Multiphase dolomitization in the Jutana Formation (Cambrian), Salt Range (Pakistan): Evidences from field observations, microscopic studies and isotopic analysis
Fuente:
Redalyc
Guardado en:
| Autor principal: | |
|---|---|
| Formato: | Artículo científico |
| Lenguaje: | en |
| Publicado: |
Universitat de Barcelona
2019
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1876489905079582720 |
|---|---|
| author | S. Khan |
| author_facet | S. Khan |
| contents | Multiphase dolomitization in the Jutana Formation (Cambrian), Salt Range (Pakistan): Evidences from field observations, microscopic studies and isotopic analysis S. Khan M.M. Shah Ciencias de la Tierra Mg isotopes Salt Range C isotiopes Cambrian dolomite Excellent dolomite exposures are observed in the eastern Salt Range (Pakistan), where the Cambrian Jutana Formation consists of two distinct units (i.e. oolitic – pisolitic unit and massive dolomite unit). Field observations revealed that the lower, oolitic-pisolitic unit mostly comprises medium to thick bedded, interlayered brown yellowish dolostone containing ooids/pisoids and faunal assemblages, and grey whitish sandstone with distinct depositional sedimentary features (i.e. trough-, herringbone- and hummocky-cross bedding). The upper massive dolostone unit consists of thick bedded to massive dolostone. These two units are separated by shale. Petrographic studies identified three dolomite types, which include: fine crystalline dolomite (Dol. I), medium-coarse crystalline dolomite (Dol. II) and fracture associated, coarse crystalline dolomite (Dol. III). Stable isotope studies indicate less depleted δ18O values for Dol. I (-6.44 to -3.76‰V-PDB), slightly depleted δ18O values for Dol. II (-7.73 to -5.24‰V-PDB) and more depleted δ18O values for Dol. III (-7.29 to -7.20‰V-PDB). The δ13C values of the three dolomite phases are well within the range of Cambrian sea-water signatures. Furthermore, δ26Mg-δ25Mg signatures (Dol. I; δ26Mg=-1.19 to -1.67, δ25Mg=-0.61 to -0.86 and Dol. II; δ26Mg=-1.34 to -1.59, δ25Mg=-0.70 to -0.83) indicate three phases of dolomitization in different diagenetic settings. First, an initial stage of dolomitization during the early Cambrian resulted from altered marine, Mg-rich fluids associated with mixing zone mechanism. Second, a late stage of dolomitization was associated with burial during late Permian. A third dolomitization phase was related to post-Eocene times. 2019 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50558790003 https://www.redalyc.org/journal/505/50558790003/ https://www.redalyc.org/journal/505/50558790003/html/ https://www.redalyc.org/journal/505/50558790003/50558790003.epub https://www.redalyc.org/journal/505/50558790003/movil https://doi.org/10.1344/GeologicaActa2019.17.2 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Vol.17 |
| format | Artículo científico |
| id | redalyc_50558790003 |
| institution | Redalyc |
| language | en |
| publishDate | 2019 |
| publisher | Universitat de Barcelona |
| spellingShingle | Multiphase dolomitization in the Jutana Formation (Cambrian), Salt Range (Pakistan): Evidences from field observations, microscopic studies and isotopic analysis S. Khan Ciencias de la Tierra Mg isotopes Salt Range C isotiopes Cambrian dolomite Multiphase dolomitization in the Jutana Formation (Cambrian), Salt Range (Pakistan): Evidences from field observations, microscopic studies and isotopic analysis S. Khan M.M. Shah Ciencias de la Tierra Mg isotopes Salt Range C isotiopes Cambrian dolomite Excellent dolomite exposures are observed in the eastern Salt Range (Pakistan), where the Cambrian Jutana Formation consists of two distinct units (i.e. oolitic – pisolitic unit and massive dolomite unit). Field observations revealed that the lower, oolitic-pisolitic unit mostly comprises medium to thick bedded, interlayered brown yellowish dolostone containing ooids/pisoids and faunal assemblages, and grey whitish sandstone with distinct depositional sedimentary features (i.e. trough-, herringbone- and hummocky-cross bedding). The upper massive dolostone unit consists of thick bedded to massive dolostone. These two units are separated by shale. Petrographic studies identified three dolomite types, which include: fine crystalline dolomite (Dol. I), medium-coarse crystalline dolomite (Dol. II) and fracture associated, coarse crystalline dolomite (Dol. III). Stable isotope studies indicate less depleted δ18O values for Dol. I (-6.44 to -3.76‰V-PDB), slightly depleted δ18O values for Dol. II (-7.73 to -5.24‰V-PDB) and more depleted δ18O values for Dol. III (-7.29 to -7.20‰V-PDB). The δ13C values of the three dolomite phases are well within the range of Cambrian sea-water signatures. Furthermore, δ26Mg-δ25Mg signatures (Dol. I; δ26Mg=-1.19 to -1.67, δ25Mg=-0.61 to -0.86 and Dol. II; δ26Mg=-1.34 to -1.59, δ25Mg=-0.70 to -0.83) indicate three phases of dolomitization in different diagenetic settings. First, an initial stage of dolomitization during the early Cambrian resulted from altered marine, Mg-rich fluids associated with mixing zone mechanism. Second, a late stage of dolomitization was associated with burial during late Permian. A third dolomitization phase was related to post-Eocene times. 2019 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50558790003 https://www.redalyc.org/journal/505/50558790003/ https://www.redalyc.org/journal/505/50558790003/html/ https://www.redalyc.org/journal/505/50558790003/50558790003.epub https://www.redalyc.org/journal/505/50558790003/movil https://doi.org/10.1344/GeologicaActa2019.17.2 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Vol.17 |
| title | Multiphase dolomitization in the Jutana Formation (Cambrian), Salt Range (Pakistan): Evidences from field observations, microscopic studies and isotopic analysis |
| topic | Ciencias de la Tierra Mg isotopes Salt Range C isotiopes Cambrian dolomite |
| url | https://www.redalyc.org/articulo.oa?id=50558790003 https://www.redalyc.org/journal/505/50558790003/ https://www.redalyc.org/journal/505/50558790003/html/ https://www.redalyc.org/journal/505/50558790003/50558790003.epub https://www.redalyc.org/journal/505/50558790003/movil https://doi.org/10.1344/GeologicaActa2019.17.2 |