Search results for " Africa"
showing 10 items of 604 documents
Bio-ecological, phytosociological and conservation aspects of relictual and disjointed populations ofSimethis mattiazzi(Vandelli) Sacc. (Xanthorrhoea…
2012
Abstract Two populations of Simethis mattiazzi (Xanthorrhoeaceae) were recently discovered in the Channel of Sicily – (1) Punta Bassana (Marettimo Island) and (2) Mount S. Giuliano (western Sicily) – at a considerable distance from the nearest stations hitherto known, located in southern Sardinia, the Pontine Islands Archipelago and Tunisia. The taxonomical and distributive aspects of this species are analysed to highlight the relictual and biogeographical significance of the disjointed and fragmentary nuclei distributed in several small islands of the Channel of Sicily, the Italian Peninsula and North Africa. Some morphological, biological, ecological and phytosociological aspects of the t…
Tectonothermal Evolution of the Broadly Rifted Zone, Ethiopian Rift
2019
The Broadly Rifted Zone (BRZ) of southern Ethiopia is a long-lived and structurally complex segment of the East African Rift System. However, due to poor surface exposure of early synrift strata and a dearth of subsurface data, the evolution of the BRZ remains poorly understood. We present new apatite (U-Th-Sm)/He and augmented apatite fission track low-temperature thermochronology data from the Beto and Galana basin boundary fault systems to constrain the tectonothermal evolution of the western and eastern BRZ, respectively. Time-temperature reconstructions suggest that East African Rift System-related extension began concurrently across the BRZ in the early Miocene (20–17 Ma), at least 6 …
Kinematic and sedimentological evolution of the Manyara Rift in northern Tanzania, East Africa
2005
We describe the stratigraphical/sedimentological and structural evolution of the Manyara Rift in the Tanzania Divergence Zone, East Africa. The rift-related Manyara Beds on the shoaling side of the Manyara Rift were deposited between <1.7 and 0.4 Ma and can be separated into a lacustrine lower member and a fluvial upper member. The transition from lacustrine to fluvial sedimentation at ∼ 0.7 Ma appears to be related to a southward shift of major rift faulting. Fault geometry and the kinematics of the faults are consistent with major faulting during NE/E-directed extension. There is also evidence for other extensional directions including radial extension, which might be caused by magmati…
Rift nucleation, rift propagation and the creation of basement micro-plates within active rifts
2008
Abstract In this contribution we study the dynamics of rift nucleation and the interaction of propagating rift segments. We use the East African Rift System (EARS) as a case study with special emphasis on the Albertine rift system situated within the western branch of the EARS with the 5000 m high Rwenzori horst, a basement block that was captured by two rift segments. Fieldwork in the Rwenzori mountains shows that the range is not only affected by range parallel faults but that major fault sets cut across the Rwenzoris. In order to understand these complex fault patterns and the dynamics of the process that leads to the capturing of basement blocks within the extending rift system we devel…
Melt infiltration of the lower lithosphere beneath the Tanzania craton and the Albertine rift inferred from S receiver functions
2012
[1] The transition between the lithosphere and the asthenosphere is subject to numerous contemporary studies as its nature is still poorly understood. The thickest lithosphere is associated with old cratons and platforms and it has been shown that seismic investigations may fail to image the lithosphere-asthenosphere boundary in these areas. Instead, several recent studies have proposed a mid-lithospheric discontinuity of unknown origin existing under several cratons. In this study we investigate the Tanzania craton in East Africa which is enclosed by the eastern and western branches of the East African Rift System. We present evidence from S receiver functions for two consecutive discontin…
Influence of pre-existing fabrics on fault kinematics and rift geometry of interacting segments: Analogue models based on the Albertine Rift (Uganda)…
2011
This study aims at showing how far pre-existing crustal weaknesses left behind by Proterozoic mobile belts, that pass around cratonic Archean shields (Tanzania Craton to the southeast and Congo Craton to the northwest), control the geometry of the Albertine Rift. Focus is laid on the development of the Lake Albert and Lake Edward/George sub-segments and between them the greatly uplifted Rwenzori Mountains, a horst block located within the rift and whose highest peak rises to >5000 m above mean sea level. In particular we study how the southward propagating Lake Albert sub-segment to the north interacts with the northward propagating Lake Edward/George sub-segment south of it, and how this i…
<strong><em>Chilocoris laevicollis</em> Horváth, 1919, and<em> Ch. umbricola</em> Linnavuori, 1993—two trogloxenic burr…
2016
First country records of two burrower bugs, Chilocoris laevicollis , and Ch . umbricola (Hemiptera: Heteroptera: Cydnidae) from Gabon (Central Africa) are presented. The study was based on the specimens collected by Dr. V. Aellen, a well-known Swiss speleologist, taken from two caves near Lastoursville in the Gabonese Republic. Diagnostic characters for both recorded species are provided, and data on their biology and distribution are summarized.
Making conservation sustainable under unfavourable conditions : the case of Chimanimani National Reserve, Mozambique
2019
Based on a case study from the Chimanimani National Reserve in Mozambique, this article analyses to what extent different types of operational practices can contribute to the sustainability of protected areas in relatively unfavourable external conditions. While current conservation policies highlight community participation and market-based approaches, the same “best practices” are not equally valid under different conditions. Where unfavourable natural conditions, lack of infrastructure, difficult access and political instability limit the potential for upmarket ecotourism, actors should focus on community empowerment, diversification of livelihoods, and building joint conservation ideolo…
Synthesis of Lessons Learned. Enhancing Equity in the Relationship between Protected Areas and Local Communities in the Context of Global Change. Hor…
2003
This study is a review of the engagement of local communities in the management of natural resources in the Horn of Africa and Kenya, with the objective to contribute to enhancing equity in the relationship of local communities with protected areas.
Le récit d’esclave africain-américain : réflexions sur une appellation générique
2015
What do we talk about when we talk about 'slave narratives?' African American slave narratives have been a staple of American literary studies over the past decades. The narratives of Frederick Douglass, Harriet Jacobs and other ex-slaves have been recovered, anthologized and discussed by eminent critics such as Marion Wilson Starling, Henry Louis Gates Jr., Frances Smith Foster and William L. Andrews. For all its ubiquity, however, the generic label 'slave narrative' has been used in many different ways by specialists of African American literature. In this essay I argue that the systematic and sometimes uncritical use of the label has led to generalizations that limit our understanding of…