Granitic Rock Outcrops Research Articles

A new type of clay-Li deposit: Fault-controlled hydrothermal alteration in southern Hubei Province, China

Clay-Li deposits are among the major Li deposits in the world and occur mainly in sedimentary and/or volcanic-sedimentary strata. The Li orebodies are generally stratiform and stratibound, and Li is mainly hosted in various clay minerals. Here, we report a new type of clay-Li deposit that occurs along fault zones developed in metasedimentary rocks with significant alteration, and Li is also hosted in clay minerals in the Jinyinshan area in Xianning, southern Hubei Province, China. The study area has no granitic rock outcrops, but approximately 15 km south is the Mufushan granite batholith, where large-scale rare metal mineralization, such as Li, Be, Nb and Ta granitic pegmatites, developed in the internal and outer contact zones of the granite batholith. In this study, high-Li clay minerals, including chlorite, kaolinite and smectite, were identified. The enrichment of Li is closely related to hydrothermal activity along the F9 fault in the region. Hydrothermal apatite coexisting with Li-clay in the orebody along the fault zone yielded an in situ U–Pb age of 135.2 ± 13.9 Ma, which is in good agreement with the ages of granites and Li-pegmatites around the Mufushan batholith. Petrographic, geochemical, and chronological evidence suggests that the ore-forming fluids and Li were likely sourced from the Mufushan granite batholith or a similar blind granite at the depth of the study area; that is, the granite-derived ore-forming fluids can travel long distances along fault zones, and during this pathway, Li from the metasedimentary rocks (i.e., the Lengjiaxi Group) may also have been leached by the fluids and contributed to the Li mineralization in the Jinyinshan clay-Li deposit. The close spatial relationships among different clay minerals indicate that fluid physical–chemical conditions (changes in temperature) may play a crucial role in controlling the formation of Li-rich clay minerals. Our study indicates that the Mufushan area has great potential for hydrothermal clay-Li mineralization occurring in the Lengjiaxi Group metasedimentary rocks around the Mufushan batholith.

Сосновые (Pinus sylvestris) леса и редколесья Северо-Западного Приладожья

Сосновые (Pinus sylvestris) леса и редколесья Северо-Западного Приладожья

Geotourism Route through Trás-os-Montes e Alto Douro University (Vila Real, Galicia-North Portugal Euroregion): a Space of Public Outreach of Geology

Geoconservation, geotourism and geodiversity are concepts that should be taught at all educational levels. The entire society should preserve the natural resources in a sustainable way. Geological processes and quarrying created and still creates cultural heritage in landscapes, villages and cities worldwide. Rock outcrops, historical quarries, forms of extraction and buildings built with stones are a heritage that should safeguard. This work details a geotourism route that would bring new life to Tras-os-Montes e Alto Douro University (UTAD) campus. The proposed route connects a historical quarry located in the UTAD campus with the main church built with its granite and different rock outcrops that show the geological history of the city of Vila Real (Portugal). It envisages a three-points of interest tour from the Fernando Real Geology Museum (UTAD) to a church built with Prezandães granite from Folhadela.

Control Structure On Damage Zone and Fault Plane to Geometry Of Quartz Veins and Calcite In Muaradua Ogan Komering Ulu Selatan, South Sumatra, Indonesia

Geological mapping was carried out on the Gilas and Malau rivers in the Muaradua area, South Ogan Komering Ulu Regency, South Sumatra by observing the presence of joints, faults, and veins in the granite and phyllite rock outcrops of the Tarap Formation. Research on pattern geometry and vein type in the crushing zone is focused on measuring the direction (trend) of veins and joints. The measurement results are then analyzed to obtain a general pattern of quartz and calcite veins so that the orientation of their development can be known. The method used in this study is in the form of determining the orientation and geometry of the veins based on classifications that refer to several studies, then an analysis is carried out using DemNAS data to determine the general direction of the straightness pattern of the study area. The quartz veins that developed in the study area have an extensional fracture type with the geometry found in the form of isolated, abutting, cutting, mutually-cutting, and crosscutting. The veins that develop in the research area are relatively north-south and west-east and indicated the presence of a fault and traces of deformation that occurred in the study area. With the help of veins and joints found in the study area, it is possible to determine the structural control of the presence of a crushing zone in the fault plane.

Novidades do estrato herbáceo em uma região chave para a conservação da Amazônia Meridional

Abstract The contribution of the herbaceous stratum to tropical plant diversity is considerable, however this component remains undersampled. We investigated floristic, structural, ecological and conservation issues concerning the herbaceous component of a seasonal deciduous forest associated with granitic rock outcrops in the Cristalino Region, a key area for biodiversity conservation in the Brazilian Amazon. We installed a permanent plot of 1 ha, allocating 10 transect-lines of 20 m each. We identified the sampled individuals, measured height and projection, and verified cover and frequency per species, genera and family. We recorded 86 species, 62 genera and 25 families, with Orchidaceae being the family with the highest species richness. Among the 26 new species added to Cristalino Flora, we included Philodendron deflexum Poepp. ex Schott and Griffinia nocturna Ravenna, the latter ‘Critically Endangered’. Furthermore, the occurrence of G. nocturna in an Amazonian forest matrix is a novelty in this study. The estimate of species diversity according to Shannon-Wiener (H’) was 2.43 nats.ind.-1 (equivalent to 11.37 ± 0.90 IC95% equally common species), and according to Simpson (1/D), 6.82 (± 0.648 IC95%). The rarefaction and extrapolation curves for the diversity estimates tended to stabilize. Although the vegetation on rock outcrops usually presents a high number of endemic species, this pattern was not found in our study area, which can be explained by its continuous occurrence in the forest matrix. The understory of our study area consists in a mixture of floras, being composed mainly of species from the Amazon and/or Cerrado biomes. In view of the current anthropic pressure faced by the southern Amazon, we reinforce the importance of carrying out inventories of its herbaceous communities, since the risk of species loss is even more alarming when considering present undersampling of this component.

High plant taxonomic beta diversity and functional and phylogenetic convergence between two Neotropical inselbergs

ABSTRACTBackground: Inselbergs (granitic and gneissic rock outcrops) are common elements in the Atlantic Forest and present large taxonomic (TD), functional (FD) and phylogenetic (PD) diversity.Aims: We investigated how plant diversity changed across ecological and biogeographic scales by comparing TD, FD and PD of communities within and between two inselbergs. We expected converging FD and PD but distinct TD between outcrops, because of similar local environmental conditions in inselbergs and the long-term lineage isolation.Methods: We calculated TD, PD and FD, and partitioned diversity into α (each inselberg), β (between inselbergs) and γ (whole sample) components. Phylogenetic signal was estimated for all traits. To link environmental predictors to functional traits a redundancy analysis was run. Variation in TD, FD and PD was analysed by general linear models with patch area and the two inselbergs as predictors.Results: The inselbergs were taxonomically different, but showed convergence in their functional and phylogenetic diversity. The limited retention of phylogenetic signal suggests that different species may converge and respond similarly to environmental variables. Within inselbergs, larger patches displayed higher TD, FD and PD.Conclusions: Seeking conservation strategies for inselbergs is challenging since, despite their functional and phylogenetic similarity, endemic species make individual rock outcrops unique.

The extraordinary botanical diversity of inselbergs in Madagascar

Rabarimanarivo, M.N., B. Ramandimbisoa, N.H. Rakotoarivelo, P.B. Phillipson, S. Andriambololonera, M.W. Callmander & S. Porembski (2019). The extraordinary botanical diversity of inselbergs in Madagascar. Candollea 74: 65–83. In English, English and French abstracts. DOI: http://dx.doi.org/10.15553/c2019v741a8Inselbergs are isolated mountains, mainly granitic or gneissic rock outcrops rising abruptly above surrounding plains. Malagasy inselbergs are often dome-shaped and occur in varying degrees of isolation, but they sometimes form inselberg landscapes, which comprise dozens of individual outcrops. Despite being typical landscape features on Madagascar's high plateau, little data are available on their detailed plant cover. Recent extensive fieldwork, which was conducted between 2010 and 2014, mainly on the central plateau, has resulted in a better knowledge about the floristic composition and habitats of Malagasy inselbergs. The most speciose vascular plant genera were Cynorkis Thouars (18), Cyperus L. (15) and Euphorbia L. (14). Malagasy inselbergs are centres of diversity for succulents (notably species of the genera Aloe L., Euphorbia and Kalanchoe Adans.), carnivorous plants (species of Drosera L. and Utricularia L.) and resurrection plants (notably species of Xerophyta Juss.). The most speciose habitat types were ephemeral flush vegetation and monocotyledonous mats. The latter habitat supports a large number of succulents and resurrection plants. In total 724 taxa out of 338 genera and 107 families have been recorded. Moreover, the variability in floristic composition between different regions is remarkable. Detrimental human impacts include quarrying, grazing, fire and the collection of plants for ornamental purposes (species of Pachypodium Lindl. and Orchidaceae) and as medicine (species of Aloe, Drosera madagascariensis DC., Myrothamnus moschatus (Baill.) Baill.). For the first time, recommendations are made for the conservation of Malagasy inselbergs.

Investigation of Population Structure in the RareAmsonialudovicianaVail (Louisiana Bluestar; Apocynaceae)

Amsonia ludoviciana (Louisiana Bluestar), in the Apocynaceae family, is a rare herbaceous perennial plant species found in the ecotones of granite rock outcrops of Georgia as well as the pine flatwoods in Louisiana, Mississippi, and Texas. This research focused on using fluorescently tagged primers to amplify polymorphic microsatellite loci as a way to characterize the population genetic structure of the rare Louisiana Bluestar in Georgia. We sampled 6 populations across the Georgia range of Louisiana Bluestar. We employed 8 microsatellite loci to detect variation within and among Louisiana Bluestar populations and to detect patterns in population structure and dispersal. Values of the genetic-diversity estimator Gst suggested that the majority of the sampled populations demonstrated moderate genetic similarity. Further, Geneland software indicated the presence of 3 clusters. From our population genetic analyses, it can also be inferred that there is substantial gene flow between populations of Louisiana Bluestar in the state of Georgia.

Three new species of Acalypha (Euphorbiaceae, Acalyphoideae) from Argentina, Bolivia, Brazil and Paraguay

Acalypha chaquensis, A. inselbergensis, and A. pedemontana (Euphorbiaceae: Acalyphoideae) are described as new species, and illustrated with line drawings. A. chaquensis is found in northwestern Paraguay and northern Argentina; A. inselbergensis grows on granitic rock outcrops in Pernambuco State, in Brazil, and A. pedemontana is found in the eastern slope of the Cordillera Oriental of the Bolivian Andes. These species belong to subgenus Acalypha, sections Communes (A. chaquensis and A. pedemontana) and Cuspidatae (A. inselbergensis). Comments on the systematics of the morphologically related species are included.

The xeric side of the Brazilian Atlantic Forest: The forces shaping phylogeographic structure of cacti.

In order to investigate biogeographic influences on xeric biota in the Brazilian Atlantic Forest (BAF), a biodiversity hotspot, we used a monophyletic group including three cactus taxa as a model to perform a phylogeographic study: Cereus fernambucensis subsp. fernambucensis, C. fernambucensis subsp. sericifer, and C. insularis. These cacti are allopatric and grow in xeric habitats along BAF, including isolated granite and gneiss rock outcrops (Inselbergs), sand dune vegetation (Restinga forest), and the rocky shore of an oceanic archipelago (islands of Fernando de Noronha). The nucleotide information from nuclear gene phytochrome C and plastid intergenic spacer trnS‐trnG was used to perform different approaches and statistical analyses, comprising population structure, demographic changes, phylogenetic relationships, and biogeographic reconstruction in both spatial and temporal scales. We recovered four allopatric population groups with highly supported branches in the phylogenetic tree with divergence initiated in the middle Pleistocene: southern distribution of C. fernambucensis subsp. fernambucensis, northern distribution of C. fernambucensis subsp. fernambucensis together with C. insularis, southern distribution of C. fernambucensis subsp. sericifer, and northern distribution of C. fernambucensis subsp. sericifer. Further, the results suggest that genetic diversity of population groups was strongly shaped by an initial colonization event from south to north followed by fragmentation. The phylogenetic pattern found for C. insularis is plausible with peripatric speciation in the archipelago of Fernando de Noronha. To explain the phylogeographic patterns, the putative effects of both climatic and sea level changes as well as neotectonic activity during the Pleistocene are discussed.

Development of 15 SSR polymorphic markers for the endangered Ameroglossum pernambucense Eb. Fischer, S. Vogel & A. V. Lopes (Scrophulariaceae), and cross-transferability in congeneric taxa

Ameroglossum (Scrophulariaceae) is an endemic genus from northeastern Brazil patchily distributed in granitic rock outcrops (inselbergs) with two species described: the endangered A. pernambucense Eb. Fischer, S. Vogel & A. V. Lopes and the narrow endemic A. manoel-felixii L. P. Felix & E. M. Almeida. We developed 15 polymorphic nuclear microsatellite markers for A. pernambucense using pyrosequencing and successfully cross-amplified 14 of these loci in A. manoel-felixii and a taxonomically uncertain taxon (a putative Ameroglossum hybrid). The number of alleles per loci ranged from 2 to 6, 2 to 5 and 2 to 6 in the examined populations of A. pernambucense, A. manoel-felixii and the putative hybrid, respectively. No significant linkage disequilibrium was detected, and significant deviation from Hardy–Weinberg equilibrium was found in some loci, likely reflecting inbreeding and population structure across inselbergs. We discuss the use of these SSR markers in conservation and microevolutionary studies in Ameroglossum, as well as in the investigation of the importance of pollen-mediated gene flow in keeping genetic diversity in rare species with patchily distributed populations using progeny arrays.

Floristic and ecological characterization of habitat types on an inselberg in Minas Gerais, southeastern Brazil

ABSTRACT Inselbergs are granitic or gneissic rock outcrops, distributed mainly in tropical and subtropical regions. They are considered terrestrial islands because of their strong spatial and ecological isolation, thus harboring a set of distinct plant communities that differ from the surrounding matrix. In Brazil, inselbergs scattered in the Atlantic Forest contain unusually high levels of plant species richness and endemism. This study aimed to inventory species of vascular plants and to describe the main habitat types found on an inselberg located in the state of Minas Gerais, in southeastern Brazil. A total of 89 species of vascular plants were recorded (belonging to 37 families), of which six were new to science. The richest family was Bromeliaceae (10 spp.), followed by Cyperaceae (seven spp.), Orchidaceae and Poaceae (six spp. each). Life forms were distributed in different proportions between habitats, which suggested distinct microenvironments on the inselberg. In general, habitats under similar environmental stress shared common species and life-form proportions. We argue that floristic inventories are still necessary for the development of conservation strategies and management of the unique vegetation on inselbergs in Brazil.

Floristic composition of a Neotropical inselberg from Espírito Santo state, Brazil: an important area for conservation

Our study on granitic and gneissic rock outcrops on Pedra dos Pontões in Espírito Santo state contributes to the knowledge of the vascular flora of inselbergs in southeastern Brazil. We registered 211 species distributed among 51 families and 130 genera. Orchidaceae, Bromeliaceae and Polypodiaceae were the most representative families. Concerning vegetative habit, herbs were predominant and about the preference for substrates, holorupicolous species and epiphytes were most speciose. The richest rocky habitat type was woody thicket, with 122 exclusive species. In total, 27 of the species registered in our study are cited on official lists of endangered plant species from Espírito Santo state and Brazil. In addition, two new records of angiosperms for Espírito Santo flora and two new species were recorded for the area. Our data demonstrates the importance of the area for conservation of unique biodiversity that serves as a sanctuary for a rich rupicolous flora composed of endemic and endangered species, some of which are new to science.

Rediscovery ofPilosocereus oligolepsis(Cactaceae) in the State of Roraima, Brazil

Pilosocereus oligolepis is a species of Cactaceae that is known only from three old type collections in Brazil (Roraima state) and Guyana. It is the only species of this genus to occur in northern Brazil. Due to the paucity of specimens and lack of precise locality data we undertook fieldwork in different vegetation types of Roraima aiming to find the species in the field. Populations of P. oligolepis were found in two previously unknown areas, occurring on granitic rock outcrops inside a vegetation mosaic of seasonal forests and savannas. Thus, it was possible to expand our knowledge of this species, increasing its occurrence and distributional data, as well as to provide pictures of the plants in their habitat and propose an updated conservation status.

Effects of removing exotic invasive species from the ecotones of two granite rock outcrops in the southeastern Piedmont of the United States

Piedmont granite rock outcrops in the southeastern United States support a plant community rich in endemic and rare plant species. The ecotones of the granite outcrop and Piedmont oak hickory forest communities are under increasing pressure from exotic invasion and the potential impacts of this invasion on the native plants in these communities are unclear. We conducted an experimental removal of invasive plant species at the ecotone of two granite rock outcrops and monitored species richness and plant occurrence along random belt transects in invaded, uninvaded, and removal plots for three years. These transects captured a representative sample of the plant community from the rock edge 20 m into the forest interior. Hemispherical photographs and soil samples were used to monitor changes in light availability and soil nutrients. Vegetation classes demonstrated spatial distribution patterns related to proximity to rock edge and depth of soil, but removal of invasive species had no apparent effect on percent cover or native plant richness. Sodium, calcium, and magnesium were all found to be significant predictors of invasive species occurrence and sodium and calcium were correlated with soil depth. This research effort suggests that the occurrence of invasive species are not significantly impacting overall species richness in the ecotone of outcrop plant communities, however changes to the species richness of this plant community in response to invasive species removal may take longer to detect.

Lichens of Granitic Rocks in Rocky Mountain National Park Larimer County, Colorado, U.S.A.

A survey of granitic rock surfaces, talus and outcrops, at 25 sites in Rocky Mountain National Park yielded 81 saxicolous lichen species. Fifteen species in 11 genera, or 19% of the total species, were dominant. Observed only once were 31% or 25 species. No new species were reported. Our results show typical saxicolous lichen communities with 57% crustose species.

Using Prescribed Burning to Restore Granite Rock Outcrop Ecotones in the Piedmont of the Southeastern United States

Rock outcrop habitats in the Georgia Piedmont of the United States host many endemic and rare plants, and the sensitivity of these endemic species to fire is unknown. After surveying 2 granite rock outcrops for 1 yr, we applied a winter burn treatment to their margins to observe the effect of burning on the plant community. Using measures of vegetation class occurrence and species richness, along with hemispherical photographs, soil nutrients, and soil depth, we monitored the success of the restoration effort. Burning did not significantly alter soil nutrients, pH, or the abundance of different vegetation classes. In the 2–yr period following the prescribed burn, burning did not significantly increase canopy openness or noticeably alter total species richness or woody species richness. The burn treatment did not significantly change invasive species richness or abundance, and abundance of the 2 rare rock outcrop endemics present, tenpetal thimbleweed ( Anemone berlandieri ) and granite stonecrop ( Sedum pusillum ), was not significantly impacted. Prescribed fire has been used as an effective tool for managing forests in the Piedmont by clearing fuel buildup on the ground and suppressing invading secondary hardwoods. The findings of our study suggest that prescribed winter burns can be an appropriate management tool for outcrop ecotones, but rock outcrop habitats are variable and the benefits of prescribed fire should be evaluated on a site-specific basis.

Alcantarea (Bromeliaceae) leaf anatomical characterization and its systematic implications

Alcantarea (Bromeliaceae) has 26 species that are endemic to eastern Brazil, occurring mainly on gneiss–granitic rock outcrops (‘inselbergs’). Alcantarea has great ornamental potential and several species are cultivated in gardens. Limited data is available in the literature regarding the leaf anatomical features of the genus, though it has been shown that it may provide valuable information for characterizing of Bromeliaceae taxa. In the present work, we employed leaf anatomy to better characterize the genus and understand its radiation into harsh environments, such as inselbergs. We also searched for characteristics potentially useful in phylogenetic analyses and in delimiting Alcantarea and Vriesea. The anatomical features of the leaves, observed for various Alcantarea species, are in accordance with the general pattern shown by other Bromeliaceae members. However, some features are notable for their importance for sustaining life on rock outcrops, such as: small epidermal thick-walled cells, uneven sinuous epidermal walls, hypodermis often differentiated into lignified layers with thick-walled cells, aquiferous hypodermis bearing collapsible cells, and the presence of well developed epicuticular stratum. Alcantarea leaves tend to show different shapes in the spongy parenchyma, and have chlorenchymatous palisade parenchyma arranged in more well-defined arches, when compared to Vriesea species from the same habitat.

Genetic structure of the xerophilous bromeliad Pitcairnia geyskesii on inselbergs in French Guiana – a test of the forest refuge hypothesis

Inselbergs are isolated granitic rock outcrops that provide distinctive ecological conditions. In northern South America they rise above the surrounding rainforest. Among inselberg specialists, Pitcairnia geyskesii (Bromeliaceae) is restricted to these habitats in French Guiana. We studied populations from 12 inselbergs using 7 microsatellite loci to give a “reverse image” of the reduction‐expansion of the rainforest in the context of the refuge hypothesis. Our analyses showed that populations are fragmented with dispersal occurring only over very short distances. Genetic diversity was higher in northern French Guiana, whereas specific alleles were observed in the south. The results point to the occurrence of a dry corridor in the north, as hypothesized by Tardy (1998) based on charcoal analyses, whereas de Granville's (1982) hypothesis of a unique past refuge is not confirmed. Moreover, our data suggests the importance of Oyapock River as a pathway for range expansion, arguing against the potential role of the Inini‐Camopi Mountains as a physical barrier. Finally, in spite of a strongly argued scenario in favour of a north‐to‐south migration history, a clear genetic isolation of P. geyskesii populations living on inselbergs of the Mitaraka archipelago suggests a distinct ancestry of the most southern populations.

Mate-guarding behavior in clam shrimp: a field approach

Precopulatory mate guarding is a complex behavior, influenced by many social and physiological factors, representing a case of intersexual conflict. Mate guarding has often been analyzed with the aid of theoretical models. In these models, it is commonly predicted that mate-guarding time is influenced by encounter rates between males and females, the contenders’ relative sizes, and the possible interaction among males (i.e., ‘‘takeovers’’: one guarding male displacing another). The factors influencing male and female guarding decisions have been measured in laboratory experiments but never under natural field conditions. In this field-based study, we observed mate-guarding couples of the clam shrimp Limnadia badia in ephemeral pools on granite rock outcrops in Western Australia. We recorded guarding duration, focusing on the factors considered important in mate-guarding models: male and female size, population density, sex ratio, operational sex ratio, and the status of female receptivity. We also estimated time budgets for males, the possibility of male takeovers, and the potential role of female resistance. We found that female receptivity stage (how close the female was to molting), small male size, and low absolute female presence are key factors in decreasing mate-guarding duration. This study adds a field dimension to manipulative laboratory projects and theoretical models of mate guarding. We were able to observe the simultaneous interactions of multiple factors in the field and to make a robust examination of the ideas of intersexual conflict during mate guarding in these crustaceans. Key words: branchiopoda, density,femaleresistance,fieldobservations,intersexualconflict,Limnadiabadia,malesize,sexratio,WesternAustralia. [BehavEcol]