Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Rancho Sana Ana Botanic Garden (RSA), Claremont, CA & the Florida Museum of Natural History (FLAS), Gainesville, FL, USA & Jardín Botánico National, La Habana, Cuba
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Cuba -- Guantanamo -- La Maquina

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at the Florida Museum of Natural History (FLAS), Gainesville, FL, USA
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Mexico -- Tabasco -- Cardenas

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Metasedimentary rocks in the transition zone between the Pernambuco-Alagoas Domain and the Sergipano Belt (southern Borborema Province, NE Brazil) were studied in order to place constraints on the geological evolution of this portion of West Gondwana. High-grade metamorphic conditions are recorded by the garnet-sillimanite assemblage and common anatexis in pelitic paragneisses. Two samples dated by LA-ICP-MS in the north yielded a predominance of early Neoproterozoic detrital zircons, with age peaks between 990 Ma and 827 Ma, with the youngest grain suggesting deposition after 670 Ma. Low Th/U zircons (Th/U < 0.1) in these samples display a significant spread in ages, from 691 to 568 Ma. One sample in the south is dominated by a homogenous population of Paleoproterozoic grains, with a 2200 Ma peak. The southernmost sample also contains Paleoproterozoic zircons but the most abundant population is Neoproterozoic, and characterized by age peaks at c. 670, 647 and 623 Ma. These results show that deposition of sediments in the southern PEAL Domain and in the northern Sergipano Belt occurred in the Late Neoproterozoic. The differing age spectra between samples are correlated with potential source rocks in the study area or in its proximity, reflecting variable input from local sources. The data are interpreted to indicate that during the course of an extensional event at c. 673-647 Ma, Tonian granitic intrusions and synextensional metamorphic rocks were unroofed and eroded to provide zircons for sediments deposited in the north, whereas Paleoproterozoic and synextensional magmatic rocks were the main sources for sediments in the south. Peak metamorphic conditions and contractional deformation are constrained to c. 630-600 Ma.
ISSN: 0895-9811

hal-01468011
https://hal.archives-ouvertes.fr/hal-01468011
DOI : 10.1016/j.jsames.2016.09.010

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA
Dominica -- Saint Sauveur

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at the Florida Museum of Natural History (FLAS), Gainesville, FL, USA
Jamaica -- St. Thomas -- Johnson Mountain

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National, La Habana, Cuba
Cuba -- Guantanamo -- near Moa

Résumé : Written on verso: "Nodulizing Plant. Convert ore into nodules."
1920-1930
CHC5017
Cuba

Droits : http://merrick.library.miami.edu/digitalprojects/copyright.html
chc50170000830001001
1356

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Rancho Sana Ana Botanic Garden (RSA), Claremont, CA & the Florida Museum of Natural History (FLAS), Gainesville, FL, USA & Jardín Botánico National, La Habana, Cuba
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Cuba -- Guantanamo -- La Maquina

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National, La Habana, Cuba
Cuba -- Guantanamo -- Moa

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA
Dominica -- Saint Sauveur

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at the Florida Museum of Natural History (FLAS), Gainesville, FL, USA
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Barbados -- St. Peter Parish

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National Rafael Moscoso (JBSD), Santo Domingo, Dom. Rep.
specimen cited in: Zona, S. 2002. A revision of Pseudophoenix. PALMS 46: 19–38.
Dominican Republic -- Barahona

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at the Florida Museum of Natural History (FLAS), Gainesville, FL, USA
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Barbados -- St. Peter Parish

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
Voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National, La Habana, Cuba
see publication: Zona, S. 1995. Anthurium gymnopus in Cuba. Aroideana 18: 21–23.
Cuba -- Pinar del Río (Province)

Éditeur(s) : HAL CCSD Springer/Terra Scientific Publishing Company
Résumé : International audience
We report oil the discovery of magnetite nanoparticles ranging in size from 2 to 14 full in the mineralized zones of the Pena Colorada iron-ore deposit, southern Mexico. Micrometric scale magnetite was magnetically reduced and divided into distinct size ranges: 85-56 mu m, 56-30 mu m, 30-22 mu m, 22-15 mu m, 15-10 mu m, 10-7 mu m and 7-2 mu m. Nanometric-scale magnetite in the size range 2-14 nm was identified. The magnetite was characterized by X-ray diffraction, transmitted and reflected light microscope, high-resolution transmission electron microscopy (TEM), high angle annular dark field, Mossbauer spectroscopy and its magnetic properties. Crystallographic identification of nanostructures Was performed using high-resolution TEM. Characteristic changes were observed when the particles make the size transition from micro- to nanometric sizes, as follows: (1) frequency-dependent magnetic Susceptibility percentage (chi FD%) measurements Show high Values (13%) for the 2-14 nm fractions attributed to dominant fractions of superparamagnetic particles; (2) variations of chi FD% < 4.5% in fractions of 56-0.2 mu m occur in association with the presence of microparticles formed by magnetite aggregates of nanoparticles (< 15 nm) embedded in berthierine; (3) Mossbauer spectroscopy results identified a superparamagnetic fraction; (4) nanometric and 0.2-3 mu m grain size magnetite particles require a magnetic field up to 152 mT to reach saturation during the isothermal remanent magnetization experiment; (5) coercivity and remanent magnetization of the magnetite increase when the particle size decreases, probably due to parallel Coupling effects; (6) two-magnetic Susceptibility versus temperature experiments of the same 2-14 nm sample show that the reversibility during the second heating is due to the formation of new magnetite nanoparticles and growth of those already present. during the first heating process.
ISSN: 1343-8832

hal-00413053
https://hal.archives-ouvertes.fr/hal-00413053

Éditeur(s) : HAL CCSD
Résumé : The Franceville Basin (2.1 Ga) in southeastern Gabon, hosts a black shale series well preserved (FB Formation) which represents an exceptional example of unmetamorphised Paleoproterozoic sediment strata. This basin includes the protore of one of the largest Mn-oxide laterite ore worldwide, mined by Eramet-Comilog. The aim of this this work is to determine formation conditions of this protore and to characterize the global sedimentary evolution of the FB Formation which include the protore. This 75 m thick protore is constituted of Mn carbonate-rich black shales which represent a potential ore deposit for the future. It was drilled, on the Bangombé plateau, during a recent campaign of 24 boreholes with an average depth of 125 m.Through multidisciplinary study on these cores and key outcrops of the basin, this work focuses on : i) the depositional environment of the Mn-protore and FB Formation ; ii) the processes of formation of the Mn-carbonates at 2.1 Ga and iii) the architecture and distribution of Mn-rich levels of the protore on the Bangombé Plateau.A detailed sedimentological and petrological study allowed us to redefine the division of the FB into nine units, named U1 to U9 from the base to the top. These units show a fine upward cycle up to U5 and a reverse coarse loop until U9. This division leads to a new interpretation to propose an evolution from a shoreface depositional environment controlled by deltaic currents (U1) to an offshore depositional environment with anoxic conditions (U2). In this basin, a system of submarine fan is developed, feeding a network of sand injections (injectites) covering the Bangombé plateau (70 km²) and with a thickness of 150 m affecting U4 to U7, including the Mn-protore. The protore depositional environment formed below the wave base limit (U4, U5 and U6) in a starved basin, controlled by biochemical sedimentation allowed the formation of Mn-carbonates. The end of starved basin, would allow the re-opening of the detrital input into the offshore basin (U7). This basin is then filled by storm bar deposits intersected by deltaic sub-aquatic channels (U8). The U9 unit corresponds to a quiet lagoon environment, allowing the multicellular organism development for the first time on the planet.A geochemical study allowed the characterization of the depositional environment of Mn-carbonates as an anoxic to sub-oxic and alkaline environment. For the first time, we showed that the manganese carbonates, present as bacteriomorph forms, are precipitated from the seawater by the mediated photosynthetic cyanobacterial activity, which allows CO2 / HCO3 depression of the environment and a local increase of pH. The cyanobacterial activity is controlled by the absence of bottom currents, which increase the detrital input. This would stop the activity of the cyanobacteria and thus would lead to the decrease of the Mn-concentration along the protore.Finally, well-log and a sequential correlation analyses allowed us to detail spatial and timing repartition of FB Formation deposit, controlled by a tectono-sedimentary model. We propose two- tectono-sedimentary phases. A first syn-tectonic phase (U1 to U3) controls the depocentres and sedimentation gaps. Turbidite coarse deposits are located in the most subsident part, clay deposits rather on the slope and carbonates on shoals. A second post-tectonic phase (U4 to U7) allows isopach deposits. The Mn-protore formed during the post-tectonic phase. However, it shows a variable thickness due to subsidence to the north of the Bangombé plateau. So, on the Bangombé plateau, Mn-contents increase towards the south, whereas the protore thickness increases towards the NNE. Moreover sand injectites decrease Mn-content in the eastern part of the Bangombé plateau and impact on the economic evaluation of the Mn-carbonates. Currently, the protore is structured by post-sedimentary faults, which lead to a non-continuity of the high Mn levels on the Bangombé plateau.
Le Bassin de Franceville situé au SE du Gabon présente une série de black shales (Formation FB) d'âge Paléoprotérozoïque (2,1 Ga) surmontant les grès de la Formation FA. Ce bassin peu déformé et non métamorphique représente une archive exceptionnelle des processus de dépôt de cette période de l’histoire de la Terre où la vie commence à se développer. En particulier, la Formation FB contient le protore d'un gisement mondial d'oxydes de manganèse exploité par la société Eramet-Comilog. L’objectif de ce travail est de préciser les conditions de formation de ce protore et de le replacer dans l’histoire du remplissage du bassin. Ce protore d'une épaisseur moyenne de 75 m est constitué de carbonates de manganèse ; il a fait l'objet d'une récente campagne de 24 forages carottés d'une profondeur moyenne de 125 m sur le plateau de Bangombé.A travers une approche pluridisciplinaire comprenant l'étude de ces forages et des affleurements clefs du bassin, ce travail porte sur la caractérisation i) de l'environnement de dépôt du protore et des séries qui l'encadrent (du toit du FA au toit du FB) ; ii) du mode de formation des carbonates de Mn à 2,1 Ga et iii) de l'architecture et de la répartition des hautes teneurs en Mn du protore qui représente un gisement potentiel du futur.L’étude pétro-sédimentaire détaillée a permis de distinguer neuf unités (U1 à U9) au sein de la Formation FB organisées suivant un cycle rétrogradant jusqu’à U5 puis progradant jusqu’à U9. Ce découpage montre une évolution du milieu de dépôt depuis un domaine de shoreface contrôlé par des courants deltaïques (U1) évoluant vers des dépôts d’offshore restreint (U2). Ce bassin enregistre ensuite un système de chenaux-levées turbiditiques (U3) qui alimentent un réseau d'injectites reconnu sur l’ensemble du Pl. de Bangombé et qui traverse 150 m de série (U4 à U7) en affectant le protore et ainsi les teneurs en Mn. L'environnement de dépôt du protore (U5 et U6) marque l’isolement du bassin qui devient affamé et contrôlé par une sédimentation biochimique à l’origine du dépôt des carbonates de Mn. L'Unité 7 correspond à la réouverture des apports détritiques en domaine d'offshore supérieur puis en domaine de shoreface dominé par des dépôts de tempêtes et de chenaux sous-aquatiques deltaïques (U8), et enfin lagunaire (U9) dans lequel apparaissent les premiers métazoaires de l’histoire de la planète, suivant une séquence régressive.Une étude géochimique a permis de préciser les conditions de dépôt du protore qui se forme en milieu alcalin anoxique à sub-oxique. Dans ce milieu, nous montrons pour la première fois une précipitation directe des carbonates de Mn sous forme bactériomorphe induite par l'activité photosynthétique des cyanobactéries qui consomment le CO2/HCO3 et conduisent à une augmentation du pH favorable à la formation des carbonates de Mn. L'activité cyanobactérienne est conditionnée par l’absence de courants de fond qui augmentent la turbidité du milieu et stoppent cette dernière.Les corrélations diagraphiques et séquentielles permettent de préciser la répartition spatiale et temporelle du FB permettant ainsi de replacer le protore dans l’histoire tectono-sédimentaire du bassin. Une première phase syn-tectonique (U1 à U3) contrôle l’épaisseur et la mise en place de dépôts turbiditiques dans les parties subsidentes, de dépôts argileux sur les pentes et de dépôt de carbonates sur les hauts-fonds. La seconde phase post tectonique (U4 à U7) permet la mise en place de dépôts relativement isopaques, bien que le protore enregistre une subsidence plus importante au nord du Pl. de Bangombé. On observe ainsi, sur le Plateau de Bangombé, des teneurs en Mn qui augmentent vers le sud alors que l’épaisseur du protore augmente vers le NNE. Postérieurement au dépôt du FB, le protore est structuré par des failles qui le compartimentent en touches de piano limitant ainsi sa continuité sur le Plateau de Bangombé.
https://hal.archives-ouvertes.fr/tel-01621460

tel-01621460
https://hal.archives-ouvertes.fr/tel-01621460
https://hal.archives-ouvertes.fr/tel-01621460/document
https://hal.archives-ouvertes.fr/tel-01621460/file/these_Dubois2017-MnGabon.pdf

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National, La Habana, Cuba
Cuba -- Guantanamo -- near Cajobabo, Imias

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Fairchild Tropical Botanic Garden (FTG), Miami, FL, USA & Jardín Botánico National, La Habana, Cuba
Cuba -- Pinar del Rio

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Rancho Sana Ana Botanic Garden (RSA), Claremont, CA & the Florida Museum of Natural History (FLAS), Gainesville, FL, USA & Jardín Botánico Rafael Moscoso (JBSD), Santo Domingo, Dom. Rep.
specimen cited in: Zona, S. 1996. Roystonea (Arecaceae: Arecoideae). Flora Neotropica 71: 1–36.
Dominican Republic -- Puerto Plata

Résumé : 2009, Scott Zona -- CC: at-ncsa (Creative Commons license requiring attribution, prohibiting commercial uses, and requiring rights-share for use of this image)
voucher specimen deposited at Rancho Sana Ana Botanic Garden (RSA), Claremont, CA & the Florida Museum of Natural History (FLAS), Gainesville, FL, USA & Jardín Botánico Rafael Moscoso (JBSD), Santo Domingo, Dom. Rep.
specimen cited in: Zona, S. 1990. A monograph of Sabal (Arecaceae: Coryphoideae). Aliso 12: 583–666.
Dominican Republic -- Barahona