An intercomparison of single and dual-source vegetation-atmosphere transfer models applied to transpiration from sahelian savannah

Three models of the partitioning of net radiation into latent and sensible heat fluxes over Sahelian savannah are described. Each model has a different configuration of stomatal and aerodynamic resistances. Their performance was assessed by comparison against field measurements of latent heat flux over savannah vegetation consisting of bushes interspersed with a herbaceous understorey. The modelled results indicate that in dry conditions, a Penman-Monteith based single source model performs adequately when predicting the latent heat flux. However, the models with two sources demonstrate that the bushes and herbs have very different responses to local climate. In all the models, evaporation is highly sensitive to stomatal resistance, suggesting that a better understanding of stomatal response would improve the accuracy of the models.     

Petrogenesis and syntectonic emplacement in the early Proterozoic of south-central Finland: a reversely zoned diorite-granodiorite and a granite

The Hernemäki and Sydänmaa granitoid plutons in southern Finland lie within the Svecokarelian metagreywackes, with an approximate age of 1.9 Ga. The Hernemäki porphyritic granite was emplaced and deformed early in the regional D₂ deformation, and acquired a rectilinear foliation. The Sydänmaa pluton has a mainly concentric foliation, and its intrusion spanned D₂. It was probably emplaced as a ballooning pluton. The magmas of the two plutons were possibly derived from a similar source, but evolved independently. Both plutons show plagioclasebiotite-hornblende fractionation. The Sydänmaa pluton is reversely zoned, with a granodiorite rim and a diorite core.Crystal-residual liquid segregation in a deep magma chamber produced a normal geochemical stratification. This fractionated magma was drained from the top down, and injected into a higher, final chamber. Hence, the granodiorite was emplaced before the diorite. There is a component of normal zonation, which suggests that early hornblende crystals were incorporated in the most fractionated granodiorite.

---

Zusammenfassung Die Hernemäki- und Sydänmaa-Granite in Südfinnland liegen innerhalb der svecokarelischen Metagrauwacken und haben ein ungefähres Alter von 1,9 Ga. Der porphyrische Hernemäki-Granit intrudierte frühzeitig während der regionalen D, Deformation. Er wurde zur gleichen Zeit deformiert, woraus eine geradlinige Schieferung resultierte. Der Sydänmaa-Granit, dessen Intrusoin die D,-Phase überdauerte, zeigt dagegen eine überwiegend konzentrische Schieferung. Sehr wahrscheinlich stieg er als ballonförmiger Granit auf.Die Magmen der zwei Plutone entstammen eventuell derselben Quelle, entwickelten sich aber unabhängig voneinander. Beide zeigen Plagioklas-Biotit-Hornblende Fraktionierung. Der Sydänmaa-Granit ist umgekehrt zoniert, er hat einen Granodiorit-Rand und einen Diorit-Kern. Residuale Flüssigkeitsdifferenzierung in einer tiefgelegenen Magmenkammer erzeugte eine normale geochemische Abfolge. Dieses fraktionierte Magma floß vom Top des Plutons nach unten ab und wurde in eine höher gelegene Kammer injiziert. Also intrudierte der Granodiorit vor dem Diorit. Es existiert eine Komponente normaler Zonierung, was für eine Aufnahme früh gebildeter Hornblendekristalle in den am stärksten fraktionierten Granodiorit spricht.

---

Résumé Les plutons granitoïdes de Hernemäki et Sydänmaa (Finlande méridionale) sont inclus dans les métagrauwackes svecocaréliennes, avec un âge approximatif de 1,9 Ga. Lors du début de la déformation régionale D₂, le granite prophyrique de Hernemäki s'est mis en place et a été déformé, acquérant ainsi une structure linéaire. Le pluton de Sydänmaa, dont l'intrusion a dépassé la phase D₂, possède une schistosité essentiellement concentrique. Il a été probablement mis en place par »ballooning«. Il est possible que les magmas des deux plutons dérivent d'une source similaire, mais ils ont évolué de manière indépendante. Les deux plutons montrent un fractionnement par cristallisation du plagioclase, de la biotite et de la hornblende. Celui de Sydänmaa présente une zonation inverse: bordure granodioritique et coeur dioritique. La séparation des cristaux et du liquide résiduel dans une chambre magmatique profonde a engendré une stratification géochimique normale. La partie supérieure de cet ensemble fractionné a ensuite été injectée dans une chambre définitive plus élevée, suivie des parties plus profondes: de la sorte, la granodiorite s'est mise en place avant la diorite. Il existe une composante de zonation normale, qui laisse supposer que de la hornblende, cristallisée lors des premiers stades, a été incorporée à la fraction granodioritique ultime.

---

Hernemki Sydnmaa ; 1,9 Ga. Hernemaki , D₂, , . Sydnmaa, D₂, . . - , , . - . Sydnmaa , , - . . . , , — . , .

     

A comparison of lead-isotope measurements on exploration-type samples using inductively coupled plasma and thermal ionization mass spectrometry

Thermal ionization mass spectrometry (TI-MS) has long been the method of choice for Pb-isotope determinations. More recently, however, inductively coupled plasma mass spectrometry (ICP-MS) has been used to determine Pb-isotope ratios for mineral exploration. The ICP-MS technique, although not as precise as TI-MS, may promote a wider application of Ph-isotope ratio methods because it allows individual isotopes to be determined more rapidly, generally without need for chemical separation (e.g., Smith et al., 1984; Hinners et al., 1987). To demonstrate the utility of the ICP-MS method, we have conducted a series of Pb-isotope measurements on several suites of samples using both TI-MS and ICP-MS.     

Diatom assemblages from Adirondack lakes (New York,USA) and the development of inference models for retrospective environmental assessment

Detrended canonical coreespondence analysis (DCCA) was used to examine the relationships between diatom species distributions and environmental variables from 62 drainage lakes in the Adirondack region, New York (USA). The contribution of lakewater pH, Al_m (monomeric Al), NH₄, maximum depth, Mg, and DOC (dissolved organic carbon) were statistically significant in explaining the patterns of variation in the diatom species composition. Twenty-three and sixteen diatom taxa were identified as potential indicator species for pH and Al_m, respectively (i.e. a taxon with a strong statistical relationship to the environmental variable of interest, a well defined optimum, and a narrow tolerance to the variable of interest). Using weighted-averaging regression and calibration, predictive models were developed to infer lakewater pH (r ²=0.91), Al_m (r ²=0.83), DOC (dissolved organic carbon) (r ²=0.64), and ANC (acid neutralizing capacity; r ²=0.90). These variables are of key importance in understanding watershed acidification processes. These predictive models have been used in the PIRLA-II (Paleoecological Investigation of Recent Lake Acidification-II) project to answer policy-related questions concerning acidification, recovery, and fisheries loss.     

Interactions among some dominant estuarine nekton species

Interactions between pairs of numerically dominant species collected at inlet and creek shorezone and channel habitats within a high salinity estuary in northeastern South Carolina were examined using two-way contingency tables and binomial tests. Of the significant species interactions, over 71% were positive and these primarily occurred within shorezone habitats. The strongest positive interactions were between young-of-the-year spot (Leiostomus xanthurus) and blue crab (Callinectes sapidus) juveniles in both shorezone habitats, and between striped killifish (Fundulus majalis), white mullet (Mugil curema), and striped anchovies (Anchoa hepsetus) in the inlet shorezone habitat. One of the most positive species associations in channel habitats was between the bay anchovy (Anchoa mitchilli) and the Atlantic brief squid (Lolliguncula brevis). These positive relationships between species may be explained by one species enhancing the habitat for another, both species responding to similar environmental conditions, cooperative social interactions such as mixed schooling, or the attraction of predators to prey. Negative interactions were found between schools of Atlantic silversides (Menidia menidia) and striped killifish in the inlet shorezone and between schools of Atlantic silversides and bay anchovies in the creek shorezone. Schools of Atlantic silversides may either displace or compete with other common shorezone species. Positive and negative interactions suggest that relationships between some species pairs did not occur randomly within certain habitats and may have contributed to the organization of the estuarine nekton community. Differences in the strengths and direction of interactions of certain species pairs among habitats and seasons were probably related to the differences in the physical characteristics of those habitats and/or changes in the relative abundance of dominant species and life stages over time.     

Cenozoic tectonics in the Urumgi-Korla region of the Chinese Tien Shan

Cenozoic deformation within the Tien Shan of central Asia has accommodated part of the post-collisional indentation of the Indian plate into Asia. Within the Urumgi—Korla region of the Chinese Tien Shan this occurred dominantly on thrusts, with secondary strike-slip faulting. The gross pattern of deformation is of moderate to steeply dipping thrusts that have overthrust foreland basins to the north and south of the range, the Junggar and Tarim basins, respectively. Smaller foreland basins lie within the margins of the range itself (Turfan, Chai Wo Pu, Korla and Qumishi basins); these lie in the footwalls of local thrust systems. Both the Turfan and the Korla basins contain major thrusts within them; they are complex foreland basins. Deformation has progressively affected regions further into the interior of the Junggar Basin, and propagated into the interiors of the intermontane basins. No unidirectional deformation front has passed across the Tien Shan in the Neogene and Quaternary. An Oligocene unconformity may indicate the time of the onset of the Cenozoic deformation, but most of the Cenozoic molasse has been deposited after the Palaeogene. The rate of deposition in basins next to the uplifted ranges has increased since the onset of deformation. There has been at least about 80 km of Cenozoic shortening across this part of the Tien Shan. Cenozoic shortening is greater in sections of the range further west; these are nearer to the northern margin of the Indian indenter. Cenozoic compression has reactivated structures created by the two late Palaeozoic collisions that created the ancestral Tien Shan. These Palaeozoic structures have exerted a strong control over the style and location of the Cenozoic deformation.     

Metal speciation (Cu, Zn, Pb) and organic matter in an oxic salt marsh, Severn Estuary, southwest Britain

Predominantly anthropogenic Cu, Zn, and Pb present in an approximately 100 yr old mud flat and salt marsh deposit at a high intertidal, oxic site are bound chiefly in the Fe---Mn oxide-hydroxide, organic and residual phases. The amount of each metal in the organic phase is significant and declines with increase in the age of the buried sediment, in harmony with the total amount of organic matter remaining. Application of a quantitative geochemical model provides evidence that those metals remobilized by the progressive oxic degradation of the organic matter do not swell the oxide phase also present in the deposit, but are free to be flushed back into the estuary.     

Mineral resources of China: Apparent controls on distribution

This paper attempts to define apparent mineral distribution patterns of China according to tectono-stratigraphic terrane geology. Associations between specific mineral and hydrocarbon deposits and specific tectono-stratigraphic terranes in China suggest that deposits of certain types are spatially constrained by terrane geology. The definition of specific tectono-stratigraphic terranes of China is a valuable initial step in interpreting the geologic history of the nation, although terrane analysis of China is at a very early stage. The recognition that specific deposit types are associated with specific tectono-stratigraphic terranes may make it possible to select appropriate analogues from elsewhere in the world to evaluate China's mineral and hydrocarbon potential. Additionally, understanding the associations between mineral and hydrocarbon deposits and tectono-stratigraphic terranes in China may serve as an aid to future exploration in the nation.     

Supergranular line profile variation of Mg i λ2852

The chromospheric network is barely visible in the Mg i 2852 line. Unlike in plages, where it shows well-defined self-reversed emission structure in the core, the line is an unreversed absorption feature in the network boundaries, exhibiting only a small blue asymmetry. In the network cell interiors, the line is unreversed and symmetrical.