Westernmost Section Research Articles

Distribution and enrichment of rare metal elements in the basement rocks of South China: Controls on rare-metal mineralization

The southeastern part of the South China Block (SCB) is composed of the Nanling-Yunkai and Wuyi terranes and the Jiangnan Orogenic Belt (JOB), of which the Nanling and the JOB are two world-famous rare-metal metallogenic belts. Rare-metal deposits in both areas are closely associated with crustally-derived granites. However, rare-metal abundances and enrichment mechanisms in Precambrian basement rocks, which probably are sources of the ore-forming granites in the SCB, have not been well understood. Bulk compositions of more than 800 basement rock samples are used to unravel the abundances, variation and enrichment mechanism of the rare-metal elements in Precambrian basement rocks of the SCB and their genetic links with rare-metal mineralization. The basement meta-sedimentary rocks of the westernmost section of the JOB have the highest Sn (10.2 ppm), W (7.7 ppm), Be (3.46 ppm) and Cs (17.1 ppm) abundances, whereas those of the eastern JOB have low Sn (2.4–3.2 ppm), W (1.2–2.1 ppm), Nb (12.9–13.9 ppm) and Be (2.22–2.34 ppm), but relatively high Li (53.3–57.0 ppm) contents. The eastern Nanling basement rocks show high Sn (4.5 ppm), W (3.0 ppm) and U (3.67 ppm) relative to upper continental crust (UCC), similar to the western Nanling basements (4.2 ppm, 3.0 ppm and 4.03 ppm, respectively), but have significantly higher Rb/Sr, Li, Be, Cs and lower CaO/Na2O and Ba than the western Nanling basements, implying the presence of more meta-pelitic rocks in the eastern Nanling basements. The Wuyi terrane is characterized by low rare-metal abundances, e.g Sn (2.1 ppm), W (1.3 ppm), Cs (5.7 ppm) and Li (36.4 ppm). Rare-metal enrichment mechanisms are also distinct in the basement rocks of different terranes of the SCB. Four types of enrichment mechanism are identified: magmatic recycling, chemical weathering, source enrichment and alternative redox depositional environments. The enrichment of Sn, W, Cs and Be in the westernmost basement of the JOB is attributed to a higher proportion of old and multi-cycled materials and alternating depositional environments, and the enrichment of Sn, W, REE and U in the Nanling basement is ascribed to the higher proportion of recycled detritus and an enriched source. Chemical weathering (clay adsorption) is an important initial enrichment mechanism in the eastern JOB basement. Comparisons of rare-metal mineralization in the SCB with the basement compositions suggest that rare-metal mineralization of the granites is not only related to the rare-metal contents of the source, but also is closely related to the lithology of the source. Stronger W mineralization in the eastern JOB and eastern Nanling than in their western parts is probably related to their more pelite-rich basements.

Age, provenance and geological significance of (meta)–sedimentary rocks in the Yitong–Gongzhuling area, NE China: Constraints from zircon U–Pb geochronology

The Permo–Triassic was a crucial interval for the Changchun–Yanji suture zone in NE China since it witnessed the late–stage tectonic evolution of the Paleo–Asian Ocean (PAO). Thus, provenance analysis of Triassic sedimentary rocks in this region can shed light on the eventual closure process of the PAO. In this study, we carried out petrological, geochemical, and detrital zircon U–Pb geochronological research on two (meta)–sedimentary rocks from the Yitong–Gongzhuling area located in the westernmost section of the Changchun–Yanji suture zone. LA–ICP–MS U–Pb ages of detrital zircons from the two samples indicate a middle Triassic maximum depositional age (~ 240 Ma). The two samples present a most significant Permo–Triassic (299–240 Ma) detrital zircon population that corresponds to the multi–phase subduction and collision–related magmatism along the Changchun–Yanji suture zone. In addition, a late Silurian–early Devonian (429–390 Ma) detrital zircon population is also present and presumably fed from a pre–existing accreted arc terrane along the northern margin of the North China Craton (NCC). In contrast to some previously reported Permo–Triassic sedimentary rocks in adjacent areas, our new results show an absence of ~ 2.5 and ~ 1.8 Ga ages characteristic of NCC magmatism or metamorphism. The results imply that the Yitong–Gongzhuling area probably has a higher relief than the adjacent area during the middle Triassic, preventing the deposition of materials from the NCC to the south. This is further evidenced by the proximal orogenic source, short–distance transportation, and rapid accumulation for the studied samples as indicated by the subhedral to anhedral and poor roundness morphology of detrital zircons. The inferred regional uplift was hypothesized to be caused by the continued transpression during the PAO final closure based on the widely distribute early–middle Triassic syn–collisional granitic rocks along the Changchun–Yanji suture zone.

Los poblados históricos del área de frontera en la naciente del Río Mendoza

Los pueblos de montaña que jalonan el alto valle del río Mendoza, en la provincia homónima del centro oeste de Argentina, son testimonio de la modernidad finisecular desde su aparición en el contexto de implantación del Ferrocarril Trasandino, a fines del siglo XIX. Su presencia en el itinerario cordillerano fue fundamental dado que facilitaron el comercio y el transporte, en el tramo más occidental de la ruta que vincula Buenos Aires con las ciudades de Santiago y Valparaíso del vecino país de Chile. Al estar emplazados en estrecha relación con el río Mendoza, y en un soporte geográfico de características singulares; actuaron como estructurantes del territorio, con una disposición sistémica que definió al territorio fronterizo hasta mediados del siglo XX. El problema que motiva este trabajo se basa en la detección de una vacancia referida a la lectura integral de bienes culturales, ligados al tramo superior del río Mendoza. Los aportes efectuados hasta el momento son fragmentarios, sobre todo en relación con los bienes que consolidaron el territorio de la cordillera mendocina; a nivel turístico, vial y de servicios. Mediante el análisis descriptivo-explicativo de cuatro poblados históricos se pretende llenar el vacío detectado y comprender el rol fundamental que desempeñaron en el proceso de ocupación paulatina del territorio de alta montaña, iniciado en el tiempo de la modernidad.

Genesis and geodynamic process of early Cretaceous intermediate–felsic batholith within the Chem Co zone, western Qiangtang and implications for Bangong–Nujiang Tethyan Ocean subduction

The complex evolutionary history of collision-related suture zones in the western Qiangtang is poorly understood, due to the lack of pivotal magmatic and tectonic records. The Chem Co intermediate-felsic batholith is situated in the westernmost section of Qiangtang, where it intruded into the Upper Paleozoic metamorphic sedimentary series and was cut by Late-Cenozoic active normal faults. Here, we present evidence from field observations, geochemistry, zircon UPb and Hf isotopes, and mica 40Ar39Ar analysis of these granitoid rocks. Zircon UPb ages ranging from 107.3 ± 1.4 to 123.7 ± 1.7 Ma reveal that this magmatism initiated in the Early Cretaceous. Mica 40Ar39Ar yield plateau ages from 99 to 118 Ma suggest rapid emplacement into the cold crust without disturbance by subsequent >320 °C tectono-thermal events. Major element geochemistry shows these granitic rocks are enriched in Al, depleted in Ca, lie mostly within the high–K calc–alkaline series and have peraluminous features. Mineral modes that lack amphibole but contain muscovite, together with the geochemical characteristics, indicate an S–type granite affinity. Furthermore, the rocks are strongly enriched in large-ion lithophile elements (LILE) and light rare earth elements (LREE), and are moderately to strongly depleted in high field strength elements (HFSE) and heavy rare earth elements (HREE), thus indicating typical characteristics of arc-related magmatic rocks. Considering the petrogenesis, geochemical features, zircon UPb ages, negative zircon εHf(t) values, similarity with the southwestern Qiangtang intrusions, and the geological setting, we conclude that the Chem Co granite was derived from the anatexis of crustal lithosphere through a “soft” collision associated with the continuing northwards subduction of the Bangong–Nujiang Tethyan (BNT) Ocean. We propose that the final closure and termination of the western segment of the BNT Ocean was completed later than 107 Ma.

Tourmaline geochemistry and boron isotopic variations as a guide to fluid evolution in the Qiman Tagh W–Sn belt, East Kunlun, China

The Qiman Tagh W–Sn belt lies in the westernmost section of the East Kunlun Orogen, NW China, and is associated with early Paleozoic monzogranites, tourmaline is present throughout this belt. In this paper we report chemical and boron isotopic compositions of tourmaline from wall rocks, monzogranites, and quartz veins within the belt, for studying the evolution of ore-forming fluids. Tourmaline crystals hosted in the monzogranite and wall rocks belong to the alkali group, while those hosted in quartz veins belong to both the alkali and X-site vacancy groups. Tourmaline in the walk rocks lies within the schorl–dravite series and becomes increasingly schorlitic in the monzogranite and quartz veins. Detrital tourmaline in the wall rocks is commonly both optically and chemically zoned, with cores being enriched in Mg compared with the rims. In the Al–Fe–Mg and Ca–Fe–Mg diagrams, tourmaline from the wall rocks plots in the fields of Al-saturated and Ca-poor metapelite, and extends into the field of Li-poor granites, while those from the monzogranite and quartz veins lie within the field of Li-poor granites. Compositional substitution is best represented by the MgFe−1, Al(NaR)−1, and AlO(Fe(OH))−1 exchange vectors. A wider range of δ11B values from −11.1‰ to −7.1‰ is observed in the wall-rock tourmaline crystals, the B isotopic values combining with elemental diagrams indicate a source of metasediments without marine evaporates for the wall rocks in the Qiman Tagh belt. The δ11B values of monzogranite-hosted tourmaline range from −10.7‰ and −9.2‰, corresponding to the continental crust sediments, and indicate a possible connection between the wall rocks and the monzogranite. The overlap in δ11B values between wall rocks and monzogranite implies that a transfer of δ11B values by anataxis with little isotopic fractionation between tourmaline and melts. Tourmaline crystals from quartz veins have δ11B values between −11.0‰ and −9.6‰, combining with the elemental diagrams and geological features, thus indicating a common granite-derived source for the quartz veins and little B isotopic fractionation occurred. Tourmalinite in the wall rocks was formed by metasomatism by a granite-derived hydrothermal fluid, as confirmed by the compositional and geological features. Therefore, we propose a single B-rich sedimentary source in the Qiman Tagh belt, and little boron isotopic fractionation occurred during systematic fluid evolution from the wall rocks, through monzogranite, to quartz veins and tourmalinite.

Sedimentary record of subsidence pulse at the Triassic/Jurassic boundary interval in the Slovenian Basin (eastern Southern Alps)

AbstractIn the Alpine Realm the Early Jurassic is characterized by the disintegration and partial drowning of vast platform areas. In the eastern part of the Southern Alps (present-day NW Slovenia), the Julian Carbonate Platform and the adjacent, E-W extending Slovenian Basin underwent partial disintegration, drowning and deepening from the Pliensbachian on, whereas only nominal environmental changes developed on the large Dinaric (Friuli, Adriatic) Carbonate Platform to the south (structurally part of the Dinarides). These events, however, were preceded by an earlier - and as yet undocumented extensional event - that took place near the Triassic/Jurassic boundary. This paper provides evidence of an accelerated subsidence from four selected areas within the Slovenian Basin, which show a trend of eastwardly-decreasing deformation. In the westernmost (Mrzli vrh) section - the Upper Triassic platform-margin - massive dolomite is overlain by the earliest Jurassic toe-of-slope carbonate resediments and further, by basin-plain micritic limestone. Further east (Perbla and Liščak sections) the Triassic-Jurassic transition interval is marked by an increase in resedimented carbonates. We relate this to the increasing inclination and segmentation of the slope and adjacent basin floor. The easternmost (Mt. Porezen) area shows a rather monotonous, latest Triassic-Early Jurassic basinal sedimentation. However, changes in the thickness of the Hettangian-Pliensbachian Krikov Formation point to a tilting of tectonic blocks within the basin area. Lateral facies changes at the base of the formation indicate that the tilting occurred at and/or shortly after the Triassic/Jurassic boundary

Scale and Subnational Resource Management: Transnational Initiatives in the Salish Sea Region

AbstractTransboundary water resources are very challenging to manage, generating numerous unresolved management issues. North America possesses two different spatial contexts in which transboundary water resource management issues exist, the arid U.S.–Mexico border region and the humid U.S.–Canada border region. Past work on the U.S.–Mexico border has explored a range of institutional arrangements by which resources are managed, with a special focus on both existing and new institutions and how the locus of policy formulation may vary across scale. In this article, I explore water resource issues in the U.S.–Canadian transboundary context through a comparative examination of management frameworks in the westernmost section on the U.S.–Canada border. Specifically, I examine the Cascadia Corridor region within which the Salish Sea and smaller nested watersheds lie, exploring how concepts of devolution, regionalization, subnational participation, and spatial scale have unfolded in transboundary management efforts in the region.

Shallow Rupture of the 2011 Tarlay Earthquake (Mw 6.8), Eastern Myanmar

We use L‐band Advanced Land Observation Satellite PALSAR data to infer the distribution of subsurface fault slip during the Tarlay earthquake (M_w 6.8) in eastern Myanmar. We find the total length of surface rupture is approximately 30 km, with nearly 2 m maximum surface offset along the westernmost section of the Nam Ma fault (the Tarlay segment). Finite‐fault inversions constrained by Interferometric Synthetic Aperture Radar (InSAR) and pixel‐tracking data suggest that fault slip is concentrated within the upper 10 km of the crust. Maximum slip exceeds 4 m at a depth between 3 and 5 km. Comparison between field measurements and near‐fault deformation obtained from the InSAR range‐offset result suggests about 10%–80% of displacement occurred within a 1 km wide zone off the main surface fault trace. This off‐fault deformation may explain the shallow slip deficit that we observed during this earthquake. We estimate a recurrence interval for Tarlay‐like events to be 1600–6500 yrs at this section of the Nam Ma fault. A detailed paleoseismological study is essential to clarify the slip behavior and the earthquake recurrence interval of the Nam Ma fault.

Two-station measurement of Rayleigh-wave phase velocities for the Huatung basin, the westernmost Philippine Sea, with OBS: implications for regional tectonics

SUMMARY A broad-band ocean-bottom seismometer (OBS) deployed ∼180 km east of Taiwan provides a first glimpse into the upper mantle beneath the westernmost section of the Philippine Sea or the Huatung basin (HB). We measured interstation phase velocities of Rayleigh waves between the OBS and stations on the eastern coast of Taiwan. The phase velocities show smooth variations from 3.8 to 3.9 km s −1 for periods of 25–40 s. In this short period range, phase velocities are comparable to those characterizing the 15–30 Ma Parece-Vela basin of the Philippine Sea. Modelling of the finite-frequency effect proves the validity of the measurement for the average HB. The shear-wave velocity models inverted from the 25 to 40 s dispersion show a velocity at lithospheric depths about 0.1 km s −1 lower than that of the west Philippine Sea, which agrees with the age effect derived from the Pacific pure-path model. Inversions incorporating the less reliable data above 40 s yield a shear velocity <4.0 km s −1 below 150 km, an unrealistic value even for a hotspot plume environment. The seismological evidence, together with the correlation in seafloor depth, suggests that the HB and the Parece-Vela basin may have a similar age. This is at odds with the previous geochronological study suggesting an early-Cretaceous age for the HB. Thermal rejuvenation of the lithosphere was examined as a potential solution to reconciling the two age models.

Using the biogeographical distribution and diversity of seaweed species to test the efficacy of marine protected areas in the warm‐temperate Agulhas Marine Province, South Africa

AbstractAim To study the siting of marine protected areas (MPAs) with respect to the biogeographical distribution of seaweeds within the Agulhas Marine Province and to assess the effectiveness of current MPAs in including (conserving) seaweeds of the South African south coast.Location South Africa – the south coast between Cape Agulhas and the Eastern Cape/Kwazulu‐Natal border, and eight MPAs within that area.Methods We used interpolated seaweed distribution records from all available sources, in 50‐km coastal sections. Cluster analysis (Jaccard Average Linkage) of species presence/absence data provided measures of similarity between coastal sections and between MPAs. Complementarity analyses identified the sequence of ‘importance’ of sections/MPAs for conserving seaweed species.Results Species presence/absence data indicated two main groups, representing western (cooler water) and eastern (warmer water) biogeographical divisions, as well as several biogeographical subdivisions within each of these groups. Complementarity analysis yielded a sequence of ‘importance’ of coastal sections (in terms of the highest number of species included) that began with a section just east of central in the Agulhas Marine Province, around Port Alfred, where there is no MPA. This was followed by the easternmost section (warmest water), which contains the Pondoland MPA, and then by the westernmost (coolest water) section, containing the De Hoop MPA. Similar analysis of the actual species collected in MPAs showed a generally similar pattern.Main conclusions Seven current MPAs and one proposed coastal MPA in the Agulhas Marine Province appear to be well distributed and well sited to include (conserve) the full biogeographical range of seaweeds. However, if further MPAs are to be considered, the Port Alfred area is recommended for improved conservation. This study did not examine estuaries, which may require improved conservation efforts. Seaweed distribution data, which are often relatively complete, offer a good tool for planning the siting of coastal MPAs.

From the Guanahatabey to the Archaic of Puerto Rico: The Nonevident Evidence

Some of the early Spanish chronicles make reference to the presence of cave dwellers inhabiting the westernmost section of Cuba as well as the Guacayarima Peninsula in southwestern Haiti. These people, who supposedly lived marginal to Taino society, were named the Guanahatabey or Ciboney culture. The different descriptions of those groups shared elements that were later adopted uncritically in the construction of the social and cultural aspects of the so-called archaic culture tradition of Puerto Rico. Although half a millennium later the tendency to assign every aceramic deposit to the Ciboney or Guanahatabey culture has been overcome, most of the notions implicit in these descriptions remain current in the generalized vision of these societies. In this work, I analyze the implications that these early accounts have had on the development of our perception of the archaic culture of Puerto Rico and contrast them against the archaeological data generated thus far, which tend to indicate a much more complex scenario than that originally proposed.

Records of and Observations on Tanaidaceans (Peracarida) from Shallow Waters of the Caribbean Coast of Mexico

[As in other tropical areas, the tanaidacean fauna of the western Caribbean Sea remains poorly known. Our study is based on the examination of several families of Tanaidacea from samples collected at 30 sites in a variety of shallow-water marine habitats along the Mexican Caribbean coast, located on the westernmost section of the Caribbean Basin. Up to 13 species belonging to seven families and 11 genera were identified. Of these species, four have been previously recorded from the Caribbean coast of Mexico and nine constitute new regional records. Nine species have been known to occur in the Caribbean Basin and four species, Hexapleomera robusta (Moore), Leptochelia dubia (Kroyer), Sinelobus stanfordi (Richardson), and Zeuxo kurilensis (Kussakin & Tzareva) are widely distributed forms, occurring in two or more oceans. Taxonomic and comparative comments are provided for some species recorded in the surveyed area. The male of Pseudotanais (Akanthinotanais) mortenseni Sieg is recognized and documented for the first time, based on the only specimen found., As in other tropical areas, the tanaidacean fauna of the western Caribbean Sea remains poorly known. Our study is based on the examination of several families of Tanaidacea from samples collected at 30 sites in a variety of shallow-water marine habitats along the Mexican Caribbean coast, located on the westernmost section of the Caribbean Basin. Up to 13 species belonging to seven families and 11 genera were identified. Of these species, four have been previously recorded from the Caribbean coast of Mexico and nine constitute new regional records. Nine species have been known to occur in the Caribbean Basin and four species, Hexapleomera robusta (Moore), Leptochelia dubia (Kroyer), Sinelobus stanfordi (Richardson), and Zeuxo kurilensis (Kussakin & Tzareva) are widely distributed forms, occurring in two or more oceans. Taxonomic and comparative comments are provided for some species recorded in the surveyed area. The male of Pseudotanais (Akanthinotanais) mortenseni Sieg is recognized and documented for the first time, based on the only specimen found.]

Tonga Ridge and Lau Basin crustal structure from seismic refraction data

The crustal structure across the Tonga‐Lau arc‐back arc system from the Lau Ridge to the Pacific Plate (178°–170°W, 18°19°S) is modeled, using data from an 840‐km‐long air gun refraction line over 19 ocean bottom seismometers and one land station. The data reveal that the Pacific Plate crust is 5.5 km thick, with a velocity structure similar to that found at the present‐day East Pacific Rise (EPR). Beneath Tonga Ridge, an intermediate velocity layer (6–7 km/s) is up to 7.5 km thick and has a velocity‐depth distribution similar to andesitic rocks found in continental crust. The crust is abnormally thin (4 km) at the boundary between the Tonga Ridge and the Lau Basin. At the east end of Lau Basin, the crust is 5.5–6.5 km thick and resembles crust formed at the EPR except for a thicker sheeted‐dike section (2–3 km) and thinner lower crust (2 km). The Lau Basin crust thickens to 7–8 km near the Central Lau Spreading Center (CLSC), mostly through thickening of the lower crust. The crust thickens again to 8.5–9.5 km at 50 km west of the CLSC, mostly through thickening of the midcrust. In the thick westernmost section, the crustal structure is uniform even though one part of this section formed through extension of arc‐type crust while the rest was created at an oceanic spreading center. The relative homogeneity of these rocks suggests that their petrology may be dominated by postemplacement magmatic infilling from a mantle source west of the spreading center.

A 3D gravity model of crustal structure in the Central-Eastern Alpine sector

Assuming as a starting model the pattern of the Moho boundary as interpreted in a recent study on the basis of the available DSS profiles, a preliminary 3D gravity model of the crustal structures in the Central-Eastern Alpine sector is proposed. The aim of the present work is to confirm the seismic results concerning the Moho and to better shape the main discontinuities in the intermediate and upper crust, where the seismic data are too scattered to allow a reliable interpretation. The gravity field is calculated along twelve cross-sections oriented S-N and crossing the Alpine range from the Padan-Venetian plain to the Bavarian molasse and to the Austrian calcareous Alps. The westernmost section coincides with the European Geotraverse while the easternmost one is positioned at the longitude of about 14ºeast. The assumed density model is very simple (only 6 layers); for each unit the density is maintained constant. The model describes a European mantle dipping southwards underneath an overlapping, uplifted Adriatic mantle. As far as the lower crust is concerned, its top is found at depths between 18 and 28 km, the deepest values being reached in the south-eastern sector; the density appears higher in the Adriatic domain than in the European one and the Adriatic lower crust seems to be deeply indented northwards. The low density surface layers appear very thin in a large area of the northwestern sector, while in the south and southeast their thickness reaches about 10 km. This study must be considered as a complement to the seismic interpretation both as a validation of the model of the deep crust and Moho boundary and as an additional source of information on the upper crust.

A tear fault boundary between the Taiwan orogen and the Ryukyu subduction zone

More than twenty seismic lines were analysed across the intersection of the Taiwan orogen and the Ryukyu arc-forearc system. The main results of this study concern the recognition of two superposed sedimentary basins that were previously unknown. We have named the recent one the Hoping Basin and the older, tectonized one the Suao Basin. The Suao Basin, containing sediments more than 3 km thick, records subsidence of about 3 km on its southwestern portion after being shortened in the direction of plate convergence. On the basis of seismicity, gravity, present-day plate kinematics as well as seismic reflection data, we relate the dramatic subsidence of the Suao Basin to the initiation of a WNW-trending tear fault within the Philippine Sea plate. This tear fault decouples the subducting Philippine Sea plate to the northeast and the apparent overthrusting Philippine Sea plate in the Coastal Range to the southwest. Back-arc rifting may thus occur in the westernmost section of the Okinawa trough above the sinking Philippine Sea slab while lithospheric shortening prevails south of Hualien. As a consequence, the triangular area located southwest of the tear fault, between the Taiwan coastline and the toe of the Yaeyama ridge, no longer belongs to the Ryukyu forearc. It is now passively transported with the non-subducting portion of the Philippine Sea plate. We propose an evolutionary model for the relative chronology of tectono-sedimentary events in this region over the last 5 m.y.

The Alaska Coastal Current: Continuity of transport and forcing

Current moorings were deployed on the continental shelf at 13 locations in the northwest Gulf of Alaska. They measured the Alaska Coastal Current at three positions along the coast during April–October 1991. The strongest currents were in the confined region of Shelikof Strait. Mean daily transport was as large as 2.5×106 m3 s−1. Mean transport over the 6‐month period ranged from 0.85×106 m3 s−1 at the easternmost line (off Gore Point) to 0.64×106 m3 s1− at the westernmost section (Shelikof Strait), indicating significant transport to the south of Kodiak Island. The transports were well correlated (r &gt; 0.8) and in phase with each other and were also correlated with wind (r ∼ 0.6). Data suggest that in Shelikof Strait and off Gore Point, baroclinic flow is ∼75% and &lt;40%, respectively, of total transport.

Depositional Environments of Painted Rock Sandstone Member of Miocene Vaqueros Formation in Eastern Caliente Range, San Luis Obispo County, California: ABSTRACT

The Painted Rock Sandstone Member of the Miocene Vaqueros Formation in the southeastern Caliente Range, San Luis Obispo County, California, crops out in a narrow band along the anticlinal Caliente Range. The study area is on the eastern flanks of the northwest-trending range. The Painted Rock Sandstone Member is conformably underlain by the Soda Lake Shale Member of the Vaqueros. In the eastern part of the study area, the member is conformably overlain or interfingers with the Oligocene-Miocene Caliente Formation. In the western study area, Painted Rock is conformably overlain by the Miocene Monterey Formation. The Painted Rock Member thickens rapidly to the west with measured thickness ranging from 130 m in the easternmost section to 1800 m in the westernmost and type section. The member generally coarsens upward from interbedded mudstone and fossiliferous, laminated, fine-grained sandstones to cyclical couplets of fossiliferous, medium-grained, cross-bedded sandstones underlying laminated, medium-grained sandstones and local conglomerates. Interspersed within the member is a medium to coarse-grained, structureless sandstone. The Painted Rock generally coarsens to the east, except for almost completely conglomeratic outcrops in a central section. The Painted Rock sequence represents a gradual shoaling from lower-shoreface environments (fine sands and mudstones), to shoreface and foreshoremore » deposits (sandy couplets). The structureless sandstone may fit in this sequence or it may record a subaqueous part of the nearby Caliente delta. The conglomerate section represents a basin-feeding channel. The anomalously thick type section coupled with the conformably overlying deep-marine Monterey Formation records rapid basin subsidence in the western study area.« less

The Fate of Amphibians and Reptiles in a Suburban Area

Between 1949 and 1958, two species of salamanders, six species of anurans, six species of turtles and seven species of snakes were recorded from a suburban area on the edge of Indianapo- lis, Indiana. Most were terrestrial or semiaquatic species of broad ecological tolerance. At least 11 species bred within the area during this period. During 1963 and 1964 only two species of anurans, one species of turtle and four species of snakes were recorded, and there was no evidence of amphibian breeding. Modification of aquatic habi- tat appears to have been the most important factor in reducing the number of species inhabiting the area. This report is an informal summary of observations on amphibians and rep- tiles in Valley View, a suburban area at the north edge of Indianapolis, Indiana, from February, 1949 through May, 1958, and from November, 1962 through Aug- ust, 1964. Between 1949 and 1954, a fair census of the herpetofauna was made largely through the enthusiastic participation of our younger neighbors, especially David Trusty and Fred Grannan. Subsequent to 1954, there was less collecting, but observations continued throughout our period of residence. I gratefully acknow- ledge the invaluable help of my wife, Madge, and my daughters, Brooks, April and Holly, and my neighbors for their aid in compiling the information summarized here. The area where most of these observations were made is about a mile northeast of Broad Ripple community at the east edge of the White River flood plain. It is roughly trapezoidal in shape measuring 0. 3 miles from east to west, 0. 25 miles north to south along the west border and 0. 4 miles along the east border. The north boundary is Bailey Creek, a small stream that flows directly into White River about 0. 3 miles west of the area. The south boundary is Hamp's Ditch draining a tract of formerly swampy woodland into White River. The westernmost section of the ditch marks the north edge of Broad Ripple Park. Keystone Avenue and Evan- ston Avenue form the east and west boundaries respectively. In 1949 both were thoroughfares of approximately equal width carrying a comparable volume of traf- fic; by 1962 Keystone Avenue had become a major, multilane traffic artery. Streets within the area carry a comparatively light load of local traffic. Development of the area as a residential suburb began about 1940, largely ceased during World War II and was resumed in 1947. Today the area is entirely residential; in 1949 it included several unimproved lots and part of a corn field bordered by trees and bushes. Undergrowth and cover in the form of logs and rubbish were fairly abun- dant along Bailey Creek and Hamp's Ditch in 1949 but had almost vanished by 1964. The area was probably originally forested. Native hardwoods of considerable size remain along with introduced evergreens and other ornamentals. Until 1951 a small stock pond was located just outside the area. Traces of original vegetation ob- served in 1949 indicated that the area between 65th Street and Hamp's Ditch may have been open and marshy. In 1949 Bailey Creek presented the appearance of many central Indiana farm- land streams. The banks were gently sloping and covered with willows and other

The Organization and Functions of the Ragbenle Society of the Temne

Opening ParagraphThe Temne of the Northern Province of Sierra Leone are second only to the Mende in the Protectorate, numbering over half a million and inhabiting some 10,500 square miles of land. In general, they are culturally similar to their neighbours, especially in their possession of a number of societies, some secret, some not, which play integral roles in their lives. Of the societies found in this westernmost section of the Guinea Coast area, the Bundu or Sande for women and the Poro for men have been described by various writers for a number of groups. The emphasis placed on these two societies in the literature is justifiable in view of their multi-tribal geographic distribution, their general membership embracing most of the adult population and much of the adolescent segment in the groups where they are found, and the important functions they serve. In addition, however, there are a number of societies in this general area which, although they have a more restricted area distribution and less general membership, nevertheless also serve important functions for one or more groups. Such a society is the Ragbenle, also known as Maneke, which is centred in the eastern section of Temne country, where it is closely connected with the chiefs, particularly in conducting the ceremonies associated with their death, burial, selection, instruction, and installation, and, in addition, purifies violators of incest prohibitions, heals the chief and anyone else seeking help, divines witches, and provides other supernatural services. The purpose of this paper is to consider the membership of the society in terms of both supernatural and human members, and its functions in various aspects of Temne life.