Danakil Depression Research Articles

Lava lake surface characterization by thermal imaging: Erta 'Ale volcano (Ethiopia)

Active lava lakes represent the exposed, uppermost part of convecting magma systems and provide windows into the dynamics of magma transport and degassing. Erta 'Ale volcano located within the Danakil Depression in Ethiopia hosts one of the few permanent convecting lava lakes, probably active for a century or more. We report here on the main features of the lava lake surface based on observations from an infrared thermal camera made on 11 November 2006. Efficient magma circulation was reflected in the sustained transport of the surface, which was composed of pronounced incandescent cracks that separated wide plates of cooler crust. These crossed the lake from the upwelling to the downwelling margin with mean speeds ranging between 0.01 and 0.15 m s−1. Hot spots eventually opened in the middle of crust plates and/or along cracks. These produced mild explosive activity lasting commonly between ∼10 and ∼200 s. Apparent temperatures of cracks ranged between ∼700 and 1070°C, and of crust between ∼300 and 500°C. Radiant power output of the lake varied between ∼45 and 76 MW according to the superficial activity and continuous resurfacing of the lake. Time series analysis of the radiant power output data reveals cyclicity with a period of ∼10 min. The combination of visual and thermal observations with apparent mean temperatures and convection rates allows us to interpret these signals as the periodic release of hot overpressured gas bubbles at the lake surface.

Mapping of hydrothermally altered rocks by the EO‐1 Hyperion sensor, Northern Danakil Depression, Eritrea

An EO‐1 Hyperion scene was used to identify and map hydrothermally altered rocks and a Precambrian metamorphic sequence at and around the Alid volcanic dome, at the northern Danakil Depression, Eritrea. Mapping was coupled with laboratory analyses, including reflectance measurements, X‐ray diffraction, and petrographic examination of selected rock samples. Thematic maps were compiled from the dataset, which was carefully pre‐processed to evaluate and to correct interferences in the data. Despite the difficulties, lithological mapping using narrow spectral bands proved possible. A spectral signature attributed to ammonium was detected in the laboratory measurements of hydrothermally altered rocks from Alid. This was expressed as spectral absorption clues in the atmospherically corrected cube, at the known hydrothermally altered areas. The existence of ammonium in hydrothermally altered rocks within the Alid dome has been confirmed by previous studies. Spectral information of endmember's mineralogy found in the area (e.g. dolomite) enables a surface mineral map to be produced that stands in good agreement with the known geology along the overpass. These maps are the first hyperspectral overview of the surface mineralogy in this arid terrain and may be used as a base for future studies of remote areas such as the Danakil.

Early Man and his Culture from Eritrea in Northeast Africa

The track of human evolution and its cultural remnants set evergreen inquiry in the minds of every modern man. African continent has yielded rich evidences that proved crucial not only in establishing the identity of human ancestors but also the cultural evolutionary trends complementing with the biological evolution. The post-independent era of Eritrea with the prevailing peace became conducive to undertake the present geo-archaeological explorations in different environmental zones such as the Eastern Rift and the Danakil Depression, the central highlands and the western and southwestern lowlands. The explorations made in the Buyya region in Eritrea during 2002, provided rich collections of cultural artifacts including stone tools that marks technically improved the workmanship in tool making. A pastoral rock art examined at Adi Keih depicted the human figures with weapons like spears, shields and arrows, and a few hump-less cattle. The evidences obtained in this study suggest that the cultural ecology of various primitive communities of Eritrea existing today such as Kunama, Nara, Rashaida, Afar, Saho, Bilen, Hidareb, Tigre and Tigrinya can be understandable from the varied cultural paradigms developed over a period of time in response to the then prevailed local environment. Thus, this study adds more evidences to the understandings of early human colonization in relation to the cultural artifacts.

Early man and his culture from Eritrea in Northeast Africa

The track of human evolution and its cultural remnants set evergreen inquiry in the minds of every modern man. African continent has yielded rich evidences that proved crucial not only in establishing the identity of human ancestors but also the cultural evolutionary trends complementing with the biological evolution. The post-independent era of Eritrea with the prevailing peace became conducive to undertake the present geo-archaeological explorations in different environmental zones such as the Eastern Rift and the Danakil Depression, the central highlands and the western and southwestern lowlands. The explorations made in the Buyya region in Eritrea during 2002, provided rich collections of cultural artifacts including stone tools that marks technically improved the workmanship in tool making. A pastoral rock art examined at Adi Keih depicted the human figures with weapons like spears, shields and arrows, and a few hump-less cattle. The evidences obtained in this study suggest that the cultural ecology of various primitive communities of Eritrea existing today such as Kunama, Nara, Rashaida, Afar, Saho, Bilen, Hidareb, Tigre and Tigrinya can be understandable from the varied cultural paradigms developed over a period of time in response to the then prevailed local environment. Thus, this study adds more evidences to the understandings of early human colonization in relation to the cultural artifacts. Keywords: Eritrea, Early man, Northeast Africa, culture, human evolution, Stone Age, tools, Homo sapiens.

The Red Sea and Gulf of Aden Basins

The Red Sea and Gulf of Aden Basins

THE LATE EARLY PLEISTOCENE HUMAN REMAINS FROM BUIA, DANAKIL DEPRESSION, ERITREA

The Early Pleistocene sedimentary succession of the Dandiero (Buia) Basin (Danakil Depression, Eritrea) has preserved a rich paleontological, paleoanthropological, and archeological record. Fieldwork undertaken between 1995 and 2003 on a site at Uadi Aalad (Abbate et al. 1998) led to the discovery of one-million-year-old human remains. They consist of a cranium in excellent preservation condition (UA-31), two permanent teeth (UA-222 and UA-369), and three pelvic portions (UA-173, UA-405 and UA-466, the latter recovered on 2003). The cranium and the postcranial remains represent a single adult individual, likely of female sex. The cranium evidences a blend of erectus -like and progressive morpho-architectural features, the latter more commonly found in the Middle Pleistocene. Preparation and restoration of the specimens (notably, of the virtually complete UA-31 face) were only completed on September 2003. The revision, refinement, and integration of our previous analytical and interpretative work (cf. Abbate et al. 1998; Macchiarelli et al. 2002) is in progress within the context of the paleoanthropological reord currently available for the African Early to Middle Pleistocene.

TAPHONOMIC ANALYSIS OF THE LATE EARLY PLEISTOCENE BONE REMAINS FROM BUIA (DANDIERO BASIN, DANAKIL DEPRESSION, ERITREA):EVIDENCE FOR LARGE MAMMAL AND REPTILE BUTCHERING

The Early Pleistocene sedimentary succession of the Dandiero (Buia) Basin (Danakil Depression, Eritrea) has preserved a rich paleontological, paleoanthropological, and archeological record circa one million years old. Fieldwork undertaken between 1995 and 2003 led to the collection of fossil vertebrate remains now stored at the National Museum of Eritrea. Bones were recovered in different localities of the Dandiero Basin, where abundant archaeological and paleontological remains outcrop from the eroded sediments. The faunal collection of 436 animal bones from the Buia Basin, mostly derived from Uadi Aalad area, have undergone taphonomic analysis. Even though bone surfaces are poorly preserved due to abrasion, our work demonstrates carcass exploitation. Some specimens, mostly representing Hippopotamus gorgops and medium- to large-sized bovids, show traces of butchering left by stone tools. We also document, as far as we know for the first time, a single case of butchering involving a femur of a crocodile.

FOSSIL REPTILES FROM THE PLEISTOCENE HOMO-BEARING LOCALITY OF BUIA (ERITREA, NORTHERN DANAKIL DEPRESSION)

The early to early-Middle Pleistocene fossil assemblage form the Buia area (Northern Danakil Depression, Eritrea) hosts, along with Homo and several other large mammal taxa, the following reptiles: Nile Crocodile, Crocodylus niloticus , Serrated Hinged Terrapin, Pelusios cf. P. sinuatus, Nile Monitor, Varanus niloticus and African Rock Python , Python gr. sebae . All the identified taxa belong to living species. At present, these taxa do not occur in the Northern Danakil depression since it is an arid area. P. sinuatus is not a member of the Eritrean herpetofauna. Although the marked preponderance of the crocodile remains is probably connected to the taphonomy of the sites and the collecting methods used, the ecological value of the reptile fauna corroborates that of the mammals, in indicating a lacustrine or fluvio-deltaic palaeoenvironment and a tropical/subtropical or even sub-Sahelic climate. The Buia remains represent the first reported Eritrean palaeoherpetofauna.

Large magnitude silicic volcanism in north Afar: the Nabro Volcanic Range and Ma?alalta volcano

Much of the volcanological work carried out in north Afar (Ethiopia and Eritrea) has focused on the nature of Quaternary basaltic volcanic ranges, which have been interpreted by some as incipient oceanic ridges. However, we show here that comparable volumes of silicic magmas have been erupted in the region. In particular, the virtually undocumented Nabro Volcanic Range, which runs NNE for more than 100 km from the margin of the Danakil Depression to the Red Sea coast, has a subaerial volume of the order of 550 km3, comparable to the volume of the much better known Erta’Ale axial volcanic range. Nabro volcano itself forms part of an enigmatic double caldera structure with a neighbouring volcano, Mallahle. The twin caldera may have formed simultaneously with the eruption of between 20 and 100 km3 of ignimbrite, which is readily identified in Landsat Thematic Mapper imagery. This may have been the largest explosive eruption in north Afar, and is certain to have deposited a regionally distributed tephra layer which could in the future be located in distal sections as a stratigraphic marker. An integrated analysis of optical and synthetic aperture radar imagery, digital topographic data, field observations and limited geochemical measurements, permits here descriptions and first order inferences about the structure, stratigraphy and compositions of several major volcanoes of the Afar Triangle, and a reappraisal of their regional significance.

Some features of the 1993 Bada earthquake swarm of southeastern Eritrea

Starting from late April and mainly during May of 1993, a swarm of earthquakes hit the locality of Bada in southeastern Eritrea. Bada is located in the Danakil depression, a triple junction zone where the Red Sea, Gulf of Aden and the East African rifts meet. The largest shock had a magnitude of 5.2. There were no reported damages or casualties. By virtue of its proximity, the Asmara (ASME) seismic station recorded hundreds of the events of the earthquake sequence, and 18 of the largest events were located by the ISC. Rockslides and widespread faulting were observed during a field trip that took place at the time of the swarm. Despite certain limitations in the available data, mainly due to the paucity of seismic stations, it is possible to determine some key features of the swarm including its magnitude, time, and spatial distributions. The b-value of the earthquake swarm is estimated to be 1.67.

Fossil elephants from Buia (Northern Afar Depression, Eritrea) with remarks on the systematics of Elephas recki (Proboscidea, Elephantidae)

ABSTRACT A succession of five fossiliferous levels near Buia in the northern Danakil (Afar) Depression of Eritrea has produced an abundant early Pleistocene fauna including a ca. 1.0 Ma cranium of Homo. Elephas is well represented at many sites; with one exception the entire Buia Elephas sample represents a relatively derived member of the Elephas recki lineage. Univariate and multivariate analysis of dental characters demonstrates that the Buia sample is intermediate between E. recki ileretensis (Koobi Fora, Ileret) and E. r. recki (Beds 3 and 4 at Olduvai). The biologic reality of the separation of E. recki into five chronologically successive subspecies is questionable. Our analysis supports the hypothesis that E. r. ileretensis and E. r. recki form a single phyletic lineage.

Toward an optimised laser cleaning procedure to treat important palaeontological specimens

In previous laser cleaning tests and analyses carried out on fossil bones, we demonstrated the feasibility and effectiveness of the laser approach. Based on these results, we designed a cleaning procedure employing fibre-optic-delivered Nd:YAG laser radiation, integrated with other conventional cleaning techniques, such as micro-sandblasting and chemical cleaning. The procedure has been optimised for application on important specimens, such as the fossil human “skull of Buia”, recently discovered by a research expedition of the Department of Earth Sciences of the University of Florence and presently preserved in the Museum of Asmara (Eritrea). Here, we report laser cleaning tests where this procedure has been applied on samples of other mammalian bones from the Danakil depression and the site of Matassino (Italy).

Field temperature measurements at Erta'Ale Lava Lake, Ethiopia

The shield volcano Erta'Ale, situated in the Danakil Depression, Ethiopia, is known for its active lava lake. In February 2001, our team visited this lake, located inside an 80-m-deep pit, to perform field temperature measurements. The distribution and variation of temperature inside the lake were obtained on the basis of infrared radiation measurements performed from the rim of the pit and from the lake shores. The crust temperature was also determined from the lake shores with a thermocouple to calibrate the pyrometer. We estimated an emissivity of the basalt of 0.74 from this experiment. Through the application of the Stefan-Boltzmann law, we then obtained an estimate of the total radiative heat flux, constrained by pyrometer measurements of the pit, and visual observations of the lake activity. Taking into account the atmospheric convective heat flux, the convected magma mass flux needed to balance the energy budget was subsequently derived and found to represent between 510 and 580 kg s–1. The surface circulation of this mass flux was also analyzed through motion processing techniques applied to video images of the lake. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00445-002-0224-3.

Ground deformation near Gada ‘Ale Volcano, Afar, observed by radar interferometry

Radar interferometric measurements of ground‐surface displacement using ERS data show a change in radar range, corresponding to up to 12 cm of subsidence near Gada ‘Ale volcano in northern Afar, Ethiopia, that occurred between June 1993 and May 1996. This is the area of lowest topography within the Danakil Depression (−126 m). Geodetic inverse modeling and geological evidence suggest a volcanic origin of the observed deformation; it was probably caused by a combined process of magma withdrawal from a larger reservoir and normal faulting. There is no evidence of subaerial eruption. This is the only identifiable deformation event during June 1993–October 1997 in the 80 km long Erta ‘Ale volcanic range, indicating surprising inactivity elsewhere in the range.

A geochemical reconnaissance of the Alid volcaniccenter and geothermal system, Danakil depression, Eritrea

Geological and geochemical studies indicate that a high-temperature geothermalsystem underlies the Alid volcanic center in the northern Danakil depression of Eritrea Alid is avery late-Pleistocene structural dome formed by shallow intrusion of rhyolitic magma some of which vented as lavas and pyroclastic flows Fumaroles and boiling pools distributed widelyover an area of ∼10 km2 on the northern half of Alid suggest that an activehydrothermal system underlies much of that part of the mountain Geothermometers indicate thatthe fumarolic gases are derived from a geothermal system with temperatures >225°C Theisotopic composition of condensed fumarolic steam is consistent with these temperatures andimplies that the source water is derived primarily from either lowland meteoric waters or fossilRed Sea water or both Some gases vented from the system (CO2 H2Sand He) are largely magmatic in origin Permeability beneath the volcanic center may be high given the amount of intrusion-related deformation and the active normal faulting within theDanakil depression

A one-million-year-old Homo cranium from the Danakil (Afar) Depression of Eritrea.

One of the most contentious topics in the study of human evolution is that of the time, place and mode of origin of Homo sapiens. The discovery in the Northern Danakil (Afar) Depression, Eritrea, of a well-preserved Homo cranium with a mixture of characters typical of H. erectus and H. sapiens contributes significantly to this debate. The cranium was found in a succession of fluvio-deltaic and lacustrine deposits and is associated with a rich mammalian fauna of early to early-middle Pleistocene age. A magnetostratigraphic survey indicates two reversed and two normal magnetozones. The layer in which the cranium was found is near the top of the lower normal magnetozone, which is identified as the Jaramillo subchron. Consequently, the human remains can be dated at approximately 1 million years before present.

Compounding in Qafar

The language described in this chapter is spoken by at least three million people who call themselves Qafar, though earlier European writers and travelers usually referred to them as Danakil. The Qafar inhabit that vast tract of land which stretches from the Red Sea coast south and west as far as the scarplands of the Ethiopian Plateau, an area generally referred to as the Danakil Depression. With the exception of narrow belts of luxuriant jungle along the banks of rivers, such as the Awash and the Mille, which descend into the Depression, the country is largely desert; though even quite short spells of rain can bring grass and other transient plant life back into some parts. Although Qafar living in large coastal towns such as Djibouti and Assab and those on the Red Sea coast who live by fishing have clearly abandoned past oralism as a way of life, the majority of Qafar remain pastoralists, and pastoralism is strongly reflected in the lexicon of their language.

Upwelling asthenosphere beneath western Arabia and its regional implications

Two distinct phases of continental magmatism are evident in western Arabia. The first, from about 30 to 20 Ma, produced tholeiitic‐to‐transitional lavas emplaced along NW trends. The second, from about 12 Ma to Recent, produced transitional‐to‐strongly‐alkalic lavas emplaced along N‐S trends. The older phase is attributed to passive‐mantle upwelling during extension of the Red Sea Basin, whereas the younger phase is attributed to active‐mantle upwelling but was facilitated by minor continental extension perpendicular to plate collision. The younger magmatic phase is largely contemporaneous with a major period of crustal uplift to produce the West Arabian Swell after about 14 Ma. A variety of evidence suggests that the West Arabian Swell is thermally supported by hot, upwelling asthenosphere. In contrast to the distinct asymmetry of uplift and magmatism on opposing sides of the Red Sea Basin, these processes were symmetric across a N‐S line marking the central axis of the West Arabian Swell. This axis coincides with two fundamental features: the Ha'il‐Rutbah Arch in the north, and the Makkah‐Madinah‐Nafud (MMN) volcanic line in the south. The symmetry of magmatism is demonstrated by petrochemical evidence that the MMN harrats were derived by greater degrees of partial melting, at shallower depths, than those harrats lying to the west and east of the MMN line. The potential temperature of the asthenosphere is estimated to be about 1436°C beneath the MMN line and about 1354°C beneath the flanking, more undersaturated harrats. The source of upwelling is either a mantle plume centrally located beneath the West Arabian Swell or an elongated and extended lobe of hot asthenosphere emanating from the Ethiopian mantle plume. Convective flow may have been channelled along a preexisting, regional flexure in the continental lithosphere which concentrated hot asthenosphere beneath the central axis of the AfroArabian Dome. This crest of mantle upwelling underlies the MMN line in the north and the Danakil Depression and Ethiopian rift system in the south. It also passes through the Red Sea Basin at the midpoint of an unusual, doubly propagating rift system where axial seafloor spreading began 4–5 m.y. ago. The NW trend of the Red Sea Basin was well established by crustal attenuation during the older magmatic phase. The Pliocene invasion of this basin by a N‐S zone of mantle upwelling has resulted in seafloor spreading parallel to the preexisting structure along a rift system that has continued to propagate away from its eccentric mantle source in two opposing directions.

Characteristics of the Bab Al Mandab-Northern Afar Area of the Southern Red Sea

The southern Red Sea and adjacent Afar area represent an enigmatic portion of the Red Sea/Gulf of Aden basin system. Although the topographic rift shoulders of the Red Sea and Gulf of Aden can be traced through this elbow, and appear to suggest that a similar width for the zone of extension is maintained across the region, the character of the floor of the rift zone changes. The distinctive character of the southern Red Sea-Afar area results in part from a topographically elevated region, possibly associated with the Red Sea-Gulf of Aden-East African rift triple junction. In addition, however, seismic data from offshore Ethiopia suggests that the distinctive character is due a complex pattern of rifting. The central axial trough of the Red Sea decreases in depth to the south toward the strait of Bab al Mandab, suggesting that rifting is dying out southward. Farther to the west at the same latitude, a major but narrow half-graben can be seen on seismic in the Gulf of Zula, bounded to the east by a large west-dipping normal fault. This structure continues south into the Danakil Depression of the Afar area. Between these two en echelon rift trends, the Danakil Alps formmore » a long-lived high. Seismic data from the southern Red Sea of Ethiopia show southward thinning and pinch-out of the Miocene syn-rift evaporite sequence onto the northern Danakil block. Thus, it appears that the Danakil block has largely escaped Red Sea extension and subsidence. Instead, it forms a large unextended terrain located between overlapping en echelon rift trends, and may represent an accommodation zone structure associated with offset in the rift axis of the southern Red Sea.« less

A comparative study of the sedimentary fills of the Danakil Depression (Ethiopia) and Dead-Sea Rift (Israel)

A great similarity exists between the sedimentary fill of the Danakil Depression and that of the Dead Sea. Both record the history of two tectonic pulses, which formed the Syro-African rift.