Deformation of a High-Grade Gondwana Fragment, Sri Lanka

Kehelpannala, K.V. Wilbert

doi:10.1016/s1342-937x(05)70005-8

Cited by 74 publications

(93 citation statements)

References 51 publications

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“…The Kadugannawa Complex consisting of hornblende gneiss, biotite-hornblende gneiss and migmatites occurs within elongate synformal basins around Kandy in central Sri Lanka (Cooray, 1994). Although a number of petrological studies have been carried out later on this terrain (e.g., Kehelpannala, 1997;Mathavan et al, 1999;Mathavan and Fernando, 2001;Kröner et al, 2003;Kröner et al, 2013;Dharmapriya et al, 2014;Santosh et al, 2014;He et al, 2016a), lithological nomenclature and petrology of the terrain introduced by Cooray (1994) is widely recognized.…”

Section: Introductionmentioning

confidence: 99%

Internal texture and U–Th–total Pb isochron ages of monazite in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Wanniarachchi

Akasaka

2016

Journal of Mineralogical and Petrological Sciences

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The Chemical U-Th-total Pb isochron method (CHIME) dating was performed for internal domains and zones within monazites in garnet-biotite gneiss and garnet-biotite-cordierite gneiss from the Precambrian Southwestern Highland Complex (SWHC), Sri Lanka, to evaluate evolution of the metamorphic rocks which have been subjected to multiple thermal events during the Gondwana amalgamation. Monazites are abundant in garnetbiotite gneisses. The monazites have core-rim zoned, inherited core-bearing, complexly zoned, and oscillatory zoned type internal textures. The core domains of the core-rim zoned, inherited core-bearing, and complexly zoned type monazites show ages of 533-503, 1788-512, and 1686-678 Ma, respectively, and the rim domains show younger ages of 500-434 Ma. Even though its repeated zonings, oscillatory zoned type monazites show the only young age of 470 ± 45 Ma. The determined isochron ages are grouped into four clusters: group I of 1766 ± 140 and 1788 ± 30 Ma (at present 1686 ± 186 Ma age may be grouped into group I); group II of 679 ± 99 Ma; group III of ages in a range between 533 ± 22 and 481 ± 42 Ma; and group IV of ages in a range between 472 ± 17 and 433 ± 14 Ma. The ages of the group I may imply magma emplacement ages. The ages of the group II correspond to the stage of the most prominent thermal event recorded in the region. The groups III and IV can be identified as post-peak thermal events. The age data given for the monazites in the SWHC are consistent with the published data for the Central Highland Complex, and indicate that the SWHC has been subjected to the same thermal events as the Central Highland Complex.

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Section: Introductionmentioning

confidence: 99%

Internal texture and U–Th–total Pb isochron ages of monazite in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Wanniarachchi

Akasaka

2016

Journal of Mineralogical and Petrological Sciences

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“…posed and developed by Vitanage (1972), Voll and Kleinschrodt (1991), , Cooray (1994), Kriegsman (1995) and Kehelpannala (1997Kehelpannala ( , 2004 explained that two collisions have taken place, and the second collision caused the high-grade metamorphism in 630-500 Ma. This study on SWHC and previous studies on the CHC showed that zircon growth took place during 1900-1700 Ma.…”

Section: Formation Of Overgrowthsmentioning

confidence: 98%

“…The Kadugannawa Complex consisting of hornblende gneiss, biotitehornblende gneiss, and migmatites occurs within elongate synformal basins around Kandy in central Sri Lanka (Cooray, 1994). The terrain subdivision introduced by Cooray (1994) have been widely followed in a number of petrological studies (e.g., Kehelpannala, 1997;Mathavan et al, 1999;Mathavan and Fernando, 2001;Kröner et al, 2003;Kröner et al, 2013;Dharmapriya et al, 2014;Santosh et al, 2014;He et al, 2016aHe et al, , 2016b.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the studies on petrology, structural geology, and geochronology around the CHC, Vitanage (1972Vitanage ( , 1985 and Cooray (1994) defined the Wanni, Highland and Vijayan Complexes as discrete terranes, and a model implying that the Wanni and Highland Complexes collided at first and subsequently thrust over the Vijayan Complex was proposed (Vitanage, 1972;Voll and Kleinschrodt, 1991;Cooray, 1994;Kriegsman, 1995;Kehelpannala, 1997Kehelpannala, , 2004. On the other hand, Sajeev et al (2010) suggested that ultra hot collisional orogeny took place in the area of Sri Lanka in the process of assembly of Gondwana, and that the CHC was superheated by basaltic underplating followed by fast extensional exhumation.…”

Section: Introductionmentioning

confidence: 99%

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Internal textures and U–Pb geochronology of zircons in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Wanniarachchi

Akasaka

Hayasaka

et al. 2016

Journal of Mineralogical and Petrological Sciences

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Internal textures and U-Pb ages of zircons in garnet-biotite gneiss of the Southwestern Highland Complex (SWHC), Sri Lanka, were studied to clarify the repeated thermal events in the study area. The zircons from garnet-biotite gneiss consist of the detrital cores and overgrowths with two to five growth stages. The detrital zircon cores are rounded or euhedral to subhedral in shape, and show transgressive internal textures or oscillatory zoning.The rounded or subhedral to euhedral detrital core morphology suggests several major Archaean to Proterozoic sources of detritus zircons in the SWHC. Ages of the detrital cores are in a range of 3.3-1.7 Ga, and can be categorized into five ranges of 3380-3220, 2730-2660, 2550-2490, 2220-2170, and 1900-1700 Ma, implying the source rock ages. The detrital cores in the 3380-2170 Ma have Th/U-ratios of more than 0.3, suggesting igneous origin. The detrital cores in the range 1900-1700 Ma have Th/U of >0.3 or 0.3-0.1, suggesting an igneous or metamorphic origin. Some overgrowths with the ages in the ranges of 1900-1700 and 630-500 Ma have Th/U-ratios less than 0.1 implying that zircon growth corresponds to the thermal events. Zircons lacking detrital cores and having growth zones with characteristic metamorphic internal textures gave ages in a range of 630-500 Ma, implying the generation at the final granulite grade metamorphic event.

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“…Most of the meta-sediments in the WC occur close to the boundary with the HC (Kehelpannala 1997). Previous geochronological studies of the Wanni Complex yielded Nd model ages in the range of 1.0-2.0 Ga (Milisenda et al 1988(Milisenda et al , 1994.…”

Section: Geological Settingmentioning

confidence: 98%

Primary and secondary textures of dolomite in Eppawala carbonatites, Sri Lanka: implications for their petrogenetic history

Madugalla¹,

Pitawala²,

Manthilake³

2017

J. Geosci.

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Textural studies of carbonate minerals over the past three decades revealed that their textures are useful tool for understanding of petrogenesis of carbonatites. Petrographic, cathodoluminescence (CL) and electron-microprobe studies on textures of calcite and dolomite were performed for interpretation of evolution of Eppawala carbonatites in Sri Lanka. The studied carbonatites are dominated by calcite with subordinate dolomite. Calcites occur in two different morphological forms, reflecting two generations: as grains with dolomite inclusions (type-1) and dolomite-free (type-2) ones. Dolomites were subdivided into five distinct morphological types: randomly distributed, coarse-grained dolomite (type-1), rod--shaped or vermicular dolomite microcrysts within the type-1 calcite (type-2), inclusions of dolomite within the type 1 calcite forming plug-or wedge-shaped arrangements (type-3), dolomite microcrysts along the grain boundaries of the type 1 calcite (type-4) and clusters of dolomite crosscutting the type 1 calcite (type-5).The geochemical results indicate that these five morphological types accounts for three different generations of dolomites. Type-1 dolomite and type-1 calcite are interpreted as primary magmatic. Type-2 and type-3 represent exsolved dolomite formed by exsolution from type-1 calcite. Type-4 and type-5 dolomites are recrystallized and reorganized dolomites of exsolved type-2 and type-3 dolomites. Type-2 calcite reflects later recrystallization event. The composition of type-1 calcite indicates minimum temperatures of exsolution of c. 650 °C. The exsolution and recrystallization kinetics reflected the equilibration of carbonatite magma at two crustal depths during the petrogenesis of Eppawala carbonatite. The re-localization may have been related to the deformations experienced by the country rocks. : carbonatites, calcite, dolomite, exsolution, recrystallization Received: 15 March 2016; accepted: 24 August 2017; handling editor: V. Rapprich (Cooper and Reid 1991) have been well studied. Such studies revealed that textures of carbonate minerals are important tools to interpret the specific conditions of super cooling, cooling rates and super-saturation prevailing in the corresponding magmatic body. Additionally, the intergrowth textures of calcite and dolomite, where dolomite forms vermicules, plates, rods, segmented rods, blebs and xenomorphic grains have been reported from certain carbonatites (Van der Veen 1965;Zaitsev and Polezhaeva 1994). These textures yielded the composition of the primary carbonate phases, information on crystal-melt segregation and crystallization temperature as well as depth and timing of sub-solidus processes that have modified them (Van der Veen 1965;Cooper and Reid 1991;Wall et al. 1993;Zaitsev and Polezhaeva 1994). In the past several decades, intergrowth formation mechanisms have been subject to discussion. Exsolution (Goldsmith 1983;Puhan 1984) or metasomatism with recrystallization (Zaitsev and Polezhaeva 1994) could lead to the formation of such textures....

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Deformation of a High-Grade Gondwana Fragment, Sri Lanka

Cited by 74 publications

References 51 publications

Internal texture and U–Th–total Pb isochron ages of monazite in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Internal texture and U–Th–total Pb isochron ages of monazite in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Internal textures and U–Pb geochronology of zircons in metamorphic rocks from the Southwestern Highland Complex, Sri Lanka

Primary and secondary textures of dolomite in Eppawala carbonatites, Sri Lanka: implications for their petrogenetic history

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