The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251○ ≤l ≤ 358○ and 2○ ≤l ≤ 61○ at |b| ≤ 1 5). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8″ and a broadband RMS sensitivity of ∼10–20 μJy beam−1. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908–1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE H II region candidates are not true H II regions; and a large sample of previously undiscovered background H I galaxies in the Zone of Avoidance

The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

Thrust-related dome structures in the Karibib district and the origin of orthogonal fabric domains in the south Central Zone of the Pan-African Damara belt, Namibia

The high-grade metamorphic south Central Zone (sCZ) exposes an oblique crustal section through the internal parts of the Pan-African Damara belt in Namibia. The structural pattern of the south Central Zone is characterized by kilometer-scale, northeast-trending dome structures for which a number of different origins have been proposed. Detailed structural mapping of the Karibib and Usakos domes in the Karibib district indicates an origin of the two domes as large tip-line folds located above blind thrusts. The two domes are overridden from the southeast by a crystalline thrust sheet along the Mon Repos thrust zone and the thrusts and associated folds form part of a deeply-eroded, foreland- (northwest-) vergent fold-and-thrust belt. Intrusive relationships of syn- and post-tectonic granitoids constrain the timing of thrusting to between 550 and 540 Ma, corresponding to the main phase of collisional tectonics in the Damara belt. On a regional scale, the south Central Zone is underlain by two orthogonal fabric domains. Northwest-vergent tectonic transport, documented in this study, dominates the lower amphibolite-facies northeastern parts of the south Central Zone. In contrast, a southwest-directed orogen-parallel extrusion is widely documented for the lower structural levels of the upper-amphibolite- to granulite-facies southwestern parts of the south Central Zone that contain voluminous synkinematic granites and widespread migmatization. Fabric development in the two orthogonal domains can be shown to be contemporaneous and related to the main collision between the Congo and Kalahari cratons at ca. 540-550 Ma. We suggest that the formation of the two orthogonal fabric domains represents the different crustal response of the rheologically layered crust to the late-Proterozoic crustal shortening. At shallower crustal levels, shortening of sufficiently strong crust in the Karibib district resulted in vertical thickening and orogen-normal folding and thrust transport. Shortening of the deeper levels of the sCZ resulted in pure shear deformation of the rheologically weakened and partially molten crust and the lateral, orogen-parallel displacement of rocks. © 2004 Elsevier B.V. All rights reserved.Articl

Timing and kinematics of the Colenso Fault: The Early Paleozoic shift from collisional to extensional tectonics in the Pan-African Saldania Belt, South Africa

The Colenso fault is a major northwest to southeast trending fault zone in the Pan-African Saldania Belt of the Western Cape Province in South Africa that is spatially closely associated with granitoids of the ∼550 to 510 Ma Cape Granite Suite. Most of these granites were previously considered to be largely post-tectonic intrusions, but structural data presented in this study demonstrate the synkinematic emplacement of granitoids into, and along, the Colenso Fault. The kinematic analyses of shear zones and granite fabrics together with previously published and new geochronological data are combined to provide constraints on the complex kinematic history of the fault and the tectonic evolution of the hitherto poorly understood Saldania Belt. Early, strongly gneissose granitoids of the composite Darling batholith (547 ± 6 Ma) were emplaced during sinistral strike-slip movement along the Colenso fault. Both the timing of emplacement and penetrative deformation of the Darling batholith suggest an intrusion of the pluton during the main Pan-African collisional event in the Saldania Belt. The younger Trekoskraal granite intrudes synkinematically into dextral strike-slip faults related to deformation along the Colenso fault. Single-zircon ages from synkinematic aplites constrain the timing of dextral strike-slip shearing to 539 ± 4 Ma. The emplacement of the late-kinematic Cape Columbine granite during dextral strike-slip faulting indicates that dextral strike-slip kinematics along the Colenso fault continued at least until ∼520 Ma. These results point to a reversal of strike-slip motion along the Colenso fault at ∼540 Ma that coincides with the onset of uplift of rocks of the Saldania Belt. The final exhumation of the belt at ∼515 to 520 Ma is marked by the near-surface emplacement of the last phases of the Cape Granite Suite, related subaerial volcanism, sedimentation of the coarse-clastic, fault-bounded Klipheuwel Group, and the overlying fluvial to shallow-marine sequence of the Mid-Cambrian Cape Supergroup. The temporal and spatial overlap between igneous activity and rift-type sedimentation indicates that a substantial part of the Cape Granite Suite was emplaced in an overall transtensional and/or extensional setting. During this time, the voluminous plutonism of the Cape Granite Suite most likely represented a significant heat input that also contributed to a thermal weakening of the crust. In view of the Early Paleozoic extensional setting suggested here, we interpret Ar-Ar mineral ages of ∼500 Ma and post-orogenic plutonism that are widely documented from Pan-African belts throughout southwestern Africa to reflect a thermal event related to crustal thinning and associated mantle upwelling that follows the main phase of Pan-African collisional tectonics.Articl