Triassic rift-related meta-granites in the Internal Hellenides, Greece

2009 ◽  
Vol 146 (2) ◽  
pp. 252-265 ◽  
Author(s):  
F. HIMMERKUS ◽  
T. REISCHMANN ◽  
D. KOSTOPOULOS
Keyword(s):  
Eastern Mediterranean ◽  
Primary Crystallization ◽  
Trace Element Geochemistry ◽  
Initial Ratio ◽  
Element Geochemistry ◽  
Northern Greece ◽  
The West ◽  
Basement Complex ◽  
Single Zircon ◽  
Zircon Evaporation

AbstractThe Serbo-Macedonian Massif is a basement complex in the Internal Hellenides of northern Greece, situated between the Vardar Zone to the west and the Rhodope Massif to the east. The Serbo-Macedonian Massif comprises several distinct basement units interpreted as terranes, the largest of which is the Gondwana-derived Vertiskos Terrane in the northwestern and central parts of the massif. A series of leucocratic meta-granites intrude the Silurian orthogneiss basement of the Vertiskos Terrane. No similar granites are found in any of the other units of the Internal Hellenides. The meta-granites have a pronounced crustal within-plate signature which is visible in lithology, major- and trace-element geochemistry and the Sr isotopic compositions. These intrusions were dated using the Pb–Pb single-zircon evaporation method, and yielded a Triassic age of between 240.7 ± 2.6 Ma and 221.7 ± 1.9 Ma on 17 samples, with a mean age of 228.3 ± 5.6 Ma. The zircons are purely magmatic, indicating that ages are primary crystallization ages. A Rb–Sr errorchron of the whole-rock samples of the Arnea granite yielded an age of 231.6 ± 9.9 Ma (MSWD = 82), and a mean 87Sr/86Sr initial ratio is 0.7142, indicating a crust-dominated source, and suggesting an A-type origin for the granites. The A-type meta-granites together with mafic intrusive bodies (amphibolites) in the Vertiskos Terrane may be evidence of Triassic rifting that led to the formation of a branch of Neotethys (Vardar–Meliata Ocean). Similar rock associations are also exposed in the Cyclades, and in massifs of the wider eastern Mediterranean realm related to the Gondwana-derived Hun Terrane, indicating that the Arnea-type granites are representatives of a major regional rifting event in Triassic times.

Developing a multi-methods dating framework for the Eastern Mediterranean region over the Late Quaternary

2020 ◽  
Author(s):  
Shuang Zhang ◽  
Christina Manning ◽  
Christopher Satow ◽  
Simon J Armitage ◽  
Simon Blockley
Keyword(s):  
Environmental Change ◽  
Trace Element ◽  
Late Quaternary ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Aegean Sea ◽  
Trace Element Geochemistry ◽  
Central Mediterranean ◽  
Element Geochemistry ◽  
The Mediterranean

<p>The Eastern Mediterranean is an important region for understanding the late Quaternary, as there is evidence for a complex pattern of climatic and environmental change, influenced by orbital forcing and complex feedback mechanisms (Rohling et al., 2013). It is also a key region for examining the dispersal of humans out of Africa. Consequently, it is important to develop robust chronologies for palaeoclimatic, environmental and archaeological records in the region, to allow synchronisation, comparison and hypothesis testing. Tephrochronology is a vital tool for correlating such records, but the fine detail of the Eastern Mediterranean tephra depositional history is not yet well defined. Part of the problem relates to a lack of cryptotephra (non-visible ash) studies on long stratigraphic records. It is well known from the Atlantic and Central Mediterranean that cryptotephra studies can significantly improve tephra inventories, and constrain the relationship between key tephra markers and important environmental transitions. Another key problem for the region is that for distal tephra there is a relatively limited geochemical database from different volcanic centres, especially in terms of trace element compositions. One important method for addressing this problem is to develop detailed tephrostratigraphic records and tephra geochemical inventories from long sediment sequences (e.g. Bourne et al., 2010; Satow et al., 2015).</p><p>Here we present the first marine crypto-tephrostratigraphy from the Levantine Sea, covering approximately the last ~200,000 years, from a long marine core (MD81-LC31). The new data for the core include tephra shard concentrations, major and trace element geochemistry, correlations to the eruptive record of the Aegean and Anatolian volcanic centres, and new radiometric age information. Our new data is compared to existing chronological information from LC-31, including sedimentological, geochemical, paleomagnetic and radiocarbon evidence. Our data helps to refine the chronology for this important record and will underpin ongoing studies into the detail of palaeoceanographic and environmental change in the region.</p><p> </p><p>Bourne, A.J., Lowe, J.J., Trincardi, F. et al. 2010. Distal tephra record for the last ca 105,000 years from core PRAD 1-2 in the central Adriatic Sea: implications for marine tephrostratigraphy. Quaternary Science Reviews, 29(23-24), 3079-3094.</p><p>Rohling, E.J., Grant, K.M., Roberts, A.P. et al. 2013. Paleoclimate variability in the Mediterranean and Red Sea regions during the last 500,000 years: implications for hominin migrations. Current Anthropology, 54(S8), S183-S201.</p><p>Satow, C., Tomlinson, E.L., Grant, K.M. et al. 2015. A new contribution to the Late Quaternary tephrostratigraphy of the Mediterranean: Aegean Sea core LC21. Quaternary Science Reviews, 117, 96-112.</p>

Single zircon U–Pb ages and geochemistry of granitoid gneisses from SW Poland: evidence for an Avalonian affinity of the Brunian microcontinent

2010 ◽  
Vol 147 (4) ◽  
pp. 508-526 ◽  
Author(s):  
STANISŁAW MAZUR ◽  
ALFRED KRÖNER ◽  
JACEK SZCZEPAŃSKI ◽  
KRZYSZTOF TURNIAK ◽  
PAVEL HANŽL ◽  
...  
Keyword(s):  
Age Groups ◽  
Trace Element Geochemistry ◽  
Variscan Belt ◽  
Element Geochemistry ◽  
Single Zircon ◽  
Sw Poland ◽  
Tectonic Contact ◽  
Late Neoproterozoic ◽  
Early Palaeozoic ◽  
Granitoid Gneisses

AbstractSeven granitoid gneisses from the contact zone between the eastern margin of the Variscan belt and the Brunian microcontinent in SW Poland have been dated by ion-microprobe and207Pb/206Pb single zircon evaporation methods. The zircons define two age groups for the gneiss protoliths: (1) late Neoproterozoicc.576–560 Ma and (2) early Palaeozoicc.488–503 Ma granites. The granitoid gneisses belonging to the basement of the Brunian microcontinent contain abundant Mesoproterozoic to latest Palaeoproterozoic inherited material in the range of 1200–1750 Ma. The gneisses of the Variscan crustal domain lack Mesoproterozoic inherited zircon cores. Trace element geochemistry of Proterozoic gneisses reveals features resembling either volcanic arc or post-collisional granites. The studied rocks are geochemically similar to other Proterozoic orthogneisses derived from the basement of the Brunian microcontinent. Gneisses with early Palaeozoic protolith ages are geochemically comparable to granitoid gneisses widespread in the adjacent Sudetic part of the Bohemian Massif and are considered characteristic of peri-Gondwanan crust. Our data prove the dissimilarity between the Brunia plate and the westerly terranes of the Variscan belt. The occurrence of granitic gneisses with late Neoproterozoic protolith ages and widespread Mesoproterozoic inheritance in our dated samples support an East Avalonian affinity for the Brunian microcontinent. In contrast, the abundance of gneisses derived from an early Palaeozoic granitic protolith and devoid of Mesoproterozoic zircon cores supports the Armorican affinity of the Variscan domain bordering on the Brunia plate from the west. Structural evidence shows that the eastern segment of the Variscan belt is juxtaposed against the Brunian microcontinent along a N–S-trending tectonic contact, possibly equivalent to the Rheic suture.

Trace element geochemistry of parts of the Closepet granite, Mysore State, India

1972 ◽  
Vol 38 (298) ◽  
pp. 678-686 ◽  
Author(s):  
V. Divakara Rao ◽  
U. Aswathanarayana ◽  
M. N. Qureshy
Keyword(s):  
Trace Element ◽  
Emission Spectroscopy ◽  
Vapour Phase ◽  
Trace Element Geochemistry ◽  
Initial Ratio ◽  
Element Geochemistry ◽  
Granite Magma ◽  
Peninsular Gneiss ◽  
Mysore State ◽  
Trace Element Contents

SummaryTrace elements in twenty samples of the Closepet granite (grey and pink varieties) and the related rocks have been determined by neutron activation analysis (Th, Rb, and Cs), fluorometry (U), flame-photometry (K), and emission spectroscopy (Pb, Sr). The trace element contents of the grey and pink varieties are generally similar. An analysis of the magnitudes of the trace element and other ratios (K/Rb, 235; Th/U, 6·4; U/K (× 104), 0·7; K/Cs (× 10−4), 3·6; Th/K (× 104), 5·3; Fe2O3/(FeO+Fe2O3), 0·27) as well as 87Sr/86Sr initial ratio (0·705; Crawford, 1969) of the Closepet granite indicate two possible modes of genesis: Either the granite magma was not highly differentiated and the vapour phase was relatively insignificant; the crystallization of the magma took place under essentially non-oxidizing conditions; the pink variety, which followed the grey variety, crystallized under essentially the same conditions as the grey variety. Or the Closepet granite had a two-stage history—palingenesis (starting from the Peninsular gneiss) and metasomatism involving the enrichment in K, Rb, Pb, and Th and depletion of Sr and Cs, among others.

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