Carlin-type Gold Prospects in Surigao del Norte, Mindanao Island, Philippines: Their Geology and Mineralization Potential     

Victor B. Maglambayan    Sj Montes    Katherine Hipol    Maireen Mamitag    Rikki Pamela Pineda    Raymond Rodolfo    Noel Oliveros  Antonio Sy 《Resource Geology》2005,55(3):145-154

Abstract. Three calcareous sedimentary rock-hosted Carlin type-like gold prospects were mapped in a mineral production sharing agreement area of Philex Gold Philippines Inc. in Taganaan municipality, Surigao del Norte province in Mindanao island in the Philippines. They occur along a 20–25 km long trend of known epigenetic gold and porphyry copper deposits that lie close to several splays of the Philippine Fault Zone. The gold district forms part of the Late Cretaceous Eastern Mindanao Range that hosts early Paleogene and late Pliocene to Quaternary intrusive rocks.
Gold is invisible in the jasperoid outcrops in Lascogon, Napo, and Danao prospects. The jasperoids occur in lenses of marls belonging to the Taganaan Marl Member that is associated to a turbiditic member of the Middle Miocene Mabuhay Formation. The marl lenses include gently dipping interbedded silty limestones and calcareous shales. The "invisible gold" mineralization in silicified calcareous rocks resembles Carlin-type deposits. Based on the mapped igneous and sedimentary rocks, a possible heat source for the gold mineralization is either or both of the two main phases of intrusion, Mabuhay An-desite or Alipao Andesite Porphyry. Forty-eight rock samples, fifteen stream sediment samples, and one soil sample were critical in delineating the general features of the potential Carlin-type prospects. The gold grades of jasperoids in the three prospects range from trace amounts to 20 g/t Au. Regional studies of gold and porphyry copper mineralization in the Surigao del Norte mineral district are important in delineating ore targets for drilling in the three prospects.  相似文献   

Types of Pyrophyllite Deposits in Foldbelts     

Irina Sinyakovskaya    Victor Zaykov  Ryuji Kitagawa 《Resource Geology》2005,55(4):405-418

Abstract. Pyrophyllite deposits can be divided into five types on the basis of geology and genesis. The first two types are associated with hydrothermally altered rocks in felsic and intermediate volcanogenic suites. They are characterized by their metasomatites and their subsequent mineralogic transformations under varying volcanic conditions. The third type includes deposits and occurrences of metamorphic-metasomatic genesis, which is caused by transformations of terrigenous-sedimentary interbeds in felsic volcanics under greenschist facies conditions. The fourth type is associated with low and mid-temperature stages of hydrothermal vein formation at the limits of volcanogenic and metamorphic strata. The fifth type comprises pyrophyllite occurrences in weathering crusts on metamorphic strata and metasomatite.
The formation conditions and distribution of raw pyrophyllite deposits were influenced by the geodynamic situations and geochemical conditions, such as character of tectonic dislocations, volcanism and chemical composition of hydrothermal solutions.  相似文献   

Thérèse Mound: a case study of coral bank development in the Belgica Mound Province,Porcupine Seabight     

Ben De Mol  Max Kozachenko  Andy Wheeler  Hugo Alvares  Jean-Pierre Henriet  Karine Olu-Le Roy 《International Journal of Earth Sciences》2007,96(1):103-120

High-resolution seismic profiles, swath bathymetry, side-scan sonar data and video imageries are analysed in this detailed study of five carbonate mounds from the Belgica mound province with special emphasis on the well-surveyed Thérèse Mound. The selected mounds are located in the deepest part of the Belgica mound province at water depths of 950 m. Seismic data illustrate that the underlying geology is characterised by drift sedimentation in a general northerly flowing current regime. Sigmoidal sediment bodies create local slope breaks on the most recent local erosional surface, which act as the mound base. No preferential mound substratum is observed, neither is there any indication for deep geological controls on coral bank development. Seismic evidence suggests that the start-up of the coral bank development was shortly after a major erosional event of Late Pliocene–Quaternary age. The coral bank geometry has been clearly affected by the local topography of this erosional base and the prevailing current regime. The summits of the coral banks are relatively flat and the flanks are steepest on their upper slopes. Deposition of the encased drift sequence has been influenced by the coral bank topography. Sediment waves are formed besides the coral banks and are the most pronounced bedforms. These seabed structures are probably induced by bottom current up to 1 m/s. Large sediment waves are colonised by living corals and might represent the initial phase of coral bank development. The biological facies distribution of the coral banks illustrate a living coral cap on the summit and upper slope and a decline of living coral populations toward the lower flanks. The data suggest that the development of the coral banks in this area is clearly an interaction between biological growth processes and drift deposition both influenced by the local topography and current regime.  相似文献   

Multiple causes of Earth's earliest global glaciation   总被引：1，自引：0，他引：1  

Victor A. Melezhik 《地学学报》2006,18(2):130-137

In the context of Earth System evolution, the causal factors driving the Palaeoproterozoic Huronian global glaciations occupy a central position. The rise of O₂ at 2320 Ma, which eliminated most of the methane, was not apparently a single cause triggering the glaciation. At c. 2450 Ma mantle‐plume‐driven continental uplifts led to the emplacement of voluminous continental flood‐basalts in low latitudes that were subsequently dissected by rifting. Major topographical features and continental drainage patterns were most likely similar to those in younger continental flood‐basalt provinces and would have enabled deep weathering and erosion of extensive basalt‐covered continental areas. Intense consumption of atmospheric CO₂ by silicate weathering of fresh basaltic surfaces would have been further amplified by a constant organic carbon burial rate. These factors, similar to those of younger glacial periods, in combination with the diminished CH₄ greenhouse led to an onset of global cooling at the million‐year timescale.  相似文献   

Kinematics of the Inntal shear zone–sub-Tauern ramp fault system and the interpretation of the TRANSALP seismic section, Eastern Alps, Austria     

Hugo Ortner  Franz Reiter  Rainer Brandner 《Tectonophysics》2006,414(1-4):241

A new interpretation of the Inntal–Tauern sector of the TRANSALP seismic section is presented. One of the most prominent contrasts in reflectivity in the TRANSALP seismic section is the contact between the Bajuvaric unit in the footwall and the overlying Tirolic unit and its basement across a moderately south-dipping interface. We trace this contact from the surface at the southern margin of the Inn valley to a depth of 5 km. There, the contact is deformed or cut by the Tauern Window northern margin. We define the contact between Bajuvaric and Tirolic units as Brixlegg thrust, which is older than Miocene Tauern window exhumation and has a Paleogene age. The sub-Tauern ramp connects with the Inntal fault system at the surface and roots below the Tauern window. Oblique thrust movements across this fault system in the Miocene caused exhumation of the hanging wall, where the fault has a ramp geometry, which is in the area of the TRANSALP cross section and west of it. East of the TRANSALP cross section, the fault system merges with Alpine basal thrust, which is a flat. No Miocene exhumation occurred above the flat.  相似文献   

Distribution of Precambrian iron and gold deposits on the southwestern East European Platform reflected in underlying transcrustal structure and current river systems     

Hugo de Boorder  Maarten J. Zeylmans van Emmichoven  Vitaliy A. Privalov 《Ore Geology Reviews》2006,29(3-4):242-259

The East European Platform is underlain by Archaean and Proterozoic complexes of the East European Craton. In the southwest these are locally exposed in the Ukrainian Shield and the Voronezh Massif on either side of the ca. 2000 km long ESE-striking late Palaeozoic Pripyat–Dniepr–Donets rift. Evaluation with Landsat imagery of 1 : 1,000,000 scale published maps of the Precambrian complexes [Zaritsky, A.I., Galetsky, L.S. (Eds.), 1992. Geology and Metallogeny of the Southwest of the East-European Platform Map Series, 1 : 1,000,000, Ukrainian State Committee on Geology and Utilization of Mineral Resources, Kiev.] is largely obstructed by a cover of post-Palaeozoic sediments and soils of variable thickness. This obstruction is aggravated by an almost continuous patchwork of farmlands. However, analysis of the current drainage patterns in the Dniepr River basin and surrounding regions reveals a spatial coincidence of numerous stream courses and watersheds with previously inferred steep, transcrustal discontinuities of most probably Precambrian age.Transcrustal dislocations constituted important pathways for heat and fluids as is indicated by the distribution of a large proportion of assumed Early Proterozoic hydrothermal iron and gold deposits along them. This distribution is underpinned by the spatial coincidence of mineralization and elongate areas of highly irregular magnetization attributed to uneven distribution of hydrothermal magnetite in banded iron formation. In view of the extent of these dislocations, both vertically and laterally, the generation of hydrothermal fluid flow, emplacement of mantle-sourced magma and associated mineral potential away from banded iron formation complexes is likely. A second group of gold deposits, of Archaean age, is known to occur in association with still recognizable volcanic edifices in greenstone complexes. It is not known if and to what extent such Archaean gold deposits are related to these major transcrustal discontinuities. The kinematics and dynamics of these dislocations and pathways appear largely unknown and deserve high-priority investigation. The geological longevity of the transcrustal dislocation framework till the present day inferred from the current drainage systems is corroborated, however, by repeated regional topographical levelling surveys.  相似文献   

Temporary Migration and the Labour Market in Australia     

Graeme Hugo 《The Australian geographer》2006,37(2):211-231

Australia's labour market is most influenced by international migration among OECD nations, but Australian research on this issue focuses almost exclusively on permanent settlement migration. The present paper, however, demonstrates that non-permanent migration has an important impact on the Australian labour market, although such migrants are not included in standard data collections and research on migrants and the labour market. A number of data sources are utilised to estimate the labour-market impact of Working Holiday Makers, Temporary Business Entrants, Overseas Students, and New Zealand temporary migrants. It is shown that their impact is equivalent to more than 400?000 full-time jobs. However, the effect is magnified because it is concentrated in particular sectors of the economy and in particular communities within Australia. A number of issues relating to temporary migration are discussed, including the nature of its relationship with permanent migration, the effects on job training, and the implications for regional development.  相似文献   

A New Analytic Integration of the Rate Equation for Batch Dissolution of Salts in the Presence of Common Ion     

Victor W. Truesdale  Cristiana Sebu 《Aquatic Geochemistry》2013,19(1):39-56

Following a recent suggestion of a new rate equation specifically for the batch dissolution of salts in solutions containing a common ion, this paper describes an analytic solution to its integration. The equation has been tested by dissolving 250???m gypsum- rock particles in water (26.7?g?l^?1) containing various mixtures of sodium and calcium chlorides, all at an ionic strength of 0.060?M. The model fitted the experimental curves very well and showed that the dissolution slowed slightly overall when the initial calcium concentration was increased from 0 to 0.020?M. The dissolution curves were also modelled as a simple exponential, whence the fit was comparable to that with the new equation, with the exponential rate constant varying between 0.025 and 0.019 (±0.0004) for 0 and 0.020?M initial calcium concentration, respectively. Conventional Electrolyte theory from thermodynamics is used to show that the new equation is an inevitable consequence of modelling the net rate of dissolution in terms of a back reaction that is first order with respect to the dissolved substance, as per the recently described Shrinking Object model. Moreover, it is shown how the simple exponential model (which is a well-used plot in dissolution kinetics) provides the linear end-member to an infinite number of curvilinear plots of rate of dissolution versus reaction progress developed by the new model??it is the special case where common ion is absent. The results are now judged good enough to identify a generic batch dissolution rate equation for all salts dissolving without significant complication from either contaminants or their own gaseous species, as in calcium carbonate dissolution.  相似文献   

TAPAS, a VO archive at the IRAM 30-m telescope     

Stephane Leon  Victor Espigares  José Enrique Ruíz  Lourdes Verdes-Montenegro  Rainer Mauersberger  Walter Brunswig  Carsten Kramer  Juan de Dios Santander-Vela  Helmut Wiesemeyer 《Experimental Astronomy》2012,34(1):65-88

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FedIDS: a federated cloud storage architecture and satellite image delivery service for building dependable geospatial platforms     

J. L. Gonzalez-Compean  Victor J. Sosa-Sosa  Arturo Diaz-Perez  Jesus Carretero  Ricardo Marcelin-Jimenez 《International Journal of Digital Earth》2018,11(7):730-751

Earth observation satellites produce large amounts of images/data that not only must be processed and preserved in reliable geospatial platforms but also efficiently disseminated among partners/researchers for creating derivative products through collaborative workflows. Organizations can face up this challenge in a cost-effective manner by using cloud services. However, outages and violations of integrity/confidentiality associated to this technology could arise. This article presents FedIDS, a suite of cloud-based components for building dependable geospatial platforms. The Fed component enables organizations to build shared geospatial data infrastructure through federation of independent cloud resources to withstand outages, whereas IDS avoids violations of integrity/confidentiality of images/data in sharing information and collaboration workflows. A FedIDS prototype, deployed in Spain and Mexico, was evaluated through a study case based on a satellite imagery captured by a Mexican antenna and another based on a satellite imagery of a European observation mission. The acquisition, storage and sharing of images among users of the federation, the exchange of images between Mexican and Spanish sites and outage scenarios were evaluated. The evaluation revealed the feasibility, reliability and efficiency of FedIDS, in comparison with available solutions, in terms of performance, storage consume and integrity/confidentiality when sharing images/data in collaborative scenarios.  相似文献