| 1. |
|
|
| 2. |
- Mansurbeg, Howri, et al.
(författare)
-
Diagenetic evolution and porosity destruction of turbiditic hybrid arenites and siliciclastic sandstones of foreland basins: Evidence from the Eocene Hecho Group, Pyrenees, Spain
- 2009
-
Ingår i: Journal of Sedimentary Research. - : Society for Sedimentary Geology. - 1527-1404 .- 1938-3681. ; 79:9-10, s. 711-735
-
Tidskriftsartikel (refereegranskat)abstract
- This study aims to unravel the impact of diagenetic alterations on porosity loss of foreland-basin turbiditic hybrid arenites and associated siliciclastic sandstones of the Eocene Hecho Group (south-central Pyrenees, Spain). In this succession, hybrid arenites and calclithites are extensively cemented by mesogenetic calcite cement (delta O-18(VPDB) = -10.0 parts per thousand to -5.8 parts per thousand; T-h, mode = 80 degrees C salinity mode = 18.8 wt% eq. NaCl), Fe-dolomite (delta(18)(OVPDB) = -8.5 parts per thousand to -6.3 parts per thousand) and trace amounts of siderite. The extent of carbonate cementation is interpreted to be related to the amounts of extrabasinal and intrabasinal carbonate grains, which provided nuclei and sources for the precipitation and growth of carbonate cements. Other diagenetic alterations, such as pyrite and albitization, had no impact on reservoir quality. Scarce early diagenetic cements, coupled with abundant ductile carbonate and siliciclastic framework grains, have led to rapid porosity loss owing to compaction. Conversely, abundant quartz in the sandstones prevented rapid loss of porosity by mechanical compaction. Reservoir quality was affected by mesogenetic cementation by quartz overgrowths, calcite and dolomite intergranular pressure dissolution of quartz grains, and formation of fracture-filling calcite cement (delta O-18(V-PDB) values from -10.4 parts per thousand to -7.8 parts per thousand; T-h temperatures of approximate to 150 degrees C), which are attributed to deep circulation of hot meteoric waters during extensional stages of tectonism. The results of this study illustrate that diagenetic evolution pathways of the arenites and sandstones are closely linked to the variation in detrital composition, particularly the proportion and types of extrabasinal noncarbonates, extrabasinal carbonates, and intrabasinal carbonate grains. These insights suggest that marine turbiditic hybrid arenites and calclithites of foreland basins are subjected to more rapid and extensive porosity loss owing to compaction and cementation than associated siliciclastic sandstones. Degradation of reservoir quality makes these hybrid arenites, calclithites, and sandstones suitable as tight gas reservoirs, but only if fracture porosity and permeability develop during tectonic deformation.
|
|
| 3. |
- Mansurbeg, Howri, et al.
(författare)
-
Meteoric-water diagenesis in late Cretaceous canyon-fill turbidite reservoirs from the Espirito Santo Basin, eastern Brazil
- 2012
-
Ingår i: Marine and Petroleum Geology. - : Elsevier BV. - 0264-8172 .- 1873-4073. ; 37:1, s. 7-26
-
Tidskriftsartikel (refereegranskat)abstract
- Parameters controlling the diagenetic evolution of passive margin, marine turbidites, which are important targets of hydrocarbon exploration, are poorly constrained in the literature. This study aims to unravel the conditions of diagenesis and its impact on the reservoir quality evolution from late Cretaceous canyon-filling turbiditic sandstones of the onshore portion of Espirito Santo Basin, eastern Brazil. Kaolinization (delta O-18 = +13.3 parts per thousand to +15.2 parts per thousand; delta D = 96.6 parts per thousand to -79.6 parts per thousand) and dissolution of framework silicate grains is attributed to meteoric water incursion during eodiagenesis in response to a considerable fall in relative sea-level. Eogenetic alterations also include cementation by siderite (average delta O-18 = -72 parts per thousand; delta C-13 = +9.3 parts per thousand) and pyrite. Progressive sediment burial (present depths = 1530-2027 m) resulted in the formation of poikilotopic calcite, ferroan dolomite-ankerite (average delta O-18 = -7.9 parts per thousand; delta C-13 = +2.9 parts per thousand), minor amounts of quartz overgrowths and in partial dickitization of kaolinite. Isotopic values of calcite and dolomite-ankerite follow two trends of co-variance of delta C-13 with decreasing delta O-18 and increasing temperature. From a composition closer to marine (approximate to 0 parts per thousand), one trend goes towards positive delta C-13 values (up to +22.4 parts per thousand for calcite; +18.6 parts per thousand for dolomite-ankerite), indicating increasing input of carbonate from methanogenic fermentation. The other trend develops towards negative delta C-13 values (down to -17.2 parts per thousand for calcite; 15 parts per thousand for dolomite-ankerite), suggesting increasing contribution from thermal decarboxylation with increasing temperature and depth. Despite the presence of various cement types, mechanical compaction was more important than cementation in reducing depositional porosity in the onshore Urucutuca sandstones.
|
|
| 4. |
- Morad, Sadoon, et al.
(författare)
-
Hydrothermal alteration of magmatic titanite : Evidence from Proterozoic granitic rocks, Southeastern Sweden
- 2009
-
Ingår i: Canadian Mineralogist. - : Mineralogical Association of Canada. - 0008-4476 .- 1499-1276. ; 47:4, s. 801-811
-
Tidskriftsartikel (refereegranskat)abstract
- Magmatic titanite in Proterozoic granitic rocks from southeastern Sweden has been subjected to hydrothermal dissolution and replacement by finely crystalline Fe-dominant chlorite and TiO2 (± quartz ± calcite). These alteration patterns require the redistribution of the highly immobile Ti and At on the thin-section scale. The chloritization of titanite involved the formation of an intermediate Al-Fe-rich phase probably comprising intimately intergrown, submicroscopic chlorite and titanite. The creation of microporosity by the hydrothermal alteration of titanite may enhance the diffusive flux of matter, and hence the rate of reactions in granitic rocks. The alteration of titanite is most pronounced in red-stained granitic rock zones enriched in partly dissolved biotite and magnetite, which could have acted as local source of Al, Fe and Mg needed for chlorite formation.
|
|
| 5. |
- Morad, Sadoon, et al.
(författare)
-
Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden
- 2010
-
Ingår i: Geological Journal. - : Wiley. - 0072-1050 .- 1099-1034. ; 45:1, s. 105-116
-
Tidskriftsartikel (refereegranskat)abstract
- Petrographic examinations and electron microprobe analyses of Proterozoic granitic rocks, SE Sweden aimed to characterize and unravel the mechanisms and conditions of plagioclase alterations. These alterations include saussuritization, albitization and replacement of plagioclase by K-feldspar. The hydrothermal alterations, which are inferred to have occurred at ca. 250-400°C, resulted in concomitant formation of Alrich titanite, epidote, calcite, pumpellyite, prehnite and iron oxides. Replacement of plagioclase by K-feldspar occurs in red-stained zones, which have developed close to thin fractures owing to the precipitation of tiny Fe-oxide pigment particles within the altered plagioclase, whereas saussuritized plagioclase has less systematic spatial relationships to these fractures. Albitization of plagioclase occurred in rocks that are poor in biotite compared to rocks that suffered extensive saussuritization. The chemical and textural characterization of various types of plagioclase alterations allows elucidation of the granitic hydrothermal systems. Features of feldspar alteration in the granitic rocks are similar to those encountered in feldspathic sandstones and should hence be considered in studies on diagenetic changes of siliciclastic successions during basin evolution.
|
|
| 6. |
- Mansurbeg, Howri, et al.
(författare)
-
Diagenesis and reservoir quality evolution of paleocene deep-water, marine sandstones, the Shetland-Faroes Basin, British Continental Shelf
- 2008
-
Ingår i: Marine and Petroleum Geology. - : Elsevier BV. - 0264-8172 .- 1873-4073. ; 25:6, s. 514-543
-
Tidskriftsartikel (refereegranskat)abstract
- The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite (δ18OV−PDB=−10.9‰ and −3.8‰), trace amounts of non-ferroan dolomite, siderite (δ18OV−PDB=−14.4‰ to −0.6‰), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite (δ18OV−PDB=−12.9‰ to −7.8‰) and Fe-dolomite/ankerite (δ18OV−PDB=−12.1‰ to −6.3‰) at temperatures of 50–140 and 60–140 °C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive eogenetic kaolinite, smectite and mesogenetic illite and chlorite. Kaolinite has been subjected to mesogenetic replacement by dickite. The K-feldspar and plagioclase grains have been albitized. Dissolution of calcite cement and of framework grain (feldspar, volcanic fragments and mud intraclasts) has resulted in a considerable enhancement of reservoir quality.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Moreno-Càceres, J, et al.
(författare)
-
Caveolin-1 is required for TGF-β-induced transactivation of the EGF receptor pathway in hepatocytes through the activation of the metalloprotease TACE/ADAM17
- 2014
-
Ingår i: Cell Death and Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor-beta (TGF-β) plays a dual role in hepatocytes, inducing both pro- and anti-apoptotic responses, whose balance decides cell fate. Survival signals are mediated by the epidermal growth factor receptor (EGFR) pathway, which is activated by TGF-β in these cells. Caveolin-1 (Cav1) is a structural protein of caveolae linked to TGF-β receptors trafficking and signaling. Previous results have indicated that in hepatocytes, Cav1 is required for TGF-β-induced anti-apoptotic signals, but the molecular mechanism is not fully understood yet. In this work, we show that immortalized Cav1(-/-) hepatocytes were more sensitive to the pro-apoptotic effects induced by TGF-β, showing a higher activation of caspase-3, higher decrease in cell viability and prolonged increase through time of intracellular reactive oxygen species (ROS). These results were coincident with attenuation of TGF-β-induced survival signals in Cav1(-/-) hepatocytes, such as AKT and ERK1/2 phosphorylation and NFκ-B activation. Transactivation of the EGFR pathway by TGF-β was impaired in Cav1(-/-) hepatocytes, which correlated with lack of activation of TACE/ADAM17, the metalloprotease responsible for the shedding of EGFR ligands. Reconstitution of Cav1 in Cav1(-/-) hepatocytes rescued wild-type phenotype features, both in terms of EGFR transactivation and TACE/ADAM17 activation. TACE/ADAM17 was localized in detergent-resistant membrane (DRM) fractions in Cav1(+/+) cells, which was not the case in Cav1(-/-) cells. Disorganization of lipid rafts after treatment with cholesterol-binding agents caused loss of TACE/ADAM17 activation after TGF-β treatment. In conclusion, in hepatocytes, Cav1 is required for TGF-β-mediated activation of the metalloprotease TACE/ADAM17 that is responsible for shedding of EGFR ligands and activation of the EGFR pathway, which counteracts the TGF-β pro-apoptotic effects. Therefore, Cav1 contributes to the pro-tumorigenic effects of TGF-β in liver cancer cells.
|
|
