Analysis of Altimeter Wet Troposphere Range Correction   总被引：2，自引：0，他引：2  

纪永刚张杰  姬光荣 《中国海洋湖沼学报》2004,22(2):150-156

Wet path delay caused by tropospheric water vapor must be considered before altimeter data are used in oceanic application. This paper analyzed several methods of atmosphere water range correction (AWRC) using Seasat,Geosat, TOPEX and ERS-1 data, especially the calculated delay path using brightness temperature of TMR on TOPEX and EMR on ERS-1 ; and discussed some other problems of AWRC.  相似文献   

P–T evolution of glaucophane–omphacite bearing HP–LT rocks in the western Tianshan Orogen, NW China:new evidence for 'Alpine-type' tectonics     

R. Klemd  F. C. Schröter  T. M. Will  J. Gao 《Journal of Metamorphic Geology》2002,20(2):239-254

The late Palaeozoic western Tianshan high‐pressure /low‐temperature belt extends for about 200 km along the south‐central Tianshan suture zone and is composed mainly of blueschist, eclogite and epidote amphibolite/greenschist facies rocks. P–T conditions of mafic garnet omphacite and garnet–omphacite blueschist, which are interlayered with eclogite, were investigated in order to establish an exhumation path for these high‐pressure rocks. Maximum pressure conditions are represented by the assemblage garnet–omphacite–paragonite–phengite–glaucophane–quartz–rutile. Estimated maximum pressures range between 18 and 21 kbar at temperatures between 490 and 570 °C. Decompression caused the destabilization of omphacite, garnet and glaucophane to albite, Ca‐amphibole and chlorite. The post‐eclogite facies metamorphic conditions between 9 and 14 kbar at 480–570 °C suggest an almost isothermal decompression from eclogite to epidote–amphibolite facies conditions. Prograde growth zoning and mineral inclusions in garnet as well as post‐eclogite facies conditions are evidence for a clockwise P–T path. Analysis of phase diagrams constrains the P–T path to more or less isothermal cooling which is well corroborated by the results of geothermobarometry and mineral textures. This implies that the high‐pressure rocks from the western Tianshan Orogen formed in a tectonic regime similar to ‘Alpine‐type’ tectonics. This contradicts previous models which favour ‘Franciscan‐type’ tectonics for the southern Tianshan high‐pressure rocks.  相似文献   

同步卫星伪码测距系统设计     

韩学义  张挥 《时间频率学报》1993,16(1):20-31

根据伪码测距技术和卫星通讯的特点,针对我国已发射的或将要发射的以及我国目前租用的C波段和Ku波段卫星,设计了用高精密传输终端(或MITREX)进行伪码测距时卫星地面站的参数,并估算出了伪码测距精度。  相似文献   

逐步线性回归法实现中华虎头蟹(Orithyia sinica) 形态指标与体重的通径分析   总被引：2，自引：0，他引：2  

来守敏  王仁杰  姜令绪  秦浩  李玉全 《海洋与湖沼》2015,46(6):1438-1443

为探讨中华虎头蟹(Orithyia sinica)形态指标与体重的关系, 为良种选育提供最佳的测量指 标, 实验以中华虎头蟹为材料, 测量甲宽、甲长、眼间距、侧齿间距、大螯不动指长、大螯宽、步足 长节长、体高、体重等26 个指标, 借助逐步线性回归、相关分析和通径分析等方法, 分析形态指标 与体重的关系。结果表明, 除第Ⅳ侧齿间距(A₈)外, 实验所测形态指标与体重的相关系数均达到了显 著水平(P<0.05); 采用逐步线性回归的方法建立了多元回归方程Y=-273.841+10.4X₁+2.867X₂, 其中 Y 为体重(g), X₁ 为右大螯宽(mm), X₂ 为第Ⅱ侧齿间距(mm), 定量分析了形态指标对体重的影响结果。  相似文献   

An automated method for the calculation of P–T paths from garnet zoning,with application to metapelitic schist from the Kootenay Arc,British Columbia,Canada     

D. P. Moynihan  D. R. M. Pattison 《Journal of Metamorphic Geology》2013,31(5):525-548

An automated method for the calculation of P–T paths based on garnet zoning is presented and used to interpret zoning in metapelitic schist from the southern Canadian Cordillera. The approach adopted to reconstruct the P–T path is to match garnet compositions along a radial transect with predictions from thermodynamic forward models, while iteratively modifying the composition to account for fractional crystallization. The method is applied to a representative sample of garnet‐ and staurolite‐bearing schist from an amphibolite facies Barrovian belt in the southern Canadian Omineca belt. Garnet zoning in these schists is concentric and largely continuous from core to rim. Three zones are present, the first two of which coincide with sector‐zoned cores of garnet crystals. Similar zoning is developed in rocks that contain or lack staurolite, respectively, suggesting garnet growth was restricted to the initial part of the prograde P–T path prior to the development of staurolite. Growth zoning in large garnet crystals has not been significantly modified by diffusion. This interpretation is based on zoning characteristics of garnet crystals and is further supported by results of a forward model incorporating the effects of simultaneous fractional crystallization and intracrystalline diffusion. The P–T path calculated for this rock includes an initial, linear stage with a high dP/dT, and a later stage dominated by heating. The approach adopted in this study may have application to other garnet‐bearing rocks in which growth zoning is preserved.  相似文献   

P–T path of high-pressure/low-temperature rocks and tectonic implications in the western Tianshan Mountains, NW China     

Gao  Klemd  Zhang  Wang  & Xiao 《Journal of Metamorphic Geology》1999,17(6):621-636

The Chinese western Tianshan high-pressure/low-temperature (HP–LT) metamorphic belt, which extends for about 200 km along the South Central Tianshan suture zone, is composed of mainly metabasic blueschists, eclogites and greenschist facies rocks. The metabasic blueschists occur as small discrete blocks, lenses, bands, laminae or thick beds in meta-sedimentary greenschist facies country rocks. Eclogites are intercalated within blueschist layers as lenses, laminae, thick beds or large massive blocks (up to 2 km² in plan view). Metabasic blueschists consist of mainly garnet, sodic amphibole, phengite, paragonite, clinozoisite, epidote, chlorite, albite, accessory titanite and ilmenite. Eclogites are predominantly composed of garnet, omphacite, sodic–calcic amphibole, clinozoisite, phengite, paragonite, quartz with accessory minerals such as rutile, titanite, ilmenite, calcite and apatite. Garnet in eclogite has a composition of 53–79 mol% almandine, 8.5–30 mol% grossular, 5–24 mol% pyrope and 0.6–13 mol% spessartine. Garnet in blueschists shows similar composition. Sodic amphiboles include glaucophane, ferro-glaucophane and crossite, whereas the sodic–calcic amphiboles mainly comprise barroisite and winchite. The jadeite content of omphacite varies from 35–54 mol%. Peak eclogite facies temperatures are estimated as 480–580 °C for a pressure range of 14–21 kbar. The conditions of pre-peak, epidote–blueschist facies metamorphism are estimated to be 350–450 °C and 8–12 kbar. All rock types have experienced a clockwise P–T path through pre-peak lawsonite/epidote-blueschist to eclogite facies conditions. The retrograde part of the P–T path is represented by the transition of epidote-blueschist to greenschist facies conditions. The P–T path indicates that the high-pressure rocks formed in a B-type subduction zone along the northern margin of the Palaeozoic South Tianshan ocean between the Tarim and Yili-central Tianshan plates.  相似文献   

Mineral isograds and metamorphic zones of the Anglesey blueschist belt, UK: implications for the metamorphic development of a Neoproterozoic subduction–accretion complex     

T. KAWAI  B. F. WINDLEY  M. TERABAYASHI  H. YAMAMOTO  S. MARUYAMA  Y. ISOZAKI 《Journal of Metamorphic Geology》2006,24(7):591-602

The 560–550 Ma blueschists and associated rocks in Anglesey, UK were derived from a subduction–accretion complex. The blueschist unit is divided into three mineral zones by two newly mapped metamorphic isograds; zone I sub-greenschist facies, (crossite isograd), zone II blueschist facies, (barroisite isograd), zone III epidote-amphibolite facies. The zones and isograds dip gently to the east, and decrease in metamorphic grade from the central high-pressure zone III to lower grade zones II and I to the west and east. The P – T conditions estimated from zoned amphibole indicate an anticlockwise P – T path following adjustment to a cold geotherm. This path is well preserved in the compositional zoning of Na–Ca amphibole that have a core of barroisite surrounded by a rim of crossite, although this is only locally developed. The sense of subduction was to the east and exhumation to the west, as indicated by the metamorphic isograds. The symmetrical arrangement of the metamorphic zones with the deepest high-pressure rocks in the middle suggests an isoclinal antiformal structure that formed by wedge extrusion during exhumation in the subduction zone.  相似文献   

Temperature–time path for the low-pressure Ryoke metamorphism, Japan, based on chemical zoning in garnet     

T. OKUDAIRA 《Journal of Metamorphic Geology》1996,14(4):427-440

Garnet crystals from low-pressure/high-temperature (LPHT) Ryoke metamorphic rocks in the Yanai district, south-western Japan, show several kinds of chemical zoning patterns that systematically vary with grain radius between c . 0.1 and 0.5  mm. Large grains (> c . 0.4  mm) show normal zoning and small grains (< c . 0.4  mm) show unzoned or reversely zoned cores. Observations of the chemical zoning and of the spatial and size distributions of the garnet grains between c . 0.1 and 0.5  mm in radius suggest that they were formed by continuous nucleation and diffusion-controlled growth.
A previously estimated temperature–time path ( T  – t path) for the Ryoke metamorphism, using 1-D numerical simulation, is characterized by a rapid increase in temperature, 0.0017  °C yr⁻¹ on average, and a period of high temperature (>600  °C) shorter than 0.5 Myr, which was presumably caused by the intrusion of a granodiorite sheet. Chemical zoning of garnet grains with different radii simulated for the T  – t path using a numerical model of continuous nucleation and diffusion-controlled growth, in combination with intracrystalline diffusion, compares well with the observed zoning patterns in garnet grains with different radii. This is in spite of the fact that the simulated zoning patterns vary greatly, depending on subtle differences in the T–t history. Therefore, they suggest that the T–t path gives a good explanation for the LPHT Ryoke metamorphism. Although this study only refers to the Ryoke metamorphism, the technique may be applicable to thermal modelling of other metamorphic terranes.  相似文献   

变质岩的变质序列分析——以辽河群为例(续)     

郭洪方 《国土资源》1999,(3)

辽河群是出露于辽宁省东部的独具特色的早元古代变质岩系，赋存丰富的矿产资源。变质岩系遭受了中浅变质作用，经历了三幕变形，它们同是吕梁造山作用的组成部分。在二者的共同作用下，于１ ９００ Ｍａ 使辽河群固结硬化为结晶基底。辽河群有三幕变形，但对应的热事件仅有一期。研究表明，变质矿物的结晶时间与变质带密切相关，就一种变质矿物而言，于不同的变质带中不仅首次晶出的时间不同，并且结晶结束的时间也不同，即表明不同的变质带具有不同的ＰＴｔ 轨迹。  相似文献   

A polycyclic two-stage corona growth in the Iforas Granulitic Unit (Mali)   总被引：2，自引：0，他引：2  

A.-M. BOULLIER  P. BARBEY 《Journal of Metamorphic Geology》1988,6(2):235-254

Abstract Retrograde and prograde mineral assemblages from metapelitic and metabasic rocks of the Iforas Granulitic Unit (Mali) were generated by the superimposition of two granulite facies metamorphic events. They clearly result from a polycyclic evolution and can be related to a late Eburnean unroofing followed by a Pan-African burial.
Thermobarometry on Pan-African garnet-bearing assemblages yields ( P, T ) estimates of 620±50°C and 5± Ikbar. The nearly anhydrous conditions produced in the Eburnean appear to be the direct cause of the unusually lowtemperature granulite-facies metamorphism in the Pan-African. These P, T estimates are compared with those obtained on the underlying unit (Kidal Assemblage) upon which the Iforas Granulitic Unit was thrust. A P-T-t path, during the Pan-African orogeny, is proposed and discussed for both the Iforas Granulites and Kidal Assemblage.  相似文献