Large Igneous Provinces of the Amazonian Craton and their Metallogenic Potential in Proterozoic Times

2021 ◽  
pp. SP518-2021-7
Author(s):  
N. J. Reis ◽  
W. Teixeira ◽  
M. S. D'Agrella-Filho ◽  
J. S. Bettencourt ◽  
R. E. Ernst ◽  
...  
Keyword(s):  
Mineral Resources ◽  
Large Igneous Provinces ◽  
Geologic Time ◽  
Magmatic Rocks ◽  
Igneous Provinces ◽  
Amazonian Craton ◽  
Geologic Time Scale ◽  
Felsic Volcanic ◽  
Geochemical Constraints ◽  
Magmatic Event

AbstractThis paper overviews the Proterozoic Large Igneous Provinces of the Amazonian Craton, characterized by large volumes of extrusive and intrusive magmatic rocks. We reassess the geologic, geochronologic and geochemical information to stablish three intracontinental felsic volcanic-plutonic igneous belts (i.e., SLIPs), namely: Orocaima (1.98-1.96 Ga), Uatumã (1.88-1.87 Ga) and Alta Floresta (1.80-1.79 Ga). The Avanavero LIP (1.79-1.78 Ga), as well as the Rincón del Tigre-Huanchaca LIP (1.11 Ga) are also revisited. The relationships of these events with intraplate settings through time and space are apparent. We examine the main characteristics of each magmatic event in light of the U-Pb zircon and baddeleyite ages and coupled isotopic-geochemical constraints, the geodynamic significance, and metallogenetic potential. The Uatumã and Alta Floresta SLIPs host the most important mineral resources within the Amazonian Craton. Global barcode matches of the Proterozoic SLIPS/LIP events of Amazonia are also addressed, as well as their possible links with geologic time-scale periods: the Orosirian, Statherian and Stenian boundaries. We also evaluate the available paleomagnetic data to address issues related to the barcode match of such SLIP/LIP events in the context of supercontinent cycles.

scholarly journals Petrogenesis and Geodynamic Implications of Miocene Felsic Magmatic Rocks in the Wuyu Basin, Southern Gangdese Belt, Qinghai-Tibet Plateau

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 655
Author(s):  
Hanzhi Chen ◽  
Mingcai Hou ◽  
Fuhao Xiong ◽  
Hongwei Tang ◽  
Gangqiang Shao
Keyword(s):  
Lower Crust ◽  
Volcanic Rocks ◽  
Tibet Plateau ◽  
Southern Tibet ◽  
Mixed Product ◽  
Good Opportunity ◽  
Magmatic Rocks ◽  
Adakitic Rocks ◽  
Felsic Volcanic ◽  
Qinghai Tibet Plateau

Miocene felsic magmatic rocks with high Sr/Y ratios are widely distributed throughout the Gangdese belt of southern Tibet. These provide a good opportunity to explore the magmatic process and deep dynamic mechanisms that occurred after collision between the Indo and the Asian plates. In this paper, felsic volcanic rocks from the Zongdangcun Formation in the Wuyu Basin in the central part of the southern Gangdese belt are used to disclose their origin. Zircon U-Pb geochronology analysis shows that the felsic magmatism occurred at ca. 10.3 ± 0.2 Ma, indicating that the Zongdangcun Formation formed during the Miocene. Most of these felsic magmatic rocks plot in the rhyolite area in the TAS diagram. The rhyolite specimens from the Zongdangcun Formation have the characteristics of high SiO2 (>64%), K2O, SiO2, and Sr contents, a low Y content and a high Sr/Y ratio, and the rocks are rich in LREE and depleted in HREE, showing geochemical affinity to adakitic rocks. The rocks have an enriched Sr-Nd isotopic composition (εNd(t) = −6.76 to −6.68, (87Sr/86Sr)i = 0.7082–0.7088), which is similar to the mixed product of the juvenile Lhasa lower continental crust and the ancient Indian crust. The Hf isotopes of zircon define a wide compositional range (εHf(t) = −4.19 to 6.72) with predominant enriched signatures. The Miocene-aged crustal thickness in southern Tibet, calculated on the basis of the Sr/Y and (La/Yb)N ratios was approximately 60–80 km, which is consistent with the thickening of the Qinghai-Tibet Plateau. The origin of Miocene felsic magmatic rocks with high Sr/Y ratios in the middle section of the Gangdese belt likely involved a partial melting of the thickened lower crust, essentially formed by the lower crust of the Lhasa block, with minor contribution from the ancient Indian crust. After comprehensively analyzing the post-collisional high Sr/Y magmatic rocks (33–8 Ma) collected from the southern margin of the Gangdese belt, we propose that the front edge tearing and segmented subduction of the Indian continental slab may be the major factor driving the east-west trending compositional changes of the Miocene adakitic rocks in southern Tibet.

A Geologic Time Scale 1989. W. B. Harland

1991 ◽  
Vol 99 (5) ◽  
pp. 786-786
Author(s):  
John J. Flynn
Keyword(s):  
Time Scale ◽  
Geologic Time ◽  
Geologic Time Scale

The life cycle of large igneous provinces

2021 ◽  
Author(s):  
Benjamin A. Black ◽  
Leif Karlstrom ◽  
Tamsin A. Mather
Keyword(s):  
Life Cycle ◽  
Large Igneous Provinces ◽  
Igneous Provinces

The use of high-resolution stratigraphy and derived lithoclasts to document structural inversion; a case study from the Paleogene, Isle of Wight, U.K.

2021 ◽  
pp. jgs2020-156
Author(s):  
Andy Gale
Keyword(s):  
The West ◽  
North West ◽  
Geologic Time ◽  
Northern Limb ◽  
The North ◽  
Basement Faults ◽  
Structural Inversion ◽  
Geologic Time Scale ◽  
Radiometric Ages

The effects of structural inversion, generated by the Pyrenean Orogeny on the southerly bounding faults of the Hampshire Basin (Needles and Sandown Faults) on Eocene sedimentation in the adjacent regions were studied in outcrops by sedimentary logging, dip records and the identification of lithoclasts reworked from the crests of anticlines generated during inversion. The duration and precise age of hiatuses associated with inversion was identified using bio- and magnetostratigraphy, in comparison with the Geologic Time Scale 2020. The succession on the northern limb of the Sandown Anticline (Whitecliff Bay) includes five hiatuses of varying durations which together formed a progressive unconformity developed during the Lutetian to Priabonian interval (35-47Ma). Syn-inversion deposits thicken southwards towards the southern margin of the Hampshire Basin and are erosionally truncated by unconformities. The effects of each pulse of inversion are recorded by successively shallower dips and the age and nature of clasts reworked from the crest of the Sandown Anticline. Most individual hiatuses are interpreted as minor unconformities developed subsequent to inversion, rather than eustatically-generated sequence boundaries:transgressive surfaces. In contrast, the succession north of the Needles Fault (Alum Bay) does not contain hiatuses of magnitude or internal unconformities. In the north-west of the island, subsidiary anticlinal and synclinal structures developed in response to Eocene inversion events by the reactivation of minor basement faults. The new dates of the Eocene inversion events correspond closely with radiometric ages derived from fracture vein-fill calcites in Dorset, to the west (36-48Ma).

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