巴西卡拉加斯(Carajás)地区发育古老的太古宙变质基底,是世界上矿床类型最丰富、资源聚集程度最高的成矿区之一。在太古宙花岗岩-绿岩为主体的结晶基底中,含有大量紫苏花岗岩、奥长花岗岩-英云闪长岩-花岗闪长岩(trondhjemite-tona...巴西卡拉加斯(Carajás)地区发育古老的太古宙变质基底,是世界上矿床类型最丰富、资源聚集程度最高的成矿区之一。在太古宙花岗岩-绿岩为主体的结晶基底中,含有大量紫苏花岗岩、奥长花岗岩-英云闪长岩-花岗闪长岩(trondhjemite-tonalite-granodiorite,TTG)岩套和未完全解体的变质深成岩,目前对其认识仍存在较大分歧。岩浆岩的正确划分和精细研究是深入认识南美克拉通演化的重要手段,在调查卡拉加斯地区基底中变质侵入岩的基础上,结合前人资料将其进一步划分为中太古代的紫苏花岗岩、层状基性—超基性岩和TTG岩套,新太古代的基性—超基性杂岩、TTG岩套、同构造花岗岩、后构造花岗岩等,以及古元古代的碱性花岗岩。结合岩石学、地球化学和年代学方法综合分析了卡拉加斯地区的花岗质深成岩,锆石U-Pb测年获得的花岗岩^(207)Pb/^(206)Pb表面年龄集中在2899~2831 Ma、2742~2622 Ma和1919 Ma 3个时期,认为南美克拉通在经历了古太古代陆核形成、中太古代古大陆增生后,在太古宙末期和古元古代发生了二阶段的克拉通化过程,在中元古代—新元古代克拉通开始被破坏。通过对比南美克拉通与华北克拉通的早期演化过程,推测南美克拉通的构造演化早期受地幔柱控制,晚期转变为以板块构造为主导的大陆增生机制。研究有助于深入认识和对比矿集区成矿过程及其成矿效应。展开更多
Information on the spatial and temporal patterns of surface carbon flux is crucial to understanding of source/sink mechanisms and projection of future atmospheric CO2 concentrations and climate. This study presents th...Information on the spatial and temporal patterns of surface carbon flux is crucial to understanding of source/sink mechanisms and projection of future atmospheric CO2 concentrations and climate. This study presents the construction and implementation of a terrestrial carbon cycle data assimilation system based on a dynamic vegetation and terrestrial carbon model Vegetation-Global-Atmosphere-Soil(VEGAS) with an advanced assimilation algorithm, the local ensemble transform Kalman filter(LETKF, hereafter LETKF-VEGAS). An observing system simulation experiment(OSSE) framework was designed to evaluate the reliability of this system, and numerical experiments conducted by the OSSE using leaf area index(LAI) observations suggest that the LETKF-VEGAS can improve the estimations of leaf carbon pool and LAI significantly, with reduced root mean square errors and increased correlation coefficients with true values, as compared to a control run without assimilation. Furthermore, the LETKF-VEGAS has the potential to provide more accurate estimations of the net primary productivity(NPP) and carbon flux to atmosphere(CFta).展开更多
文摘巴西卡拉加斯(Carajás)地区发育古老的太古宙变质基底,是世界上矿床类型最丰富、资源聚集程度最高的成矿区之一。在太古宙花岗岩-绿岩为主体的结晶基底中,含有大量紫苏花岗岩、奥长花岗岩-英云闪长岩-花岗闪长岩(trondhjemite-tonalite-granodiorite,TTG)岩套和未完全解体的变质深成岩,目前对其认识仍存在较大分歧。岩浆岩的正确划分和精细研究是深入认识南美克拉通演化的重要手段,在调查卡拉加斯地区基底中变质侵入岩的基础上,结合前人资料将其进一步划分为中太古代的紫苏花岗岩、层状基性—超基性岩和TTG岩套,新太古代的基性—超基性杂岩、TTG岩套、同构造花岗岩、后构造花岗岩等,以及古元古代的碱性花岗岩。结合岩石学、地球化学和年代学方法综合分析了卡拉加斯地区的花岗质深成岩,锆石U-Pb测年获得的花岗岩^(207)Pb/^(206)Pb表面年龄集中在2899~2831 Ma、2742~2622 Ma和1919 Ma 3个时期,认为南美克拉通在经历了古太古代陆核形成、中太古代古大陆增生后,在太古宙末期和古元古代发生了二阶段的克拉通化过程,在中元古代—新元古代克拉通开始被破坏。通过对比南美克拉通与华北克拉通的早期演化过程,推测南美克拉通的构造演化早期受地幔柱控制,晚期转变为以板块构造为主导的大陆增生机制。研究有助于深入认识和对比矿集区成矿过程及其成矿效应。
基金supported by the National Natural Science Foundation of China (Grant No. 41305066)the Special Funds for Public Welfare of China (Grant No. GYHY201306045)the National Basic Research Program of China (Grant Nos. 2010CB951101 and 2010CB428403)
文摘Information on the spatial and temporal patterns of surface carbon flux is crucial to understanding of source/sink mechanisms and projection of future atmospheric CO2 concentrations and climate. This study presents the construction and implementation of a terrestrial carbon cycle data assimilation system based on a dynamic vegetation and terrestrial carbon model Vegetation-Global-Atmosphere-Soil(VEGAS) with an advanced assimilation algorithm, the local ensemble transform Kalman filter(LETKF, hereafter LETKF-VEGAS). An observing system simulation experiment(OSSE) framework was designed to evaluate the reliability of this system, and numerical experiments conducted by the OSSE using leaf area index(LAI) observations suggest that the LETKF-VEGAS can improve the estimations of leaf carbon pool and LAI significantly, with reduced root mean square errors and increased correlation coefficients with true values, as compared to a control run without assimilation. Furthermore, the LETKF-VEGAS has the potential to provide more accurate estimations of the net primary productivity(NPP) and carbon flux to atmosphere(CFta).
