陇西盆地晚第三纪风尘沉积的地层学研究

In Asia, the significant environment changes in Cenozoic include: uplift of Himalayas and Tibetan Plateau, formation Asian monsoon system, Aridification in Central Asia. One of major advances in recent studies of eolian deposit on the Loess Plateau is the verification of the eolian origin for the Late Tertiary Hipparion Red-Earth (also called red-Clay) underlying the Quaternary loess. Thus, the Late Tertiary eolian deposit, which has been proven a nearly continuous terrestrial record and sensitive to climate change, provides us an important archive to understand these above Cenozoic environment events. The deposit in eastern Loess Plateau has been extensively studied, while the property and age of deposit underlying the Quaternary loess in western plateau remains unclear. In this paper, detail investigations were made on the Sedimentology, geochemistry of Longxi section, a typical section in western Loess Plateau, to address its origin, and on micromammalian fossils and magnetostratigraphy to address its age. The main conclusions are presented as following: 1. The sedimentological and geochemical properties in Longxi section are highly similar to typical Quaternary eolian deposit in Loess Plateau. Nearly 100 paleosols are recognized in the field, and the grain size are very fine with the median grain size centered at 4～7μm. There is a good agreement of both major and trace element compositions between Longxi deposit and the Quaternary Loess. The REE distribution patterns of Longxi deposit and the Quaternary loess are remarkably similar in shape, with enrichment LREE and fairly flat HREE profiles and clear negative Eu anomaly. The mangnetic minerals in Longxi deposit are mainly magnetite, hematite and maghematite, which are similar to those of the Hipparion Red-Earth and Quaternary Loess. The major difference among them is that the samples from Longxi section contain more hematite. The characteristics of anisotropy of magnetic susceptibility (AMS) in Longxi deposit is highly consistent with that of Quaternary loess, while values of the major AMS parameters, e.g. anisotropy degree, magnetic foliation and lineation, are significantly lower than those of fluvial and lake deposits. These evidences indicate an eolian origin for the sediment. 2. An investigation of micromammalian fossils was firstly carried out for determining the approximate age of the sequence because of lack of materials for accurate isotope dating. Three fossil assemblages were obtained which indicate a chronological range from the Middle Miocene to Late Miocene. The magnetostratigraphical study suggests that it is a near continuous terrestrial record for the period from 13.23 to 6.23 MaB.P. The obtained chronology is highly consistent with fossils assemblages. This section is the oldest eolian deposit presently known in Loess Plateau. 3. The magnetic susceptibly value is high in paleosols than in surrounded weak-weathered layers, which suggests that it may be a climate index on orbital time scale. While it cannot be used as a proxy to address the long-term, change of climate on tectonic time scale, as content of the magnetic minerals is highly variable in different parts of the section. 4. The appearance of Middle Miocene eolian deposit in the Loess Plateau marks the strengthening of aridification of Central Asia. The high degree of similarity between the geochemical properties of Longxi eolian deposit, Hipparion Red-Earth and Quaternary loess a suggests that a rather similar source provenance. The dust accumulation rate (DAR) of Longxi section, which is widely used as a proxy to document the aridity in source areas in marine and terrestrial record studies, recorded the aridity condition in northwestern China over a period from Middle Miocene to Late Miocene. The DAR of the section shows that the continent aridity remains moderate and relative stable over that period.

Proposta de zoneamento geoambiental do município do Crato/CE

The geo-environmental zoning is an important means to plan the management of the territory, once it is the result of integration of different elements of the physical environment. The Municipality of Crato has a diversity of geo-environmental systems due to its complex landscape, which characterization and delimitation will contribute to the most appropriate occupation and the fewer prejudicial to municipal area. This study, which was supported by geo-systemic theory, searched to reach the following objectives: to elaborate a proposal of geo-environmental zoning; to characterize identified and demarcated geo-environmental systems, including their potentiality and limitations of land use and human occupation; and to generate a database on digital maps through GIS Geographic Information System. Four geo-environmental systems were identified (Chapada do Araripe: plateau and hillside, Massif and residual crest, Sertão of peripheric southern depression and fluvial Plains) and ten geo-environmental subsystems (Eastern plateau covered by cerradão/cerrado, Western plateau covered by cerrado/carrasco, Northern-west hillside, central residual Massif, Northern Residual Massifs, Sertaneja depression dominated by sedimentary materials, Sertaneja depression dominated by embasement crystalline material; wet fluvial plains and dry fluvial plains). The identified system and subsystem are similar to those proposed by FUNCEME in spite of some changes due to the more detailed mapping

Florística de uma Floresta Estacional Semidecidual, localizada em ecótono savânico-florestal, no município de Bauru, SP, Brasil

Informações florísticas escassas, referentes ao município de Bauru, e a elaboração de hipóteses sobre mecanismos de ocupação de fitocenoses florestais por espécies savânicas, representaram as principais questões motivadoras do presente estudo, desenvolvido em dois fragmentos de floresta estacional semidecidual (5 ha e 7 ha) mantidos pelo Jardim Botânico de Bauru, que abriga também savana florestada. O material botânico foi coletado a partir de caminhadas ao acaso e em parcelas implantadas durante estudo fitossociológico. Foram encontradas 264 espécies arbustivo-arbóreas, pertencentes a 58 famílias. Dessas espécies 126 foram coletadas apenas na fitocenose florestal, e 66 espécies foram coletadas em ambas as fitocenoses. As duas famílias com o maior número de espécies foram Rubiaceae (25 espécies) e Myrtaceae (21 espécies). Foi realizada análise de similaridade florística, a partir do índice de Jaccard (SJ), entre a floresta do JBMB e outros 11 remanescentes florestais, alguns dos quais, sob influência florística savânica. A riqueza florística dos fragmentos florestais do JBMB sofreu incremento, pela ocupação de espécies savânicas, oriundas da savana florestada contígua. Incêndios pretéritos, além da ocorrência de microambientes distintos, representaram prováveis fatores de facilitação para a invasão dessas espécies savânicas.

Extratores para nitrogênio disponível do solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cronogeomorfologia do relevo da cidade de Marília através do método de traços de fissão - MTF

Pós-graduação em Geografia - FCT

Sistemas de produção de porta-enxertos de seringueira

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Relações entre variáveis ambientais e anfíbios anuros em áreas de cerrado e floresta estacional semidecidual

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estado nutricional e avaliação de caracteres secundários da produção em dois clones jovens de seringueira em São José do Rio Preto, SP

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise morfotectônica do Planalto Ocidental Paulista, ao sul do Rio Tietê: indicadores de deformações neotectônicas na fisiografia da paisagem

Pós-graduação em Geologia Regional - IGCE

Contribution of inherent organic carbon to the bulk delta C-13 signal in loess deposits from the arid western Chinese Loess Plateau

IEECAS SKLLQG