Nimba County Research Articles

LIBERIA 1989–1994 A STUDY OF ETHNIC AND SPIRITUAL VIOLENCE

Journal Article LIBERIA 1989–1994 A STUDY OF ETHNIC AND SPIRITUAL VIOLENCE Get access STEPHEN ELLIS STEPHEN ELLIS Researcher Stephen Ellis is a researcher at the Afrikastudiecentrum, Leiden. Search for other works by this author on: Oxford Academic Google Scholar African Affairs, Volume 94, Issue 375, April 1995, Pages 165–197, https://doi.org/10.1093/oxfordjournals.afraf.a098806 Published: 01 April 1995

Liberia

The conflict that broke out in Nimba county, in the north, late in December 1989 slowly spread to the capital during the first half of 1990, leading a growing number of refugees to flee the country. In January, the ICRC set up a delegation in Monrovia to provide assistance within Liberia. The institution also quickly established tracing offices for Liberian refugees in neighbouring Cȏte d'Ivoire and Guinea, and later set up another tracing office in Sierra Leone. The ICRC's regional delegations also provided assistance to the National Societies of the neighbouring countries as they dealt with the influx of refugees.

40Ar/ 39Ar and paleomagnetic results from Liberia and the Precambrian APW data base for the West African Shield

Lower amphibolite to granulite facies metamorphic rocks in Nimba County, Liberia have yielded 2.2–2.9 Ga RbSr whole rock ages, indicating that they are part of the Archean Liberian age province. We report a 2040 Ma 40 40Ar/ 39Ar plateau date on hornblende from an amphibolite in this region, and suggest that these rocks were also severelyreworked during the Eburnean (∼2.0 Ga) metamorphic episode. 40Ar/ 39Ar analyses of biotite and feldspars from neighboring schists also indicate the presence of two mild thermal events, at 1.5 Ga and 0.6 Ga. Paleomagnetic analyses of samples from these same metamorphic rocks reveal three components of magnetization. The predominant and most stable component (273°E, 21°N) is considered to have been acquired as a result of pos Eburnean uplift and cooling at ∼ 2.0 Ga, whereas the two less stable components with poles at 235°E, 43°N and 16°E, 36°N, probably correlate with the 1.5 Ga and 0.6 Ga thermal pulses, respectively. Rock units from southern Liberia also yield two secondary magnetizations, one at 247°E, 37°N and the other at 104°E, 5°N, and a 1.5 Ga 40Ar/ 39Ar date on plagioclase. Comparison of the paleomagnetic poles corresponding to the ∼2.0 Ga Eburnean component with published paleomagnetic data for West Africa is not consistent with prior interpretations of the polar wander path for West Africa. Our paleomagnetic data, when compared to poles of comparable age from the Kalahari Shield, still suggest that some form of displacement has occurred between the Kalahari and West African Shields since 2.0 Ga.

Geology, Geochemistry, and Origin of the Nimba Itabirite and Associated Rocks, Nimba County, Liberia

The upper 700 m of the tightly folded and metamorphosed 1,400-m-thick Precambrian metavolcanic-metasedimentary Nimba Supergroup of northeastern Liberia, West Africa, consists of two pelitic phyllite formations, the Gbahm Ridge and Mt. Alpha Formations, separated by the 350-m-thick Nimba Itabirite. The Nimba Itabirite is metamorphosed to the epidote-amphibolite facies in the northeastern Liberian Nimba range and to upper amphibolite-lower granulite facies in the Tokadeh-Yuelliton ridge. Magnetite oxide-facies iron-formation is recrystallized to gray on northeastern Mt. Nimba. Banded silicate iron-formation comprising other parts of the Nimba range (Mt. Gbahm) and the Tokadeh-Yuelliton ridge is probably recrystallized carbonate-bearing magnetite oxide-facies iron-formation.Chemical balances indicate that iron-formation could have been derived by chemical weathering of the basaltic metavolcanic rocks which are dominant in the lower 700 m of the Nimba Supergroup. The residuum from such weathering would be a siliceous kaolinite, not a laterite, which, when transported to and deposited within a marine basin, would form an argillite. Chemical weathering of the basaltic landmass is believed to have occurred under swampy stagnant kaolin-forming conditions in a climate (either CO 2 -rich or reducing) which encouraged liberation of iron during weathering. Irregularity in thickness and character of banding and poor separation of iron and silica preclude an hypothesis of banding on rhythmic phenomena such as seasonal variation of pH or seasonal overturn of monomictic lakes.So-called blue itabirite forms a 1,300-m-long wedge which envelops the high grade hematitic Main Orebody. It consists of anhedral hematite and quartz and has probably formed by epigenetic alteration of the gray itabirite.