三变体团簇的形成能够最大程度的协调该应变。