Northern Source Research Articles

Detrital zircon geochronology of the Cretaceous Sindong Group, Southeast Korea: Implications for depositional age and Early Cretaceous igneous activity

AbstractThe Sindong Group forms the lowermost basin‐fill of the Gyeongsang Basin, the largest Cretaceous nonmarine basin located in southeastern Korea, and comprises the Nakdong, Hasandong, and Jinju Formations with decreasing age. The depositional age of the Sindong Group has not yet been determined well and the reported age ranges from the Valanginian to Albian. Detrital zircons from the Sindong Group have been subjected to U–Pb dating using laser ablation inductively coupled plasma mass spectrometry. The Sindong Group contains noticeable amounts of detrital magmatic zircons of Cretaceous age (138–106 Ma), indicative of continuous magmatic activity prior to and during deposition of the Sindong Group. The youngest detrital zircon age of three formations becomes progressively younger stratigraphically: 118 Ma for the Nakdong Formation, 109 Ma for the Hasandong Formation, and 106 Ma for the Jinju Formation. Accordingly, the depositional age of the Sindong Group ranges from the late Aptian to late Albian, which is much younger than previously thought. Lower Cretaceous magmatic activity, which supplied detrital zircons to the Sindong Group, changed its location spatially through time; it occurred in the middle and northern source areas during the early stage, and then switched to the middle to southern source areas during the middle to late stages. This study reports first the Lower Cretaceous magmatic activity from the East Asian continental margin, which results in a narrower magmatic gap (ca 20 m.y.) than previously known.

Provenance evolution of collapse graben fill in the Himalaya—The Miocene to Quaternary Thakkhola-Mustang Graben (Nepal)

This study focuses on the detailed provenance evolution of young, syn- to post-orogenic extensional grabens in orogens like the Himalaya to trace the tectonic history of such late-stage basins, using the Neogene Thakkhola-Mustang Graben as a case study. The graben is situated within the Tibetan-Tethys zone and is filled with > 870 m of continental deposits of Miocene to Holocene age-. Based on logged sections within the predominantly alluvial to coarse-grained fluvial fill of the graben we investigated paleocurrent data and the petrology of sandstones and conglomerates including heavy minerals studies to interpret provenance and source areas in detail. Significant changes are recorded by slight differences in heavy mineral and pebble compositions. The sandstones can be classified as lithic greywackes, lithic arkoses and feldspathic litharenites. Sandstone, mudstone, quartzite and some granite clasts are dominant in conglomerates of the central part of the graben. Tetang Formation conglomerates of Miocene age comprise mostly clasts of Mesozoic rocks with an eastern provenance, consistent with measured paleocurrent directions. All paleocurrent data and compositional analyses of imbricated conglomerates of the Miocene–Pliocene Thakkhola Formation in the northeast of the graben suggest that clasts were derived from eastern source areas comprising mainly Mesozoic rocks whereas Paleozoic clasts of a western to northern source area predominate in the centre of the graben. Heavy mineral analysis indicates that tourmaline, staurolite, zircon, garnet and apatite constitute a significant proportion of the assemblages of all formations through time whereas epidote, andalusite, kyanite, chloritoid, hornblende, chrome-spinel, rutile and amphiboles are less common. These assemblages reflect in general stable minerals and low to high-grade metamorphic source rocks, and are principally controlled by reworking of older, passive margin sediments of the Tibetan-Tethys zone as indicated by provenance discrimination diagrams. Three successive stages in provenance evolution were recognized: (1) The Miocene Tetang Formation, characterized by higher kyanite values, corresponding to the Himalayan foreland evolution; (2) the Thakkhola Formation, characterized by granite clasts and significantly higher amounts of andalusite, indicating source area expansion and erosion of the Mustang-Mugu granites to the northwest; (3) the Upper Pleistocene/Holocene Kaligandaki Formation, bearing higher amounts of epidote/klinozoisite and ophiolite and high-pressure/low temperature detritus as indicated by chrome spinel and blue amphiboles, derived from the north-lying Indus-Tsangpo suture zone. The change in source areas from the Miocene/Pliocene to the Late Pleistocene/Holocene is interpreted as a result of the evolution from an initial stage of high-angle normal faulting and collapse basin formation to a low-angle extensional detachment basin system.

Oil accumulation related to migration of source kitchens in the Lukeqin structural belt, Turpan-Hami Basin, China

The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.

What Sets the Strength of the Middepth Stratification and Overturning Circulation in Eddying Ocean Models?

Abstract The processes maintaining stratification in the oceanic middepth (between approximately 1000 and 3000 m) are explored using an eddy-resolving general circulation model composed of a two-hemisphere, semienclosed basin with a zonal reentrant channel in the southernmost eighth of the domain. The middepth region lies below the wind-driven main thermocline but above the diffusively driven abyssal ocean. Here, it is argued that middepth stratification is determined primarily in the model’s Antarctic Circumpolar Current. Competition between mean and eddy overturning in the channel leads to steeper isotherms and thus deeper stratification throughout the basin than would exist without the channel. Isotherms that outcrop only in the channel are nearly horizontal in the semienclosed portion of the domain, whereas isotherms that also outcrop in the Northern Hemisphere deviate from horizontal and are accompanied by geostrophically balanced meridional transport. A northern source of deep water (water with temperatures in the range of those in the channel) leads to the formation of a thick middepth thermostad. Changes in wind forcing over the channel influence the stratification throughout the domain. Since the middepth stratification is controlled by adiabatic dynamics in the channel, it becomes independent of the interior diffusivity κ as κ → 0. The meridional overturning circulation (MOC), as diagnosed by the mean meridional volume transport, also shows a tendency to become independent of κ as κ → 0, whereas the MOC diagnosed by water mass transport shows a continuing dependence on κ as κ → 0. A nonlocal scaling for MOC is developed that relates the strength of the northern MOC to the depth of isotherms in the southern channel. The results of this paper compare favorably to observations of large-scale neutral density in the World Ocean.

EXTREME ACTIVE MOLECULAR JETS IN L1448C

The protostellar jet driven by L1448C was observed in the SiO J=8-7 and CO J=3-2 lines and 350 GHz dust continuum at ~1" resolution with the Submillimeter Array (SMA). A narrow jet from the northern source L1448C(N) was observed in the SiO and the high-velocity CO. The jet consists of a chain of emission knots with an inter-knot spacing of ~2" (500 AU) and a semi-periodic velocity variation. The innermost pair of knots, which are significant in the SiO map but barely seen in the CO, are located at ~1" (250 AU) from the central source, L1448C(N). Since the dynamical time scale for the innermost pair is only ~10 yr, SiO may have been formed in the protostellar wind through the gas-phase reaction, or been formed on the dust grain and directly released into the gas phase by means of shocks. It is found that the jet is extremely active with a mechanical luminosity of ~7 L_sun, which is comparable to the bolometric luminosity of the central source (7.5 L_sun). The mass accretion rate onto the protostar derived from the mass-loss rate is ~10^{-5} M_sun/yr. Such a high mass accretion rate suggests that the mass and the age of the central star are 0.03-0.09 M_sun and (4-12)x10^3 yr, respectively, implying that the central star is in the very early stage of protostellar evolution. The low-velocity CO emission delineates two V-shaped shells with a common apex at L1448C(N). The kinematics of these shells are reproduced by the model of a wide opening angle wind. The co-existence of the highly-collimated jets and the wide-opening angle shells can be explained by the unified X-wind model" in which highly-collimated jet components correspond to the on-axis density enhancement of the wide-opening angle wind. The CO $J$=3--2 map also revealed the second outflow driven by the southern source L1448C(S) located at ~8.3" (2000 AU) from L1448C(N).

Spatial variability of sea level rise due to water impoundment behind dams

Dams have impounded ∼10,800 km3 of water since 1900, reducing global sea level by ∼30.0 mm and decreasing the rate of sea level rise. The load from impounded water depresses the earth's surface near dams and elevates the geoid, which locally increases relative sea level (RSL). We computed patterns of dam‐induced RSL change globally, and estimated that tide gauges, which are often close to dams, recorded only ∼60% of the global average sea level drop due to reservoir building. Thus, RSL in the globally averaged ocean rose ∼0.2 mm/yr more slowly than has been recorded by tide gauges, or ∼10% slower than the measured rise rate of 1.5–2.0 mm/yr. Relative proximity to dams caused RSL to rise fastest in northeastern North America and slowest in the Pacific. This dam‐induced spatial variability may mask the sea level “fingerprint” of melting sources, especially northern (Greenland) sources of glacial unloading.

Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35 ka BP)

The strength of the North Atlantic Meridional Overturning Circulation during climatically highly variable Marine Isotope Stage (MIS) 3 has attracted much attention in recent years. Here we present high-resolution Nd isotope compositions of past seawater derived from authigenic Fe–Mn oxyhydroxides recovered from drift sediments on the Blake Ridge in the deep western North Atlantic (ODP Leg 172, Site 1060, 3481 m water depth). The data cover the period from 45 to 35 ka BP, tracing circulation changes during major Heinrich iceberg discharge event 4 (H4, ∼40–39 ka BP). The Nd isotope record suggests that there was no northern-source water (NSW) mass like modern NADW at the deeper part of Blake Ridge at any time between 45 and 35 ka. This is fundamentally different from the hydrographic situation during the Holocene where NADW extends below 4500 m at this location. The ɛ Nd of past deep water recorded in the Blake Ridge sediments was least radiogenic during Dansgaard/Oeschger (D/O) Interstadial (IS) 8 ( ɛ Nd = −11.3) and most radiogenic immediately preceding IS 9 ( ɛ Nd = −9.8). More radiogenic compositions were also recorded during H4 (−10.2 ≤ ɛ Nd ≤ −9.9). The Nd isotope variability in MIS 3 matches that of a physical bottom current strength reconstruction from the same location. Neither record follows the pattern of Northern Hemisphere D/O climatic cycles. In our record, reduced mixing with northern source waters started in stadial 12 and lasted until after H4 in stadial 9, followed by a rapid increase in NSW contribution thereafter. This major change in the Nd isotope record predates the iceberg discharge event Heinrich 4 by more than 3 ka indicating a shallowing of the water mass boundary between Glacial North Atlantic Intermediate Water and Southern Source Water beneath. This early change in bottom water properties at the deep Blake Ridge suggests that North Atlantic deep water advection may already have decreased several thousand years before the actual iceberg discharge event and associated freshening of the surface waters in the North Atlantic. The change can thus not be attributed to climatic events in the North Atlantic but may be related to changes in flux of deep water from the South.

The geological position, sedimentary record and composition of the Tylicz Conglomerate (Late Eocene-Oligocene): stratigraphical and paleogeographical implications (Magura Nappe, Polish Outer Carpathians)

The geological position, sedimentary record and composition of the Tylicz Conglomerate (Late Eocene-Oligocene): stratigraphical and paleogeographical implications (Magura Nappe, Polish Outer Carpathians)During the Late Cretaceous to Paleogene the Magura Basin was supplied with clastic material from, non-existing today, source areas situated on the northern and southern margins of the basin. The northern source area is traditionally connected with Silesian Ridge, whereas the position of the southern one is still under discussion. The Upper Eocene-Oligocene pebbly mudstones of the Tylicz/Krynica facies zone contain exotic material derived from the south-Magura source area. The studied pebbles and clasts contain fragments of crystalline rocks, derived from a continental type of crust, and frequent clasts of Mesozoic to Paleogene deep and shallow-water limestones. Volcanites, rarely granitoides as well as schists, gneisses, quartzites and cataclasites were found in the group of crystalline exotic pebbles. The isotopic ages of "exotic" pebbles from the Tylicz section document a Variscan age of plutonic and metamorphic rocks. The composition of the Tylicz exotic conglomerates occupied the transitional position between the Jarmuta/Proč (Maastrichtian-Lower Eocene) and Strihovce (Eocene) exotic pebbles. The provenance of these rocks could be connected with Eocene exhumation of the SE sector of the Magura Basin basement. Another possibility can be explain by supply of siliciclastic material from a SE source area (Dacia and Tisza Mega-Units) and carbonate material from a S source area (ALCAPA Mega-Unit: Central Carpathian Block and Pieniny Klippen Belt).

Basin formation in the High Himalaya by arc-parallel extension and tectonic damming: Zhada basin, southwestern Tibet

[1] The late Miocene–Pleistocene Zhada basin in southwestern Tibet provides a record of subsidence and basin formation within an active collisional thrust belt. The >800 m thick basin fill is undeformed and was deposited along an angular unconformity on top of Tethyan strata that were previously shortened in the Himalayan fold-thrust belt. Modal sandstone petrographic data, conglomerate clast count data, and detrital zircon U-Pb age spectra indicate a transition from detritus dominated by a distal, northern source to a local, southern source. This transition was accompanied by a change in paleocurrent directions from uniformly northwestward to basin-centric. At the same time the depositional environment in the Zhada basin changed from a large, braided river to a closed-basin lake. Sedimentation in the Zhada basin was synchronous with displacement on the Qusum and Gurla Mandhata detachment faults, which root beneath the basin and exhume midcrustal rocks along the northwestern and southeastern flanks of the basin, respectively. These observations indicate that accommodation for Zhada basin fill was produced by a combination of tectonic subsidence and damming, as midcrustal rocks were evacuated from beneath the Zhada basin in response to arc-parallel slip on crustal-scale detachment faults.

Osvrt na staklene priloge iz starohrvatskog groblja na Ždrijacu u Ninu

U prilogu se na temelju novih spoznaja obrađuju stakleni nalazi (boca loptastoga tijela i dvije čaše na nozi) iz dostojanstveničkog, trojnog groba 322, te iz groba 310, sa starohrvatskog groblja na Ždrijacu u Ninu. Analizom dekorativnih elemenata, produkcijskih varijanti i kronoloških pokazatelja donesena je šira tipološka razrada, u kojoj se posebice ukazuje na tradicije kasnoantičkih, ranobizantskih radionica 6. i 7. stoljeća, koje su vidljive i na ninskim nalazima. Oživljavanje proizvodnje staklenih predmeta i posuđa, te kontinuiranje uzoraka u proizvodnji u staklarskim radionicama istočnog Sredozemlja, kao i u staklarskim radionicama sjeverne Italije, osobito onih koje možemo smatrati bizantskim filijalama, posebno je važna sastavnica u tumačenju staklenih priloga iz groba obitelji starohrvatskog odličnika. Jer i dospijeće tih predmeta u ninske grobove treba tražiti u trgovačkim, političko-diplomatskim, ili susretima na tragu kristijanizacije koje je ninski dostojanstvenik mogao ostvarivati sa Bizantskim ili Franačkim elitama.

Geomorphology of the Gubbio Basin (Central Italy): understanding the active tectonics and earthquake potential

The Gubbio Basin is a 22 km long, 4 km wide depression located within the North-Central Apennines fold-andthrust belt. The basin is bounded to the east by the Gubbio Fault, a W-dipping, normal fault dissecting a large Jurassic-Oligocene anticline. Although located along one of the main seismogenic zones of the Peninsula, both historical and instrumental is seismicity is limited with the only exception for the 29 April 1984, Ms 5.3 earthquake, which occurred about 10 km southwest of the basin. Most of the literature attributes this seismicity to the Gubbio Fault. New geomorphic and geologic investigations based on field and aerial photo surveys and DEM analyses provide new insights on the active faulting in the area and are used to infer potential seismogenic sources. Limited evidence of ongoing deformation along the surface expression of the Gubbio Fault was found, possibly because of low rates of deformation versus fast erosional processes. The western side of the basin appears to be controlled by an east-dipping normal fault, antithetic to the Gubbio Fault. Standard dislocation modeling was used to understand the role played by the Gubbio Fault and its antithetic. The Gubbio Fault was divided into a high-angle section above 3.5 km and a low-angle section between 3.5 and 6 km depth. Based on different tests we conclude that both sections of the Gubbio Fault as well as the antitethic fault contributed to the present setting of the basin. At present the antithetic fault appears to be the most effective in producing a geomorphic signature and controlling the basin width. The high-angle Gubbio Fault played a major role in the basin growth but now its activity rate appears minor. Because of the characteristics and location of the 1984 earthquake, the low-angle Gubbio Fault is assumed to be presently active and seismogenic. Based on the integration of geologic, geomorphic and seismological data we suggest that the low-angle Gubbio Fault is formed by two individual sources capable of M 5.3-5.9 earthquakes. The southern source ruptured in the 1984 earthquake while the northern source did not rupture recently nor historically.

Redox trapping of arsenic during groundwater discharge in sediments from the Meghna riverbank in Bangladesh.

Groundwater arsenic (As) is elevated in the shallow Holocene aquifers of Bangladesh. In the dry season, the shallow groundwater discharges to major rivers. This process may influence the chemistry of the river and the hyporheic zone sediment. To assess the fate of As during discharge, surface (0-5 cm) and subsurface (1-3 m) sediment samples were collected at 9 sites from the bank of the Meghna River along a transect from its northern source (25 degrees N) to the Bay of Bengal (22.5 degrees N). Bulk As concentrations of surface sediment averaged 16 +/- 7 mg/kg (n = 9). Subsurface sediment contained higher mean concentrations of As of 4,000 mg/kg (n = 14), ranging from 1 to 23,000 mg/kg As, with >100 mg/kg As measured at 8 sites. X-ray absorption near-edge structure spectroscopy indicated that As was mainly arsenate and arsenite, not As-bearing sulfides. We hypothesize that the elevated sediment As concentrations form as As-rich groundwater discharges to the river, and enters a more oxidizing environment. A significant portion of dissolved As sorbs to iron-bearing minerals, which form a natural reactive barrier. Recycling of this sediment-bound As to the Ganges-Brahmaputra-Meghna Delta aquifer provides a potential source of As to further contaminate groundwater. Furthermore, chemical fluxes from groundwater discharge from the Ganges-Brahmaputra-Meghna Delta may be less than previous estimates because this barrier can immobilize many elements.

Regional genetic variation in three native grasses in northern California

Germination, growth, and flowering traits varied widely in a common-garden nursery environment and expressed coarse-textured geographic patterns among Plumas National Forest seed sources of 3 native grasses (Poaceae): blue wildrye ( Elymus glaucus Buckley ssp. glaucus , California brome ( Bromus carinatus Hook. & Arn. var. carinatus ), and Orcutt's brome ( B. orcuttianus Vasey). Seed zones are justified to partition the geographic variation in grasses on the Plumas National Forest because: 1) adaptive traits varied significantly with geographic surrogates for climate and photoperiod; 2) a coarse-textured geographic and topographic pattern overshadowed microsite variation; and 3) paired (proximal) sources were more similar to one another than more distal sources, all of which indicated selection may have contributed to population differentiation. Each species displayed a different geographic pattern, but Bromus species were most similar. Low-elevation southwestern sources of B. carinatus had earlier and higher germination and slightly higher shoot dry weight, while high-elevation northern lots had later and lower germination and dry weight. S outhern sources of B. orcuttianus produced more flowers and germinated earlier than northern sources. Elymus glaucus from lower-elevation and more eastern sources, where summer drought is most pronounced, had higher dry weight and flowers. Kitzmiller JH. 2009. Regional genetic variation in three native grasses in northern California. Native Plants Journal 10(3):263–280. Kitzmiller JH. 2009. Regional genetic variation in three native grasses in northern California. Native Plants Journal 10(3):263–280.

Geographically congruent large-scale patterns of plastid haplotype variation in the European herbs Silene dioica and S. latifolia (Caryophyllaceae)

The closely related dioecious herbs Silene latifolia and Silene dioica are widespread and predominantly sympatric in Europe. The species are interfertile, but morphologically and ecologically distinct. A study of large-scale patterns of plastid DNA (polymerase chain reaction-restriction fragment length polymorphism) haplotypes in a sample of 198 populations from most of the European ranges of both species revealed extensive interspecific haplotype sharing. Four of the 28 detected haplotypes were frequent (found in > 40 populations) and widespread. Three of these frequent haplotypes occurred in both species and the geographic distribution of each haplotype was broadly congruent in both species. Each of these three, shared and widespread haplotypes is likely to have colonized central and/or northern Europe after the last glaciation from one or more of refugial areas in southern Europe. Interspecific hybridization and plastid introgression within refugial regions and/or during the early stages of postglacial expansion is the most plausible explanation for the broadly similar distribution patterns of the shared, frequent chloroplast haplotypes in the two species. The fourth frequent, widespread haplotype was absent from S. latifolia and almost entirely restricted to Nordic S. dioica. It is most likely that this haplotype spread into the Nordic countries from a central or northern European source or from a refugial area in Russia. (c) 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161, 153-170.

Oshá (bear root)Ligusticum porteriJ.M. Coult. & Rose var.porteri

Osha roots ( Ligusticum porteri J.M. Coult. & Rose var. porteri [Apiaceae]) are prized by Native Americans as a medicinal for respiratory illnesses; roots from wild stands are most commonly used. Native to the western and southwestern US, osha is a slow-growing plant that takes up to 10 y to reach harvestable mass in the wild. Demand for L. porteri has been increasing and over-harvest threatens native stands. Attempts to propagate osha for replenishing native stands and for developing alternatives to wild harvest have been inconsistent and variable by seed source. Simple seed stratification methods were tested to propagate plants for sustainable production of osha. Seed germination of 3 commercial seed sources (New Mexico, Utah, and Colorado) improved when the stratification period was adjusted for origin of seeds. An increased duration of stratification (10 wk) was required for the more northern sources. These results indicate that common seed stratification can be used to develop nursery plants for re-establishment and production of harvestable roots.

Crockerland - The Source Area for the Triassic to Middle Jurassic Strata of Northern Axel Heiberg Island, Canadian Arctic Islands

Abstract The main source terrains for the Sverdrup Basin of Arctic Canada lay to the south and east and comprised the extensive Canadian and Greenland cratons which were mainly covered by Devonian siliciclastic strata. From Carboniferous to mid-Jurassic, the basin also received sediment from a northern source area, named Crockerland. The Triassic-Jurassic succession of northernmost Axel Heiberg Island was examined to document the facies and stratigraphic distribution of Crockerland-derived sandstones in the succession. Such sandstones were identified by documenting a southward facies change to offshore siltstone and shale. Northerly-derived sandstones were found to be common in the Lower Triassic, Upper Triassic and lower Middle Jurassic portions of the succession. Their presence in the sandstone-dominant, uppermost Triassic–Lower Jurassic succession was not determined due to difficulties in differentiating northerly-derived sediments from those derived from the south and east. All three Lower Triassic sequences contain sandstones of shallow to offshore shelf origin. Sandstone units are up to 45 m thick and the sandstone facies tract for each sequence is estimated to have been about 100 km wide. Thick intervals of beach to offshore shelf sandstones occur in two Carnian (Upper Triassic) sequences and the sandstones of the upper sequence are truncated northward by a major unconformity. This indicates that in late Carnian the Crockerland shoreline was well south of the northern tip of Axel Heiberg Island. Northerly-derived, Middle Jurassic (Aalenian) sandstones are preserved at only two localities. They are extensively burrowed and are of middle to outer shelf origin. On the basis of the amount, composition and grain size of the sediment derived from Crockerland, it appears that low-lying, sedimentary strata characterized this source terrain. If Triassic to mid-Jurassic strata are preserved below the Cretaceous-Tertiary continental terrace wedge on the inner portion of the continental shelf north and west of Axel Heiberg, the succession may contain shallow shelf to beach sandstones which have the potential to act as reservoirs for petroleum.

Goniopolarimetric study of the revolution 29 perikrone using the Cassini Radio and Plasma Wave Science instrument high‐frequency radio receiver

We present goniopolarimetric (also known as direction finding) results of the Saturn kilometric radiation (SKR), using the Cassini Radio and Plasma Wave Science instrument high‐frequency radio receiver data. Tools to retrieve the characteristics of the SKR sources have been developed that allow us to measure their 3‐D location and beaming angle relative to the magnetic field in the source and, thus, to deduce the location of the footprints of the active magnetic field lines. We present results from these analyses on SKR observed during the revolution 29 perikrone (25–26 September 2006) with a relatively high orbital inclination. These results provide for the first time the observed beaming angle, the invariant latitude, and the local time of the SKR sources. We provide evidence that the SKR is mainly emitted in the right‐hand extraordinary (R‐X) mode and marginally in the left‐hand ordinary (L‐O) mode. We observe the footprint of the active magnetic field lines in the ∼70° to ∼80° northern and southern latitudinal range and in the 0400 to 1600 local time range. The northern sources are observed at slightly higher latitude than southern sources. The location matches that of the UV and IR aurorae. Duskside and nightside sources are also detected.

Reconstruction of currents in the Mid-Ordovician–Early Silurian central Baltic Basin using geochemical and mineralogical indicators

In the central part of the Mid-Ordovician–Early Silurian Baltic Basin, two different transport pathways of terrigenous material can be recognized. Kaolinite indicates the south-to-north sediment influx, and Cr the western and northern sources. A pathway from the Ukrainian Shield in the South was active in the Floian–Darriwilian (Ordovician) and in the Llandovery (Silurian). The influx from the western source was active in the Sandbyan, and influx from the northern side occurred in the Katyan. The sediment transport was carried out by water flows, which turned into rapid currents from time to time. These currents, coming from the ocean surface waters, were oxygenated facilitating red facies formation in the central Baltic Basin. Currents on the shelf were linked to the adjacent oceanic currents, which changed in course with the drift of Baltica from temperate to subtropical latitudes.

Boreal forest provenance tests used to predict optimal growth and response to climate change: 2. Black spruce

Height, diameter, and survival data were obtained from 20 range-wide black spruce ( Picea mariana (Mill.) BSP) provenance trials established from 1973 to 1977. Population response functions based on February minimum temperatures were developed for 23 Ontario and Great Lakes states provenances to predict climate values maximizing height growth for individual seed sources. Site transfer functions based on February maximum temperatures and May maximum temperatures were developed for five test sites to predict climate values maximizing height growth for test locations. Contour lines representing optimal performance were fitted to current (1961–1990) and future (2041–2070) climate grids. For black spruce seed sources from the east of Lake Superior and Lake Huron, optimal height growth was achieved between 45° and 47°N; for the western sources optimal performance moved north between 46° and 48°N. In eastern Ontario, height growth of northern sources may increase with transfer to warmer environments and with future temperature increases. Central sources are currently growing at or close to optimum and will be negatively affected by increased future temperatures. Southern sources may currently benefit from transfer to cooler environments, and the effects of global warming may cause significant height growth loss and the potential extirpation of local populations.

On the relationship between BL Lacertae objects and radio galaxies

We present deep radio images at 1.4 GHz of a large and complete sample of BL Lacertae objects (BL Lacs) selected from the Deep X-ray Radio Blazar Survey (DXRBS). We have observed 24 northern sources with the Very Large Array (VLA) in both its A and C configurations and 15 southern sources with the Australia Telescope Compact Array (ATCA) in its largest configuration. We find that in the DXRBS, as in the 1-Jy survey, which has a radio flux limit roughly ten times higher than the DXRBS, a considerable number (about a third) of BL Lacs can be identified with the relativistically beamed counterparts of Fanaroff-Riley type II (FR II) radio galaxies. We attribute the existence of FR II-BL Lacs, which is not accounted for by current unified schemes, to an inconsistency in our classification scheme for radio-loud active galactic nuclei (AGN). Taking the extended radio power as a suitable measure of intrinsic jet power, we find similar average values for low- (LBL) and high-energy peaked BL Lacs (HBL), contrary to the predictions of the blazar sequence.