Metamorphism of mineral matter in coal from the Bukit Asam deposit, south Sumatra, Indonesia   总被引：1，自引：3，他引：1  

Rita Susilawati  Colin R. Ward   《International Journal of Coal Geology》2006,68(3-4):171-195

The coal of the Miocene Bukit Asam deposit in south Sumatra is mostly sub-bituminous in rank, consistent with regional trends due to burial processes. However, effects associated with Plio–Pleistocene igneous intrusions have produced coal with vitrinite reflectance up to at least 4.17% (anthracite) in different parts of the deposit. The un-metamorphosed to slightly metamorphosed coals, with Rv_max values of 0.45–0.65%, contain a mineral assemblage made up almost entirely of well-ordered kaolinite and quartz. The more strongly heat-affected coals, with Rv_max values of more than 1.0%, are dominated by irregularly and regularly interstratified illite/smectite, poorly crystallized kaolinite and paragonite (Na mica), with chlorite in some of the anthracite materials. Kaolinite is abundant in the partings of the lower-rank coals, but is absent from the partings in the higher-rank areas, even at similar horizons in the same coal seam. Regularly interstratified illite/smectite, which is totally absent from the partings in the lower-rank coals, dominates the mineralogy in the partings associated with the higher-rank coal beds. A number of reactions involving the alteration of silicate minerals appear to have occurred in both the coal and the associated non-coal lithologies during the thermal metamorphism generated by the intrusions. The most prominent involve the disappearance of kaolinite, the appearance of irregularly interstratified illite/smectite, and the formation of regular I/S, paragonite and chlorite. Although regular I/S is identified in all of the non-coal partings associated with the higher-rank coals, illite/smectite with an ordered structure is only recognised in the coal samples collected from near the bases of the seams. The I/S in the coal samples adjacent to the floor of the highest rank seam also appears to have a greater proportion of illitic components. The availability of sodium and other non-mineral inorganic elements in the original coal to interact with the kaolinite, under different thermal and geochemical conditions, appears to be the significant factor in the formation of these new minerals, and distinguishes the mineralogical changes at Bukit Asam from those developed more generally with rank increases due to burial, and from the effects of intrusions into coals that were already at higher rank levels.  相似文献   

Gated communities, commodification and aestheticization: The case of the Lisbon metropolitan area     

Rita Raposo 《GeoJournal》2006,66(1-2):43-56

This paper focuses on the commodification processes and the aestheticization practices that shape gated communities and on the way these are connected to their segregational dimension, which is illustrated through the case of the Lisbon Metropolitan Area (LMA). First, I discuss the (increasing) aestheticization of commodities, emphasising some of the more problematic theoretical issues it involves. Following this discussion I present and analyse the ‘Lisbon case’. I provide a brief overview of gated communities in the LMA and then present and analyse the results obtained through a content analysis of LMA gated community advertisements and observation of their site semantics as conveyed through general built form, including physical location, planning, architecture, landscaping, and toponymy. I relate these findings to the LMA gated community market characteristics and to the broader prevailing socio-spatial context regarding their emergence.  相似文献   

Motional induction voltage measurements in estuarine environments: the Ria de Aveiro Lagoon (Portugal)     

Rita Nolasco  António Soares  João M. Dias  Fernando A. Monteiro Santos  N. A. Palshin  Patricia Represas  Nuno Vaz 《Geophysical Journal International》2006,166(1):126-134

  相似文献   

Structural evolution of the Pleistocene Cimini trachytic volcanic complex (Central Italy)     

Corrado Cimarelli  Donatella De Rita 《Bulletin of Volcanology》2006,68(6):538-548

Structural, geomorphological, geophysical and volcanological data have been processed for the implementation of a dedicated GIS through which the structural evolution of the Pleistocene trachytic Cimini volcano (central Italy) has been reconstructed. The evolution of the Cimini complex includes three main close-in time phases: (1) intrusion of a shallow laccolith, rising along NW and NE trending faults and stagnating at the contact between the Mesozoic-Cenozoic and the Pliocene-Pleistocene sedimentary units constituting the bedrock of the volcano; (2) emplacement of lava domes along radial and tangential fractures formed by the swelling induced by the laccolith growth; (3) ignimbrite eruptions and final effusion of olivine-latitic lavas. Domes are both of Pelean and low lava dome type and their morphology was controlled by the location on the inclined surface of the swelled area. Some domes show to have uplifted upper Pliocene thermally metamorphosed clay sediments, suggesting a cryptodome-like growth. Comparison of the top of the Mesozoic-Cenozoic units with the top of the upper Pliocene-Pleistocene sedimentary complex, suggests that the laccolith emplaced in a graben of the Mesozoic-Cenozoic sedimentary complex filled by the Pliocene–Pleistocene sediments uplifted by the shallow intrusion. Stress patterns acting on the Cimini area have been deduced analysing the drainage network and the morphotectonic lineaments. Rose diagrams show a large dispersion of the lineaments reflecting the local presence of radial and tangential fractures. The most frequent extensional NW and NE trending lineaments have regional significance and controlled the magma uprise leading to the laccolith emplacement.  相似文献   

A ~565 Ma old glaciation in the Ediacaran of peri-Gondwanan West Africa     

Linnemann  Ulf  Pidal  Agustín Pieren  Hofmann  Mandy  Drost  Kerstin  Quesada  Cecilio  Gerdes  Axel  Marko  Linda  Gärtner  Andreas  Zieger  Johannes  Ulrich  Jens  Krause  Rita  Vickers-Rich  Patricia  Horak  Jana 《International Journal of Earth Sciences》2018,107(3):885-911

International Journal of Earth Sciences - In the Cadomian orogen of the NE Bohemian Massif and of SW Iberia, a post-Gaskiers glacial event dated at c. 565 Ma has been detected. Such...  相似文献   

Assessment of future trends on groundwater quality in a nitrate vulnerable zone (Esposende–Vila do Conde sector,NW Portugal): towards a combined conceptual and mass transport modelling     

Zeferino  Joel  Carvalho  Maria Ros&#;rio  Lopes  Ana Rita  Jesus  Ros&#;rio  Afonso  Maria Jos&#;  Freitas  Liliana  Carvalho  Jos&#; Martins  Chamin&#;  Helder I. 《Hydrogeology Journal》2021,29(6):2267-2283

Hydrogeology Journal - Nitrate contamination of groundwater is an important public health issue worldwide. For environmental and public health reasons, water should not contain more than...  相似文献   

A principal component analysis approach to assess CHIRPS precipitation dataset for the study of climate variability of the La Plata Basin,Southern South America     

Cerón  Wilmar Loaiza  Molina-Carpio  Jorge  Ayes Rivera  Irma  Andreoli  Rita Valeria  Kayano  Mary Toshie  Canchala  Teresita 《Natural Hazards》2020,103(1):767-783

Natural Hazards - This article assesses the consistency of the satellite precipitation estimate CHIRPS v.2 to describe the spatiotemporal rainfall variability in the La Plata Basin (LPB), the...  相似文献   

Modelling intra-dependencies to assess road network resilience to natural hazards     

Der Sarkissian  Rita  Abdallah  Chadi  Zaninetti  Jean-Marc  Najem  Sara 《Natural Hazards》2020,103(1):121-137

Natural Hazards - Estimating the resilience of a road network (one of the essential critical infrastructures in times of crisis) to natural hazards is crucial in achieving the goals of disaster...  相似文献   

Erratum to “Evidence of estuarine nursery origin of five coastal fish species along the Portuguese coast through otolith elemental fingerprints” [Estuar. Coast. Shelf Sci. 79 (2008) 317–327]     

Rita P. Vasconcelos  Patrick Reis-Santos  Susanne Tanner  Anabela Maia  Christopher Latkoczy  Detlef Günther  Maria José Costa  Henrique Cabral 《Estuarine, Coastal and Shelf Science》2009

  相似文献   

Climatic simulations of the eastern Andes low-level jet and its dependency on convective parameterizations     

Maria Cristina Lemos da Silva  Rosmeri Porfírio da Rocha  Rita Yuri Ynoue 《Meteorology and Atmospheric Physics》2010,108(1-2):9-27

The South American low level jet (SALLJ) of the Eastern Andes is investigated with Regional Climate Model version 3 (RegCM3) simulations during the 2002–2003 austral summer using two convective parameterizations (Grell and Emanuel). The simulated SALLJ is compared with the special observations of SALLJEX (SALLJ Experiment). Both the Grell and Emanuel schemes adequately simulate the low level flow over South America. However, there are some intensity differences. Due to the larger (smaller) convective activity, the Emanuel (Grell) scheme simulates more intense (weaker) low level wind than analysis in the tropics and subtropics. The objectives criteria of Sugahara (SJ) and Bonner (BJ) were used for LLJ identification. When applied to the observations, both criteria suggest a larger frequency of the SALLJ in Santa Cruz, followed by Mariscal, Trinidad and Asunción. In Mariscal and Asunción, the diurnal cycle indicates that SJ occurs mainly at 12 UTCs (morning), while the BJ criterion presents the SALLJ as more homogenously distributed. The concentration into two of the four-times-a-day observations does not allow conclusions about the diurnal cycle in Santa Cruz and Trinidad. The simulated wind profiles result in a lower than observed frequency of SALLJ using both the SJ and BJ criteria, with fewer events obtained with the BJ. Due to the stronger simulated winds, the Emanuel scheme produces an equal or greater relative frequency of SALLJ than the Grell scheme. However, the Grell scheme using the SJ criterion simulates the SALLJ diurnal cycle closer to the observed one. Although some discrepancies between observed and simulated mean vertical profiles of the horizontal wind are noted, there is large agreement between the composites of the vertical structure of the SALLJ, especially when the SJ criterion is used with the Grell scheme. On an intraseasonal scale, a larger southward displacement of SALLJ in February and December when compared with January has been noted. The Grell and Emanuel schemes simulated this observed oscillation in the low-level flow. However, the spatial pattern and intensity of rainfall and circulation anomalies simulated by the Grell scheme are closer to the analyses than those obtained with the Emanuel scheme.  相似文献