A new approach to the Late Miocene-Early Pliocene forms of the genus Apocricetus. Apocricetus alberti (Rodentia,Mammalia) from Venta del Moro (Cabriel Basin,Spain)     

Samuel Mansino  Francisco Javier Ruiz-Sánchez  Matthijs Freudenthal  Plinio Montoya 《Proceedings of the Geologists' Association. Geologists' Association》2014

The species of the genus Apocricetus are considered to form the phyletic lineage A. aff. plinii (MN11)–A. plinii–A. alberti–A. barrierei–A. angustidens (MN16). Along this lineage, gradual morphological and biometrical changes occur, but not all the species are represented by rich populations. The assemblage of Apocricetus alberti from Venta del Moro is by far the most abundant collection of this species. This population shows a great morphological variability in some characters like the morphology of the anteroconid and the anterolophulids in m1 and the shape of the anterolophule in M1, with morphotypes that resemble both older and younger populations of Apocricetus. Along the phyletic lineage of Apocricetus, a change in the shape of m3 occurs, from predominantly subtriangular forms in the oldest populations to predominantly subrectangular in the youngest. To quantify this feature we use the posterior width of the molar and the anterior width/posterior width ratio, proposing five morphological categories, from extremely triangular to subrectangular.  相似文献   

Genetic seascape of the threatened Caribbean elkhorn coral,Acropora palmata,on the Puerto Rico Shelf          下载免费PDF全文

Pascal Mège  Nikolaos V. Schizas  Joselyd Garcia Reyes  Tomas Hrbek 《Marine Ecology》2015,36(2):195-209

It has been proposed that the elkhorn coral Acropora palmata is genetically separated into two distinct provinces in the Caribbean, an eastern and a western population admixing in Western Puerto Rico and around the Mona Passage. In this study, the genetic structure of A. palmata sampled at 11 Puerto Rican localities and localities from Curaçao, the Bahamas and Guadeloupe were examined. Analyses using five microsatellite markers showed that 75% of sampled colonies had unique genotypes, the rest being clone mates. Genetic diversity among genets was high (H_E = 0.761) and consistent across localities (0.685–0.844). F_ST ranged from ?0.011 to 0.047, supporting low but significant genetic differentiation between localities within the previously reported eastern and western genetic provinces. Plots of genetic per geographic distances and significant Mantel tests supported isolation‐by‐distance (IBD) within Puerto Rico. Analysis with the software STRUCTURE favored a scenario with weak differentiation between two populations, assigning Eastern Puerto Rican locations (Fajardo and Culebra), Guadeloupe and Curaçao to the Caribbean eastern population and Western Puerto Rican locations (west of Vega Baja and Ponce), Mona and the Bahamas to the Caribbean western population. Vieques and San Juan area harbored admixed profiles. Standardized F_ST per 1000 km unit further supported higher differentiation between localities belonging to different STRUCTURE populations, with IBD being stronger within Puerto Rico than on larger regional scales. This stronger genetic transition seems to separate localities between putative eastern and western provinces in the Eastern Puerto Rican region, but not around the Mona Passage.  相似文献   

PETROCHEMICALS AND ECONOMIC DEVELOPMENT: THE IMPLICATIONS OF THE PUERTO RICAN EXPERIENCE*     

Keith Chapman 《The Professional geographer》1982,34(4):405-416

The oil refining and petrochemical industries have occupied an important role in Puerto Rico's development strategy since the early 1960s. However, the hopes epitomized in various planning models of highly integrated and diversified oil-based industrial complexes have not been fulfilled. This paper attempts to account for the discrepancy between official expectations and subsequent events in Puerto Rico and indicates some of the lessons for other developing countries.  相似文献   

Geochronological, isotopic, and geochemical data from Permo-Triassic granitic gneisses and granitoids of the Colombian Central Andes   总被引：1，自引：1，他引：1  

C.J. Vinasco  U.G. Cordani  H. Gonzlez  M. Weber  C. Pelaez 《Journal of South American Earth Sciences》2006,21(4):355

New U–Pb SHRIMP ages in zircon, Ar–Ar ages in micas and amphiboles, Nd–Sr isotopes, and major and REE geochemical analyses in granitic gneisses and granitic stocks of the Central Cordillera of Colombia indicate the presence of a collisional orogeny in Permo-Triassic times in the Northern Andes related to the construction of the Pangea supercontinent. The collision is recorded by metamorphic U–Pb SHRIMP ages in inherited zircons around 280 Ma and magmatic U–Pb SHRIMP ages in neoformed zircons around 250 Ma within syntectonic crustal granitic gneisses. Magmatic U–Pb SHRIMP and Ar–Ar Triassic ages around 228 Ma in granitic stocks indicate the presence of late tectonic magmatism related to orogenic collapse and the beginning of the breakup of the supercontinent. During this period, the Central Cordillera of Colombia would have been located between the southern United States and northern Venezuela, in the leading edge of the Gondwana supercontinent.  相似文献   

Identifying population vulnerable to hydrological hazards in San Juan, Puerto Rico     

Derek Azar  David Rain 《GeoJournal》2007,69(1-2):23-43

The hazards of place framework developed by Cutter (1996) has been applied to several areas across the United States. This article tests the applicability of that model for analysis of hydrological disasters in the municipio of San Juan, Puerto Rico. San Juan is chosen because it combines many socioeconomic attributes of a developing area while offering data availability befitting its status as a US commonwealth. The interoperability of principal components and arithmetically based methods for producing a social vulnerability layer are examined. For both methods, a basket of commonly cited demographic variables representing social and economic vulnerability is extracted from Census 2000 sample (SF-3) data at the census block-group level of analysis. These results provide insight on the strengths and weaknesses of the methods both methodologically and regarding policy implementation. A look at the neighborhood of La Perla suggests complex local positive and negative effects of local processes on vulnerability not captured by demographic analysis. These effects relate to possible census undercounts in peripheral areas and uncaptured coping ability provided by social networks.  相似文献   

Ore and Alteration Types of the Gold and Copper Mineralization in the Lascogon Project, Surigao del Norte, Mindanao Island, Philippines     

Jonelle Nikolai Crisostomo    Jeddalyn Parian    Daizo Ishiyama    Redempta Baluda    Sonia Eguia    Jocelyn Galapon    Gerry Comia    Jessie Segura    Maureen Laroco    Noel Oliveros  Victor B. Maglambayan 《Resource Geology》2007,57(2):241-247

Two ore and three alteration types were identified in the Lascogon Project of Philex Gold Philippines, in Surigao del Norte, Mindanao Island, Philippines. The jasperoid ore is the host to the Carlin‐like gold mineralization in the Lascogon and Danao prospects. The ore occurs in a decalcified and silicified horizon, with minor chlorite and goethite, stibnite, pyrite and quartz crystals ranging from cryptocrystalline to botryoidal. The stringer–stockwork type Cu‐Au mineralization in the Suyoc prospect is hosted in argillized andesitic rocks of the Mabuhay Formation. The primary ore minerals are chalcopyrite with minor amounts of sphalerite. The alteration types identified are propylitic alteration, argillic alteration and silicification. The propylitized basaltic and andesitic flows of the Bacuag Formation bound the jasperoid mineralization in the Lascogon prospect. Stratigraphically, the relationship between propylitized basalts and stringer–stockwork Cu‐Au is not clear but a lateral change can be inferred from jasperoid in the center and stringer–stockwork towards the east.  相似文献   

On the use of NOAA's storm surge model,SLOSH, in managing coastal hazards — the experience in Puerto Rico     

Aurelio Mercado 《Natural Hazards》1994,10(3):235-246

A numerical-dynamic, tropical storm surge model, SLOSH (Sea, Land, and Overland Surges from Hurricanes), was originally developed for real-time forecasting of hurricane storm surges on continental shelves, across inland water bodies and along coastlines and for inland routing of water -either from the sea or from inland water bodies. The model is two-dimensional, covering water bodies and inundated terrain. In the present version available at the University of Puerto Rico a curvilinear, polar coordinate grid scheme is used. The grid cells are approximately 3.2 × 3.2 km in size.The model has been used in a revision of all coastal Flood Insurance Rate Maps (FIRM) for Puerto Rico and the U.S. Virgin Islands, and in hurricane evacuation studies. The FIRM's, since they are based on the 100 year stillwater elevation, are also used by the state Planning Board for regulatory purposes. The hurricane evacuation studies are used by emergency planners and personnel to assign shelters, escape routes, and delimit coastal zones that need to be evacuated during a hurricane threat.Recently, the acquisition of data from hurricane Hugo has allowed the first comparison of model results and observations for Puerto Rico and the other islands.  相似文献   

Une Microflore du Barrémien dans la Province de Valencia,Espagne     

J. Doubinger  J.R. Mas 《Cretaceous Research》1981,2(1):51-64

A Barremian microflora is recorded in the terrigenous facies (Weald) of the Lower Cretaceous in the northern region of the Province of Valencia (Spain), these beds have been poorly dated up to now due to the absence of fossils. The Villar del Arzobispo microflora correspond unquestionably to the Barremian-Aptien period, but the numerical importance of derived forms from the Jurassic, the remarkable variety of forms of Cicatricosisporites, and the rareness of pollen of Angiosperms, indicate a Barremian age to be more likely.This discovery permits us to establish the stratigraphical relationship of this terrigenousfacies of Villar del Arzobispo with the dated “Weald” of other areas of the Iberian Chain and to give a complete chrono-stratigraphical interpretation to the different litho-stratigraphical units that constitute the Lower Cretaceous of this region.  相似文献   

Organic fades in Recent sediments of carbonate platforms: Southwestern Puerto Rico and Northern Belize     

Janina Rafalska-Bloch  Robert Cunningham  Jr 《Organic Geochemistry》1986,10(4-6)

Our organic facies model of a platform environment is based on the analysis of (1) total organic carbon, (2) visual protokerogen types and hydrogen indices of the sediments, (3) sediment mineralogy and grain size, and (4) reef patterns, water circulation, and relief of the adjacent land.TOC values are lowest on reefs and outer platforms (0.2%); intermediate in sediments fringing carbonate islands (0.5–2.0%), on sea-grass meadows (0.5–0.7%), and in forereef lagoons (0.1–0.7%); highest in inner platform lagoons (0.5–5.0%) and mangrove swamps (2.7–3.5%). Paniculate organic matter comprises structured terrestrial, marine, and amorphous types. On average, terrestrial material accounts for 28% of OM in Puerto Rico and 12% in Belize. The mean hydrogen index of the sediment is 355 (mg hydrocarbons/g TOC) in Puerto Rico and 719 in Belize.This study indicates that TOC values are mainly related to platform subenvironment, while OM types are controlled by distance from the shoreline. Organic facies dominated by structural terrestrial OM occur closer to the shore, whereas toward the shelf margin marine and amorphous OM contents increase.  相似文献   

Fault kinematics of the Magallanes-Fagnano fault system,southern Chile; an example of diffuse strain and sinistral transtension along a continental transform margin     

《Journal of Structural Geology》2016

A system of left-lateral faults that separates the South American and Scotia plates, known as the Magallanes-Fagnano fault system, defines the modern tectonic setting of the southernmost Andes and is superimposed on the Late Cretaceous – Paleogene Patagonian fold-thrust belt. Fault kinematic data and crosscutting relationships from populations of thrust, strike-slip and normal faults from Peninsula Brunswick adjacent to the Magallanes-Fagnano fault system, presented herein, show kinematic and temporal relationships between thrust faults and sets of younger strike-slip and normal faults. Thrust fault kinematics are homogeneous in the study area and record subhorizontal northeast-directed shortening. Strike-slip faults record east—northeast-directed horizontal shortening, west—northwest-directed horizontal extension and form Riedel and P-shear geometries compatible with left-lateral slip on the main splay of the Magallanes-Fagnano fault system. Normal faults record north-south trending extension that is compatible with the strike-slip faults. The study area occurs in a releasing step-over between overlapping segments of the Magallanes-Fagnano fault system, which localized on antecedent sutures between basement terranes with differing geological origin. Results are consistent with regional tectonic models that suggest sinistral shearing and transtension in the southernmost Andes was contemporaneous with the onset of seafloor spreading in the Western Scotia Sea during the Early Miocene.  相似文献