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Bouilhol P.,ETH Zurich | Bouilhol P.,Massachusetts Institute of Technology | Schaltegger U.,University of Geneva | Chiaradia M.,University of Geneva | And 4 more authors.
Chemical Geology | Year: 2011

The combination of age determination and geochemical tracers allows understanding the source evolution during magmatism. We studied the Sapat Complex, in the exhumed Cretaceous Kohistan Paleo-Island Arc, to reconstruct the formation of the juvenile lower arc crust and the evolution of the mantle source during arc magmatism. High precision ID-TIMS U/Pb dating on zircon, shows that a protracted period of magmatic accretion formed the Sapat Complex between 105 and 99. Ma. Since continued melt percolation processes that formed the lower crust obscured the original bulk rock Nd-Pb-Sr isotopic composition, we rely on the Hf isotopic composition of zircons of different ages to unravel the source evolution. Nd and Pb bulk isotopic compositions coupled with Hf isotopic composition on zircons allow reconstructing a geodynamical scenario for the Sapat Complex, and the Cretaceous history of the Arc. We suggest that trenchward migration of the hot mantle source at 105. Ma explains the small heterogeneous εHf signal between +. 14 and +. 16. This heterogeneity vanished within ca. 2 million. years, and the εHf of the source evolved from +. 16 to +. 14 at 99. Ma. Integrated to the Kohistan Cretaceous history, which has a baseline of εHf ≈ 14, these data pinpoint two geodynamical events, with slab retreat and the formation of the Sapat Complex followed by splitting of the Kohistan island arc at 85. Ma. © 2010 Elsevier B.V.


Jagoutz O.,Massachusetts Institute of Technology | Schmidt M.W.,ETH Zurich | Enggist A.,ETH Zurich | Enggist A.,Australian National University | And 3 more authors.
Contributions to Mineralogy and Petrology | Year: 2013

We present the geochemistry and intrusion pressures of granitoids from the Kohistan batholith, which represents, together with the intruded volcanic and sedimentary units, the middle and upper arc crust of the Kohistan paleo-island arc. Based on Al-in-hornblende barometry, the batholith records intrusion pressures from ~0.2 GPa in the north (where the volcano-sedimentary cover is intruded) to max. ~0.9 GPa in the southeast. The Al-in-hornblende barometry demonstrates that the Kohistan batholith represents a complete cross section across an arc batholith, reaching from the top at ~8-9 km depth (north) to its bottom at 25-35 km (south-central to southeast). Despite the complete outcropping and accessibility of the entire batholith, there is no observable compositional stratification across the batholith. The geochemical characteristics of the granitoids define three groups. Group 1 is characterized by strongly enriched incompatible elements and unfractionated middle rare earth elements (MREE)/heavy rare earth element patterns (HREE); Group 2 has enriched incompatible element concentrations similar to Group 1 but strongly fractionated MREE/HREE. Group 3 is characterized by only a limited incompatible element enrichment and unfractionated MREE/HREE. The origin of the different groups can be modeled through a relatively hydrous (Group 1 and 2) and of a less hydrous (Group 3) fractional crystallization line from a primitive basaltic parent at different pressures. Appropriate mafic/ultramafic cumulates that explain the chemical characteristics of each group are preserved at the base of the arc. The Kohistan batholith strengthens the conclusion that hydrous fractionation is the most important mechanism to form volumetrically significant amounts of granitoids in arcs. The Kohistan Group 2 granitoids have essentially identical trace element characteristics as Archean tonalite-trondhjemite-granodiorite (TTG) suites. Based on these observations, it is most likely that similar to the Group 2 rocks in the Kohistan arc, TTG gneisses were to a large part formed by hydrous high-pressure differentiation of primitive arc magmas in subduction zones. © 2013 Springer-Verlag Berlin Heidelberg.


Sahreen S.,Pakistan Museum of Natural History | Khan M.R.,Quaid-i-Azam University | Khan R.A.,Sudan University of Science and Technology
Oxidative Medicine and Cellular Longevity | Year: 2013

Effect of methanolic extract of Rumex hastatus roots (MRR) and its derived fractions, n-hexane (HRR), ethyl acetate (ERR), chloroform (CRR), butanol (BRR), and aqueous extract (ARR), was studied against carbon tetrachloride (CCl 4) induced hepato and testicular toxicity in rats. Intraperitoneal dose of 20 percent CCl4 (0.5 ml/kg bw) was administered twice a week for eight weeks to a group of rats. Other groups were given CCl4 and various fractions of R. hastatus roots (200 mg/kg bw). CCl4 treatment depleted glutathione contents and activities of antioxidant enzymes while increased the concentration of lipid peroxides (TBARS) along with corresponding DNA injuries and histopathological damages. Supplementation with various fractions of R. hastatus roots (200 mg/kg body weight) attenuated the toxicity of CCl4 in liver and testis tissues through improvement in the serological, enzymatic, and histological parameters towards the normal. Posttreatment of R. hastatus roots (200 mg/kg body weight) also reversed the alteration in reproductive hormonal secretions and DNA damages in CCl 4 treated rats. The results clearly demonstrated that R. hastatus treatment augments the antioxidants defense mechanism and provides the evidence that it may have a therapeutic role in free radical mediated diseases. © 2013 Sumaira Sahreen et al.


Sahreen S.,Pakistan Museum of Natural History | Sahreen S.,Sudan University of Science and Technology | Khan M.R.,Sudan University of Science and Technology | Khan R.A.,Sudan University of Science and Technology
BMC Complementary and Alternative Medicine | Year: 2014

Background: Carissa opaca is a Pakistani fruit, traditionally used in the treatment of various human ailments including asthma and pulmonary damage. The present study investigated the protective effects of Carissa opaca against CCl4-induced oxidative stress in rat lungs. Methods: To assess the protective effects of Carissa opaca, 42 Sprague-Dawley male rats (170-180 g) were randomly divided into 7 groups. Group I was untreated and group II received olive oil intraperitoneally (i.p.) and dimethyl sulfoxide orally. Groups III, IV, V, VI and VII were administered CCl4, 3 ml/kg bodyweight (30% in olive oil i.p.). Group IV was administered 50 mg/kg bodyweight silymarin whereas groups V, VI and VII were treated with 200 mg/kg of various fractions of Carissa opaca after 48 h of CCl4 treatment for eight weeks. Antioxidant profiles in lungs were evaluated by estimating the activities of antioxidant enzymes: catalase, peroxidase, superoxide dismutase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, quinone reductase and reduced glutathione. CCl4-induced lipid peroxidation was determined by measuring the level of thiobarbituric acid reactive substances (TBARS) with conjugation of DNA damage and histopathology. Results: Administration of CCl4 for 8 weeks significantly reduced (p < 0.05) the activities of antioxidant enzymes and GSH concentration while increasing TBARS content and DNA damage. Co-treatment of various fractions of Carissa opaca and silymarin restored the activities of antioxidant enzymes and glutathione content. Changes in TBARS concentration and DNA fragmentation was significantly decreased (p < 0.05) following Carissa opaca and silymarin treatment in lung. Conclusions: Histopathological changes in rat lungs induced by CCl4 were significantly restored by co-treatment with Carissa opaca and silymarin. © 2014 sahreen et al.; licensee BioMed Central Ltd.


Sahreen S.,Pakistan Museum of Natural History | Sahreen S.,Quaid-i-Azam University | Khan M.R.,Quaid-i-Azam University | Khan R.A.,Quaid-i-Azam University | Khan R.A.,Sudan University of Science and Technology
BMC Complementary and Alternative Medicine | Year: 2014

Background: Roots of Rumex hastatus (Polygonaceae) are traditionally used for the treatment of various ailments including liver and lung diseases. In this study, various solvent extracts of R. hastatus roots, like methanolic, n-hexane, ethyl acetate, chloroform, butanol and aqueous fractions were assessed through their antioxidant properties in vitro and determination of phenolic contents.Methods: Several parameters like DPPḢ , ABTṠ +, ̇ OH, H2O2, superoxide free radical scavenging, iron chelating power, reducing power, β-carotene bleaching power, antioxidant capacity and total phenolics and flavonoids were evaluated. High Performance liquid Chromatography (HPLC) was also considered.Results: Though all the fractions exhibited dose dependant activity. The samples with the highest activity were the butanol and methanol fractions in all the assays except hydrogen peroxide radical scavenging assay where chloroform fraction showed the highest scavenging aptitude. On the other hand, aquous fraction showed significant beta carotene linoleic acid, while n-hexane and ethyl acetate fractions exhibited a lesser antioxidant activity in all the assays. HPLC revealed the presence of rutin, luteolin-7-glucoside, vitexin and luteolin.Conclusion: These results have to some extent substantiated the use of R. hastatus roots against different diseases, as an excellent basis of potential antioxidant due to the presence of sufficient amount of phenolics such as rutin and luteolin. © 2014 Sahreen et al.; licensee BioMed Central Ltd.


Khan R.A.,Sudan University of Science and Technology | Khan R.A.,Quaid-i-Azam University | Khan M.R.,Quaid-i-Azam University | Sahreen S.,Pakistan Museum of Natural History | Ahmed M.,Sudan University of Science and Technology
Chemistry Central Journal | Year: 2012

Background: Launaea procumbens (LP) has been used as a food supplement in Pakistan. In this study methanolic crude extract (LPME) of the whole plant and its different fractions; n-hexane (LPHE); ethyl acetate (LPEE) and chloroform (LPCE) were studied for the determination of total flavonoid and phenolics contents along with multifaceted in vitro scavenging assays.Results: Considerable amount of flavonoid and phenolics contents were found in all the fractions. Methanol and chloroform fraction exhibited efficient scavenging of DPPH·, ABTS·+, ·OH, superoxide, lipid peroxide and nitric oxide free radicals. Significant correlation was found between DPPH·, ABTS·+, superoxide radical, β-carotene bleaching restraint and phosphomolybdenum assay with total flavonoids and phenolics contents. High performance chromatography (HPLC) of LPME revealed the presence of vitexin, orientin, rutin, hyperoside, catechin and myricetin.Conclusion: These results reveal the presence of bioactive compounds in LPME, which might be contributed towards the various in vitro scavenging. © 2012 Khan et al.; licensee Chemistry Central Ltd.


Khan R.A.,Sudan University of Science and Technology | Khan M.R.,Quaid-i-Azam University | Sahreen S.,Pakistan Museum of Natural History
BMC Complementary and Alternative Medicine | Year: 2012

Background: Rutin, a polyphenolic flavonoid, was investigated for its protective effects against the KBrO3 induced renal injuries in rat.Methods: Group I was control (untreated), group II was given saline 0.5 ml/kg bw (0.9% NaCl), group III was administered KBrO3 (20 mg/kg bw) intragastric twice a week for four weeks. Rutin was administered to group VI (50 mg/kg bw) and Group V (70 mg/kg bw) along with KBrO3 (20 mg/kg bw) while group VI was given rutin (70 mg/kg bw) alone twice a week for four weeks. Protective effects of rutin on KBrO3-induced nephrotoxicity in rats were determined for biochemical parameter of urine, and serum, various antioxidant enzymes, DNA and histopathological damages in kidneys.Results: The level of urinary red blood cells, leucocytes count, specific gravity, urea, creatinine and urobilinogen was increased (P<0.01) whereas creatinine clearance was reduced. Serum level of protein, albumin, globulin, nitrite, creatinine and blood urea nitrogen (BUN) was significantly increased (P<0.01) by KBrO3. Marked histopathological lesions, elevated DNA fragmentation and AgNORs count in renal tissues was determined. Activity of antioxidant enzymes; catalase, superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, and reduced glutathione contents were decreased (P<0.01) while thiobarbituric acid reactive substances were increased (P<0.01) with KBrO3 treatment in kidneys. DNA ladder assay was intimately related with the DNA fragmentation assay. Telomerase activity was found positive in the KBrO3 treated kidneys. Treatment with rutin effectively ameliorated the alterations in the studied parameters of rat. Rutin administration alone to rats did not exhibit any significant change in any of the parameters studied.Conclusion: These results suggest that rutin works as an antioxidant in vivo by scavenging reactive oxygen species and this serves to prevent oxidative renal damage in rat treated with KBrO3. © 2012 Khan et al.; licensee BioMed Central Ltd.


Hermann E.,University of Zürich | Hochuli P.A.,University of Zürich | Bucher H.,University of Zürich | Bruhwiler T.,University of Zürich | And 3 more authors.
Gondwana Research | Year: 2011

The impact of the end-Permian mass extinction on terrestrial ecosystems is still highly controversial. Here, new high-resolution palynological data from biostratigraphically well-dated Upper Permian to Middle Triassic successions of the Salt Range and Surghar Range (Pakistan) are presented. Our results reveal seven successive floral phases between the Late Permian and the Middle Triassic. At the onset of the Mesozoic, the flora is characterised by high abundances of lycopods associated with pteridosperms and conifers. This association prevails up to the middle Smithian and is followed by a prominent spore spike similar to the global spore spike reported from the Permian-Triassic boundary. Like that of the end-Permian, the middle Smithian spore spike is associated with a negative isotope excursion and is succeeded by a major marine faunal extinction event in the late Smithian. The recurrent patterns observed at the Permian-Triassic boundary and in the middle-upper Smithian suggest a common cause such as massive ejections of volcanic gases. The increasing abundance of conifers still associated with common lycopods in the Spathian suggests fading volcanically induced environmental perturbations and stabilisation of terrestrial ecosystems ca. 2.1. My after the end-Permian event. © 2011 Elsevier B.V.


Masroor R.,Pakistan Museum of Natural History
Pakistan Journal of Zoology | Year: 2011

An updated checklist of amphibians and reptiles that occur in the Margalla Hills National Park (MHNP) is provided. The information provided is based on the collections and observations made in the field from 2003 to 2009. Due to its geographic position of being situated at the junction of high mountains in the north and the southern plains, the park exhibits a diverse herpetofauna. So far, forty one species have been identified as occurring in the park, including nine species of amphibians and 32 species of reptiles. Three species of lizards viz., Laudakia agrorensis, Asymblepharus himalayanus, and Ophisops jerdonii are being reported for the first time from this park. © 2011 Zoological Society of Pakistan.


Hermann E.,University of Zürich | Hochuli P.A.,University of Zürich | Bucher H.,University of Zürich | Roohi G.,Pakistan Museum of Natural History
Review of Palaeobotany and Palynology | Year: 2012

Independently dated palynostratigraphic zonations of Early Triassic age are rare. One of the best places to study Late Permian to Middle Triassic palynology together with contemporaneous marine faunas is the sedimentary successions of the Salt Range and Surghar Range in Pakistan. Here, we present a new palynostratigraphic zonation of the Lower Triassic succession of North Gondwana, based on the spore pollen records of the Chhidru Formation, the Mianwali Formation, and the Tredian Formation from sections of the Nammal, Chhidru, Chitta-Landu and Narmia gorges in Pakistan. Within the Lower Triassic succession five palynological biozones are recognised, formally described, and calibrated by ammonoid biostratigraphy and C-isotope chemostratigraphy. Three further palynological associations, two from the uppermost Permian Chhidru Formation, and one from the Middle Triassic Tredian Formation, are informally described. The two basal assemblages (Chhidru 1 and Chhidru 2) are present in the uppermost Chhidru Formation. Chhidru 1 is dominated by gymnosperm pollen, whereas Chhidru 2 is characterised by abundant cavate trilete spores associated with conifer and pteridosperm pollen of Permian affinity. The assemblages of Dienerian to early Smithian age, the Densoisporites spp.- Lundbladispora spp. Assemblage Zone (PTr 1) and the Lundbladispora spp.- Densoisporites spp. Assemblage Zone (PTr 2) are dominated by cavate trilete spores. Compared to PTr 1, ornamented spores are more diverse in PTr 2, and taeniate bisaccate pollen are more abundant. The middle Smithian assemblages of the Densoisporites spp. Abundance Zone (PTr 3) are marked by an acme of Densoisporites spp. The following assemblages of the upper Smithian to lower Spathian Lunatisporites spp.- Densoisporites spp. Assemblage Zone (PTr 4) are characterised by abundant taeniate bisaccate pollen. The Spathian and Anisian assemblages (PTr 5 and Tredian 1) are characterised by abundant non-taeniate bisaccate pollen, and the common occurrence of Aratrisporites spp., and by generally diverse spore assemblages. The new palynostratigraphic zonation can be correlated with several other Gondwanan records (Australia, India, and Madagascar), and allows for reassessment of the floral recovery patterns in the aftermath of the end-Permian event. During periods with relatively stable carbon isotope values (early Smithian, Spathian and Anisian) pulses of diversification have been observed. During episodes of rapid fluctuations of the carbon cycle reduced palynofloral diversity is combined with rapid changes in the quantitative distribution pattern within the palynological assemblages. © 2011 Elsevier B.V.

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