Evaluating the Levels and Human Health Risks of Heavy Metals in Soils around Onne Landfill, Rivers State, Nigeria

This study evaluated selected heavy metals’ levels in soil around the landfill in Onne Rivers State, Nigeria. It also examines potential human health risks due to exposure to the contaminated soil. Composite samples of soils from the northern, southern, eastern and western domains of the landfill were collected, processed, and analysed for heavy metals using atomic absorption spectrophotometry, and their human health risks were evaluated. The heavy metals’ levels in the soils around the four domains were in the order Pb>Cr>Ni>Cd>As. Children and adult ingestion, inhalation and dermal hazards quotients for the selected metals in the four domains were below unity ranging from {(HQchildren 2.71 x 10-10 As inhalation in the eastern domain to 9.24 x 10-1 Pb ingestion in the northern domain); HQadult 1.55 x 10-10 As inhalation in the eastern domain to 9.90 x 10-2 Pb ingestion in the northern domain)}. Adult ingestion, inhalation and dermal cancer risks (CRadult) were within acceptable limits, ranging from 1.99 x 10-13 As inhalation in the eastern domain to 4.68 x10-5 Cr ingestion in the northern domain. However, ingestion cancer risk for children (CRchildren) due to exposure to Ni and Cr in the four domains were above tolerable limit ranging from {(Ni - 2.00 x 10-4 in the southern domain to 3.11 x 10-4 in the northern domain); Cr – 2.95 x 10-4 in the southern domain to 4.37 x 10-4 in the northern domain)}. Children and adult hazards index due to exposure to the selected metals were also less than 1.0, ranging from children exposure to Ni (5.91 x 10-3) in the southern domain and Pb (9.25 x 10-1) in the northern domain to adult exposure to Ni (6.50 x 10-4 in the southern domain and Pb (9.94 x 10-2) in the northern domain. Total cancer risks (TCRadult) due to adult exposure to the metals were within tolerable limit, ranging from Cd (4.93 x 10-7) in the southern domain to Cr (5.01 x 10-5) in the northern domain. And total cancer risk (TCRchildren) due to children exposure to Ni and Cr were above tolerable limit, ranging from {Ni (2.40 x 10-4 in the southern domain to 3.74 x 10-4 in the northern domain); Cr (3.54 x 10-4 in the southern domain to 5.24 x 10-4 in the northern domain)}. The values for both non carcinogenic and carcinogenic risks were higher for children than those for adult. Reasons for this attributes and improvement actions were suggested.

Tectonic domains and exhumation history of the Omineca Belt in southeastern British Columbia from 40Ar/39Ar thermochronology

A large geochronological data set comprising 40Ar/39Ar and K–Ar (hornblende, muscovite, biotite, and K-feldspar), Rb–Sr (muscovite), fission track (zircon and apatite) and U–Pb (zircon and monazite) dates has been compiled for the southern Kootenay Arc and western Purcell anticlinorium in the Omineca Belt of the Canadian Cordillera in southeastern British Columbia. New 40Ar/39Ar data for hornblende, muscovite, biotite, and alkali feldspar are presented and combined with data from other studies. We integrate these data with recent advances in the geology of the region to define three partially fault-bounded domains with differing geological and exhumation histories, here termed the western, central, and eastern domains. The western domain is characterized by (1) late synkinematic Jurassic plutons with hornblende, muscovite, and biotite 40Ar/39Ar plateau dates between 170 and 165 Ma, some of which are within error of the U–Pb zircon dates for these plutons, and (2) late Early Cretaceous (118–102 Ma) plutons commonly with concordant mica 40Ar/39Ar plateau dates of a similar age range, indicating rapid cooling following emplacement of both suites. The central domain is bounded by regional-scale normal faults (Gallagher and Midge Creek faults, Blazed Creek/Next Creek faults, and Purcell Trench fault) and contains superposed Early and Late Cretaceous zones of Barrovian metamorphic rocks and several mid- to Late Cretaceous, post-kinematic plutons. The transition from the western domain into the central domain is characterized by 40Ar/39Ar mica age spectra showing a progression of increasing thermal overprinting. Along the north–south length of the central domain, biotite and muscovite yield Paleocene to Eocene K–Ar and 40Ar/39Ar plateau dates between 66 and 40 Ma. The eastern domain consists of (1) a southern portion that occurs in the hanging wall of the Purcell Trench fault, comprising mid-Cretaceous intrusions of the Bayonne magmatic suite emplaced into biotite zone metasedimentary rocks of the Mesoproterozoic Belt-Purcell Supergroup in the western Purcell anticlinorium, and (2) a northern portion that shows a continuous transition with the northern part of the central domain north of the terminus of the Purcell Trench fault. Cretaceous igneous rocks in the southern portion of the eastern and western domains have 40Ar/39Ar mica plateau dates that are <9 Myr younger than U–Pb zircon dates, indicating rapid cooling shortly after emplacement. 40Ar/39Ar step-heating reveals that there was a mid- to Late Cretaceous thermal disturbance in the eastern domain, possibly related to emplacement of younger plutons at deeper crustal levels and the Late Cretaceous Barrovian metamorphic event recorded in rocks of the central domain, such that biotite with dates <ca. 73 Ma yield plateau age spectra but those with older dates are disturbed. The new geochronology, combined with recent mapping and metamorphic studies, leads to the conclusion that the exhumation of the Barrovian metamorphic rocks of the central domain was a multi-stage process. The central domain experienced rapid tectonic decompression and minor pluton emplacement in the Late Cretaceous to early Paleocene (76–61 Ma) when the Cordilleran orogen was under regional contraction during which most of the exhumation occurred. Final exhumation in the footwall of Eocene normal faults was less significant and occurred between 53 and ca. 46 Ma when the Cordilleran orogen had transitioned to regional extension, by which time the three domains had attained a similar crustal level. These episodes of exhumation are similar to those found in other core complexes in the southern Canadian Cordillera and contiguous northern Idaho and Washington. The earlier episode is coincident with regional-scale, Late Cretaceous thrust faulting in the Foreland Belt of the Rocky Mountains. Eocene normal faulting and final exhumation of core complexes in the Omineca Belt mark the end of contraction in the Foreland Belt.

U-Pb age and metamorphism of rocks of Voshnevogorsky sequence (South Ural)

In the article present results of U-Pb — dating of zircons and petrologic-geochemical study of garnet-biotite plagiogneises and quartz-plagioclase-amphibole granofels host rocks samples from Vishnevogorsky sequence of the oldest rocks of the southern Urals Eastern domain are presented. U-Pb-dating of zircons were obtained by ion microprobe (SHRIMP II). The maximum age of the substrate plagiogneises Vishnevogorsky sequence not younger than 2700 Ma, and granulitic metamorphism plagiogneises falls on the Proterozoic age range 1740–2220 Ma. The dates obtained for plagiogneises and granofels Vishnevogorsky sequence reflect all major (PR1–P1) age stages of the Urals development. Many of the dated events are manifested only in the zircons generation and are not reflected in the mineral paragenesises of the studied rocks.

Reconciling zircon and monazite thermometry constrains H2O content in granitic melts

&lt;p&gt;In this contribution, we compare and test the reliability of zircon and monazite thermometers and suggest a new and independent method to constrain the H&lt;sub&gt;2&lt;/sub&gt;O content in granitic magmas from coeval zircon and monazite minerals. We combine multi-method single-mineral thermometry (bulk-rock zirconium saturation temperature (T&lt;sub&gt;zr&lt;/sub&gt;), Ti-in-zircon (T&lt;sub&gt;(Ti-zr&lt;/sub&gt;&lt;sub&gt;)&lt;/sub&gt;) and monazite saturation temperature (T&lt;sub&gt;mz&lt;/sub&gt;)) with thermodynamic modelling to estimate water content and P&amp;#8211;T conditions for strongly-peraluminous (S-type) granitoids in the Georgetown Inlier, NE Queensland. These granites were generated within ~30 km thick Proterozoic crust, and emplaced during regional extension associated with low-pressure high-temperature (LP&amp;#8211;HT) metamorphism.&lt;/p&gt;&lt;p&gt;SHRIMP U&amp;#8211;Pb monazite and zircon geochronology indicates synchronous crystallization ages of c. 1550 Ma for granitic rocks emplaced at different crustal levels&amp;#8212;from the eastern deep crustal domain (P = 6&amp;#8211;9 kbar), through the middle crustal domain (P = 4&amp;#8211;6 kbar), to the western upper crustal domain (P = 0&amp;#8211;3 kbar).&lt;/p&gt;&lt;p&gt;Bulk-rock T&lt;sub&gt;zr&lt;/sub&gt; and T&lt;sub&gt;(Ti-zr&lt;/sub&gt;&lt;sub&gt;)&lt;/sub&gt; yielded magma temperature estimates for the eastern domain of ~800&amp;#176;C and ~910&amp;#8211;720&amp;#176;C, respectively. Magma temperatures in the central and western domains were ~730&amp;#176;C (T&lt;sub&gt;zr&lt;/sub&gt;) and ~870&amp;#8211;750&amp;#176;C (T&lt;sub&gt;(Ti-zr)&lt;/sub&gt;) in the central domain, and ~810&amp;#176;C (T&lt;sub&gt;zr&lt;/sub&gt;) and ~890&amp;#8211;720&amp;#176;C (T&lt;sub&gt;(Ti-zr)&lt;/sub&gt;) in the western domain, respectively. These temperature estimates were compared with P&amp;#8211;T conditions recorded in the host rocks to determine if the magmas had equilibrated thermally with the crust. Similar temperatures were obtained for the middle and lower crust suggesting that the associated magmas thermally equilibrated at their respective depths, whereas the sub-volcanic rocks were, as expected, significantly hotter than the adjacent crust.&lt;/p&gt;&lt;p&gt;By plotting the results on a P&amp;#8211;T&amp;#8211;X&lt;sub&gt;H2O&lt;/sub&gt; petrogenetic grid, and assuming adiabatic ascent through the crust, the sub-volcanic magmas appear to be drier (~3 wt% H&lt;sub&gt;2&lt;/sub&gt;O) than the granitic magmas (~7 wt% H&lt;sub&gt;2&lt;/sub&gt;O) which formed at greater depth. Monazite saturation temperatures (which depends on the water content, light&amp;#8211;REE content and composition of the granitic melt), are in agreement with the zircon thermometers only if water values of ~3 wt% H&lt;sub&gt;2&lt;/sub&gt;O and ~7 wt% H&lt;sub&gt;2&lt;/sub&gt;O are assumed for the upper crustal magmas and deeper magmas, respectively. Moreover, melt compositions extracted from a modelled pseudosection of a sillimanite-bearing metapelite, which was interpreted to be the typical source rock for the surrounding granites (P=5 kbar and T=690&amp;#176;C&amp;#8211;850&amp;#176;C), show comparable water content values.&lt;/p&gt;&lt;p&gt;The T&lt;sub&gt;mz&lt;/sub&gt; results provide independent evidence for the H&lt;sub&gt;2&lt;/sub&gt;O content in magmas, and we suggest that reconciling T&lt;sub&gt;zr&lt;/sub&gt; with T&lt;sub&gt;mz&lt;/sub&gt; is a new and independent way of constraining H&lt;sub&gt;2&lt;/sub&gt;O content in granitic magmas.&lt;/p&gt;

New insights into the Gondwana breakup at the Southern South America by apatite fission-track analyses

Apatite fission-track (AFT) analyses, applied to Southern Brazil and Uruguay samples, was employed aiming to understand the low temperature history of the Dom Feliciano Belt Segment. The Dom Feliciano Belt formed during the Neoproterozoic to Early Paleozoic, linked to the Brasiliano/Pan-African Orogeny. Twenty-four samples were dated, and confined track lengths of twenty samples were measured. The spatial distribution of ages shows three domains with different evolution cut by shear zones and, or suture zones in the Dom Feliciano Belt. The Western Domain exhibits AFT ages > 250 Ma (Permian to Devonian) while the Eastern Domain shows AFT ages < 230 Ma (Paleogene to Triassic). In the Central Domain, the AFT ages range from ∼196 to 130 Ma (Jurassic to Early Cretaceous). The thermal modeling in the domains revealed a complex evolution, with cooling and reheating phases, and a denudation of ∼2600 m. The AFT ages clearly postdate the Gondwanide, Paraná-Etendeka and Rio Grande Cone exhumation history of the Dom Feliciano Belt.

Regional Variation in the Wet Season of Northern Australia

Variability in the wet season of tropical northern Australia is examined over its main months, November–March, with a focus on zonal differences between the western, central, and eastern domains, which encompass the northern parts of Western Australia, Northern Territory, and Queensland, respectively. The seasonal progression of the wet season is similar across the region, with steadily increasing atmospheric moisture and rainfall into the core months of the monsoon, January and February, decreasing into March. This seasonal progression differs in the eastern domain, where there is an extension of premonsoonal conditions into December, and a delay of the onset of the monsoon until January. An analysis of TRMM precipitation features (PFs) reveals more intense convection during the premonsoon, steadily decreasing in intensity to much shallower convection by March, with a steady increase in the overall number of PFs throughout the wet season. Regionally, the intensity of PFs steadily decreases eastward across northern Australia with significantly weaker, shallower PFs over the eastern domain. Intraseasonal variability associated with the Madden–Julian oscillation (MJO) has a consistent impact on the rainfall and the total number of TRMM PFs across northern Australia, with both increasing and decreasing during the active and suppressed phases, respectively. However, regional variations in the effect of the MJO lead to radically different characteristics of PFs during the suppressed phases; intense convection and thunderstorms become more frequent over the western and central domains, while shallow PFs associated with the warm rain precipitation process increase in number over the eastern domain.

Neoproterozoic extension in the Greater Dharwar Craton: a reevaluation of the “Betsimisaraka suture” in MadagascarThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

The Precambrian shield of Madagascar is reevaluated with recently compiled geological data and new U–Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology. Two Archean domains are recognized: the eastern Antongil–Masora domain and the central Antananarivo domain, the latter with distinctive belts of metamafic gneiss and schist (Tsaratanana Complex). In the eastern domain, the period of early crust formation is extended to the Paleo–Mesoarchean (3.32–3.15 Ga) and a supracrustal sequence (Fenerivo Group), deposited at 3.18 Ga and metamorphosed at 2.55 Ga, is identified. In the central domain, a Neoarchean period of high-grade metamorphism and anatexis that affected both felsic (Betsiboka Suite) and mafic gneisses (Tsaratanana Complex) is documented. We propose, therefore, that the Antananarivo domain was amalgamated within the Greater Dharwar Craton (India + Madagascar) by a Neoarchean accretion event (2.55–2.48 Ga), involving emplacement of juvenile igneous rocks, high-grade metamorphism, and the juxtaposition of disparate belts of mafic gneiss and schist (metagreenstones). The concept of the “Betsimisaraka suture” is dispelled and the zone is redefined as a domain of Neoproterozoic metasedimentary (Manampotsy Group) and metaigneous rocks (Itsindro–Imorona Suite) formed during a period of continental extension and intrusive igneous activity between 840 and 760 Ma. Younger orogenic convergence (560–520 Ma) resulted in east-directed overthrusting throughout south Madagascar and steepening with local inversion of the domain in central Madagascar. Along part of its length, the Manampotsy Group covers the boundary between the eastern and central Archean domains and is overprinted by the Angavo–Ifanadiana high-strain zone that served as a zone of crustal weakness throughout Cretaceous to Recent times.

Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

This paper reviews the geodynamic evolution of the Belledonne, Grandes Rousses and Oisans massifs in the western Alps from Early Ordovician to Permian times. Three domains are distinguished. The eastern domain, which includes the NE Belledonne massif and the inner Oisans massif, records the subduction of the Central-European ocean along a NW dipping subduction zone. The western domain is marked by Cambro-Ordovician back-arc rifting (Chamrousse ophiolite) initiating the opening of the Rheic ocean. It was followed by Mid-Devonian obduction of the back-arc Chamrousse ophiolite, towards the NW in relation with the SE dipping subduction of the Saxo-Thuringian ocean. The central domain, including the SW part of the Belledonne massif, the Grandes Rousses massif and the outer Oisans massif, records the Devonian to Carboniferous orogenic activity that produced calc-alkaline magmatism, Mg-K granite intrusions and syn-collisional sedimentation related to Visean nappe stacking that we relate to the closure of the Saxo-Thuringian ocean. Based on tectonostratigraphic correlations we propose that these domains initially correspond to the northeastward extension of the Bohemian massif. During the late Carboniferous, the External Crystalline Massifs including Sardinia and Corsica were stretched towards the SW along the &gt; 600 km long dextral External Crystalline Massifs shear zone. Offset of the Saxo-Thuringian and eo-Variscan suture zones from the Bohemian massif to the ECM suggests a possible dextral displacement of about 300 km along the ECM shear zone.

Metamorphic rocks in the Antarctic Peninsula region

The distribution of metamorphic rocks in the Antarctic Peninsula region, new quantitative peak pressure–temperature data along the Antarctic Peninsula, and a literature review on the current knowledge of metamorphic conditions in the Antarctic Peninsula region have been compiled into a single metamorphic map. The pressure–temperature data for the Antarctic Peninsula indicate (1) burial of supracrustal rocks to low to mid-crustal depth along the eastern and western side of the Antarctic Peninsula and on some islands adjacent to the western side of the peninsula; (2) uplift of lower- to mid-crustal metamorphic rocks along major shear and fault zones; and (3) a reversed succession of metamorphic grades for the western domain of the Antarctic Peninsula region compared to the eastern domain along the Eastern Palmer Land Shear Zone (EPLSZ) of the Antarctic Peninsula. The metamorphic data are consistent with oblique convergence between Alexander Island (the Western Domain), Palmer Land (Central Domain) and the Gondwana margin (the Eastern Domain), supporting a model of (1) exhumation and shearing of the higher pressure rocks from central western (up to 9.4 kbar) and from northeast (7 kbar to 9 kbar) Palmer Land, (2) the exhumation and shearing of low to medium pressure rocks in western Palmer Land and along the Eastern Palmer Land Shear Zone, and (3) shallow burial and subsequent exhumation of sediments of the Gondwana margin along the Eastern Palmer Land Shear Zone. Based on the high-amphibolite grade rocks exposed in central western Palmer Land, our data also support earlier suggestions that the Eastern Palmer Land Shear Zone is the surface expression of a northwest- to west-dipping, deep-level, high-temperature crustal shear zone extending below the western part of the Central Domain of the Antarctic Peninsula.