Seismic moment distribution   总被引：1，自引：0，他引：1  

Y. Y. Kagan 《Geophysical Journal International》1991,106(1):123-134

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Stellar Populations in Bulges of Spiral Galaxies     

Pascale Jablonka  Javier Gorgas  Paul Goudfrooij 《Astrophysics and Space Science》2002,281(1-2):367-370

We present a few results of a work in progress tackling the radial spectroscopic properties of bulges of spiral galaxies. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

A bimodal four‐parameter lognormal linear model of soil water repellency persistence     

C. M. Regalado  A. Ritter 《水文研究》2009,23(6):881-892

Soil water repellency may be characterized in terms of the delayed infiltration time of a water droplet resting on the soil surface, which is, water drop penetration time (WDPT), or repellency persistence. Such repellency persistence varies nonlinearly with soil water content (θ_g), although no models have been proposed to reproduce the variation of WDPT with θ_g in soils. Dynamic factor analysis (DFA) is used to identify two common patterns of unexplained variability in a scattered dataset of WDPT versus θ_g measurements. A four‐parameter lognormal distribution was fitted to both common patterns obtained by DFA, and these were combined additively in a weighted multiple linear bimodal model. We show how such an empirical model is capable of reproducing a large variety of WDPT versus θ_g curve shapes (N = 80) both within a wide range of measured WDPTs (0–17 000 s) and for samples with organic matter content ranging from 21·7 to 80·6 g (100 g)^?1. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

集聚型空间点模式结构信息提取研究     

毛政元 《测绘学报》2007,36(2):181-186

空间点模式是一个2维离散点集,点集中的每一个元素代表地球表面一个点状目标的空间位置。当2维离散点集具有集聚特征时,称其为集聚型空间点模式,它与空间聚类、制图综合和空间分析的许多具体应用紧密相关。如何提取集聚型空间点模式的结构信息(集聚子群的个数和对应的集聚中心)是其中尚未彻底解决的问题。作者以几何概率为理论基础,提出测度正方形区域内2维离散点集分布特征的H函数并推导其解析表达式,运用H函数设计和实现了集聚型2维离散点集结构信息提取的通用算法。利用该算法处理一个由居民地坐标数据得到的具有集聚特征的空间点模式,提取出其结构信息并进行可视表达。分别以该空间点模式中的各离散点为顶点和发生元生成Delaunay三角网和Voronoi图,在Delaunay三角网中保留面积最小的前1/10、前1/100三角形的顶点,在Voronoi图中保留面积最小的前1/10、前1/100邻近多边形的发生元,将可视表达的点集结构信息分别与依据Delaunay三角网和Voronoi图得到的结果进行对比分析。结果表明,运用H函数能够有效地提取出集聚型空间点模式的全局性结构信息,而Delaunay三角网和Voronoi图虽然能够反映其局部密度,但在提取全局结构信息时存在局限性。  相似文献   

Coherent Chemical Variation Trends of the 55-25 Ma Magmatic Rocks in SE Tibet:N-S Direction Lithospheric Stretching of Eurasia during Early Stage of India-Eurasia Collision     

YANG Tiannan  DONG Mengmeng  XUE Chuandong  XIN Di  LIANG Mingjuan 《《地质学报》英文版》2023,97(5):1283-1305

The progressive indentation of India into Eurasia generated an E–W-trending orthogonal collision belt and a N–S-trending oblique collision belt. Compiling available data reveals that ～70% of the Cenozoic igneous rocks in eastern and southeastern Tibet are concentrated within an ENE-trending, ～550-km long and ～250-km wide magmatic zone(CMZ) that once separated the orthogonal and oblique collision belts. The Latitude 26°N Line is now its southern boundary. The onset timing of magmatism of the CMZ ...  相似文献   

青藏高原古近系牛堡组三段天文周期旋回分析及古湖平面演化研究：以尼玛盆地尼1井为例          下载免费PDF全文

陈云  伊海生  陈璐洁  伍新和  唐闻强  汪锐  杨芸  张承志 《沉积与特提斯地质》2023,43(3):555-564

青藏高原中部尼玛盆地是一个形成于班公湖-怒江缝合带之上的新生代陆相裂谷盆地。交通不便和勘探程度较低等因素导致其高精度沉积旋回特征和地层学一直鲜有研究。尼1井是盆地内第一口地质探井,通过对该井古近系牛堡组三段的自然伽马测井曲线进行频谱分析,证实了天文轨道周期对盆地内湖相地层的沉积具有显著影响。滤波分析显示牛堡组三段保存了41个短偏心率(～100 kyr)周期,76个斜率(～54 kyr)周期和178个岁差(～23 kyr)周期,平均沉积速率为92.03m/Ma,沉积时限～4.1 Myr。此外,结合Fischer图解与总有机碳含量的变化趋势,确定牛堡组三段湖平面经历了1次长周期的升-降变化过程。综合分析,认为尼玛盆地优质烃源岩的形成主要受天文旋回周期影响下的湖平面变化所控制。  相似文献   

我国地质文化村（镇）空间分布特征及影响因素研究     

胡清清  杨晓霞 《地质论评》2023,69(4):2023040003-2023040003

地质文化村（镇）是地质文化科普的重要窗口,也是所在区域经济社会发展的重要依托,对其空间分布特征及影响因素的研究对我国地质文化村（镇）的进一步评定和可持续发展具有重要意义。运用最邻近指数、不平衡指数、核密度分析和地理探测器方法,对我国50个地质文化村（镇）的空间分布特征及其影响因素进行研究,研究表明：①地质文化村（镇）的空间分布类型为随机分布型;②各省（市、区）地质文化村（镇）数量差异明显,空间分布不均衡,呈“东多西少”格局;③地质文化村（镇）形成1个高密度核心区、2个次高密度集聚区、1条核心延长带;④影响我国地质文化村（镇）空间分布格局的因素由特色地质资源、自然条件以及社会经济与人文资源3个一级指标构成,其中社会经济与人文资源对地质文化村（镇）空间分布影响最大且效果显著。在今后地质文化村（镇）的评定建设中,应加强中西部地区地质文化村（镇）的建设和申报;适当给予中西部地区地质文化村（镇）评定倾斜;加大地质文化村（镇）宣传力度;充分发掘地质特色及民俗文化,加强地质文化村（镇）与文化的融合。  相似文献   

利用区域宽频地震数据反演2021年5月云南漾濞M_S6.4地震震源破裂过程     

朱音杰  罗艳  赵里  田建慧 《地球物理学报》2022,(3)

本文基于有限断层模型反演方法,利用区域宽频带数据反演了2021年5月云南漾濞M_S6.4地震的震源破裂过程,结果显示:此次地震的发震断层走向为SE向,主要以右旋走滑为主.破裂主要发生在震源东南侧,最大错动量约为0.55 m,位于深度约9 km处,发生明显破裂的深度约达13 km.此次地震释放的标量地震矩为1.48×10¹⁸N·m,相当于矩震级M_W6.05.地震能量主要在前11 s释放.在深度为6~8 km处破裂速度有明显的变快,可能加剧了地表的震动.  相似文献   

东南亚地震活动与b 值的时空分布特征     

王冠禾  刘绍文  祝文婧 《高校地质学报》2022,28(5):776-786

东南亚地区是“21世纪海上丝绸之路”（以下简称“海洋丝路”）的重要组成部分,该区历史上曾发生十余次巨大地震,地震及其次生地质灾害是威胁东南亚地区经济社会发展和国际合作的主要自然灾害。系统梳理该区地震活动的时空分布特征及评估未来灾害风险格局,对于推进“一带一路”倡议实施及区域经济社会可持续发展具有重要意义。文章基于东南亚地区1900年以来M≥5地震的时空分布统计分析和地震b值计算,揭示出该区的地震活动在时间上表现出活跃期与平静期交替变化的特征;空间上表现出明显的聚集效应,成丛性强且主要集中在5个地震统计区内,其中印尼—马来多岛弧盆系地震区和菲律宾群岛地震区的地震活动最为活跃。总体而言,东南亚5个地震区的b值偏低,在0.42~0.91之间。该区内的地震b值也存在时空差异,受大地震事件、俯冲带年龄、活动断裂带和震源深度等众多因素影响,但主控因素在不同区域有所不同。地震b值时空变化特征对区域地震活动预测具有启示作用。上述认识为推进“海洋丝路”工程建设和“一带一路”防灾减灾对策提供了科学支撑。  相似文献   

3D Modeling and Determination of Factors Responsible for Zinc-Lead Mineralization in the Mehdiabad Deposit, Central Iran, based on Statistical Analysis of Geochemical Data     

Zahra BONYADI 《《地质学报》英文版》2022,96(6):2040-2055

Although the Mehdiabad zinc-lead deposit is one of the most well-known deposits in the central Iran structural zone, the genesis of the deposit remains controversial. The host rock of the ore is a dolomitic limestone of the Lower Cretaceous Taft Formation. In the two main orebodies of the deposit, which includes the Black Hill and East Ridge ore zones, the oxide and sulfide ores are observed at the surface and at depth, respectively. The elements Zn, Fe, Mn and Mg are more abundant in the East Ridge ore zone (in both sulfide and oxide ores), with Ba, Pb, Ag and Cu being more abundant in the Black Hill oxide ore. Based on the distribution of elements and their correlation with each other in these ore zones, the elements are divided into three general groups, that of terrigenous elements, chemically-deposited elements and ore-forming (hydrothermally deposited) elements, a division that is supported by the results of factor analyses. The spatial distribution of elements is jointly affected by contact with host rocks, the boundary of oxide-sulfide ores and fault zones. The main factors governing the distribution of elements are the mechanical transfer of detrital sediments, chemical sedimentation, transfer by hydrothermal fluids, oxidation and surface dissolution, all of which affected the spatial distribution of elements. The ore-forming elements are mostly affected by hydrothermal fluids and oxidation. This study not only provides additional information about the genesis of the Mehdiabad deposit, but also could assist in the exploitation of ore and further exploration purposes. The results of this study can aid in the exploration and exploitation of the Mehdiabad deposit and similar deposits in the region.  相似文献