Search results for "Batholith"
showing 5 items of 15 documents
Single zircon ages for two Archean banded migmatitic gneisses from central Zimbabwe
2004
We report new single zircon ages for two Archean banded gneisses from the Shangani Batholith in central Zimbabwe. The ages of ~2.77 and ~2.84 Ga do not support previous views that the area west of the current exposure of the Tokwe Segment was part of an early- to mid-Archean (>2.95 Ga) domain (Sebakwe Proto-craton). The data correspond to ~2.9 to 2.8 Ga dates for TTG granitoids of the Chingezi Suite. Members of this suite occur as intrusions within the south-central part of the Zimbabwe Craton and are associated with contemporaneous felsic volcanic rocks. On the basis of their age distribution, isotopic characteristics and outcrop pattern with respect to the Tokwe Segment, the formation of …
Timing and Evolution of Cretaceous Island Arc Magmatism in Central Cuba: Implications for the History of Arc Systems in the Northwestern Caribbean
2011
AbstractSHRIMP and conventional zircon dating place temporal constraints on the evolution of the Cretaceous Volcanic Arc system in central Cuba. The arc has a consistent stratigraphy across strike, with the oldest and deepest rocks in the south (in tectonic contact with the ∼5–10-km-wide Mabujina Amphibolite Complex [MAC]) and younger rocks in the north. The MAC is thought to represent the deepest exposed section of the Cretaceous Volcanic Arc and its oceanic basement in Cuba. We undertook a single zircon geochronological study of five gneisses and two amphibolites from the MAC and seven rocks from the Manicaragua Batholith, which intrudes both the MAC and the Cretaceous Volcanic Arc. A SHR…
Xenoliths from the sub-volcanic lithosphere of Mt Taranaki, New Zealand
2010
Abstract Mount Taranaki is located 140 km west of the Taupo Volcanic Zone and represents the most westerly expression of subduction-related volcanism on the North Island of New Zealand. Taranaki is a predominantly high-K arc volcano but compositions range from basaltic andesite to andesite with minor dacite and basalt. The sub-volcanic basement under Taranaki is thought to comprise calc–alkaline plutonic and metamorphic rocks of the Median Batholith, overlain by a sequence of Cretaceous and Tertiary sediments. Taranaki lavas contain abundant xenoliths that represent samples of the upper to lower crust beneath the volcano. The xenolith suite has been initially organised into six groups based…
Mesoproterozoic (Grenville-age) terranes in the Kyrgyz North Tianshan: Zircon ages and Nd–Hf isotopic constraints on the origin and evolution of base…
2013
Abstract The North Tianshan orogenic belt in Kyrgyzstan consists predominantly of Neoproterozoic to early Paleozoic assemblages and tectonically interlayered older Precambrian crystalline complexes and formed during early Paleozoic accretionary and collisional events. One of the oldest continental fragments of late Mesoproterozoic (Grenvillian) age occurs within the southern part of the Kyrgyz North Tianshan. Using SHRIMP zircon ages, we document two magmatic events at ~ 1.1 and ~ 1.3 Ga. The younger event is characterized by voluminous granitoid magmatism between 1150 and 1050 Ma and is associated with deformation and metamorphism. The older event is documented by ~ 1.3 Ga felsic volcanism…
Age, geodynamic setting, and mantle enrichment processes of a K-rich intrusion from the Meissen massif (northern Bohemian massif) and implications fo…
1997
The plutonic complex of the Meissen massif (northern margin of the Bohemian massif) comprises dioritic to mainly monzonitic and granitic rocks. The diorite to monzonite intrusions show major and trace element patterns typical for shoshonitic series. The chemical signatures of less crustally contaminated diorites are similar to arc-related shoshonitic rocks derived from continental lithospheric mantle (CLM) sources previously enriched by subduction of altered oceanic crust. Laser step heating 40Ar/39Ar analyses on actinolitic to edenitic amphiboles from geographically different occurrences of the monzonitic intrusion yielded concordant plateau ages as well as total gas ages ranging from 329.…