Figure 1 - uploaded by Esam O. Abdulsamad
Content may be subject to copyright.
Source publication
Quite thick succession of shallow water and continental sediments mostly of the Meso-Cenozoic age cover large parts of Murzuq basin of southwestern Libya. The majority of beds slope gently from North to South and the outcropping bedrock units belong to two sequences whose contacts are unconformable everywhere. The lower sequence is represented by J...
Contexts in source publication
Context 1
... Murzuq basin covers a large area of southwest Libya and is located between three well-known major tectonic elements, namely, Al Qarqaf high in the north and the Tibisti-Al Harūj and Hoggar uplifts, on its western and eastern borders, respectively (Fig. 1). A major part of Murzuq basin is covered with recent wind blown sands which complete rock exposures are extremely few and far apart. The metamorphic basement, which is exposed as a few patches northern of Brak Village, lies also at a depth of 1485 m below Sabha City and 2985 m in borehole A1-NC34 (near the town of Al Qatrun in the ...
Context 2
... mainly represented by continental sediments and limestones deposited in brackish or restricted environment. The study area which contains different raw materials in different localities is situated broadly in the central and southeastern part of the Murzuq basin. It lies between latitudes 25° 45′ and 26° 45′N and longitudes 12° 00′ and 16° 30′E (Fig. 1). These raw materials are belonging to three main rock units, namely, the Mesák, the Bin Ghanimah and Al-Mahrúqah formations. An additional and important raw material sources are represented by the old and recent continental deposits which consist chiefly of calcareous sandstones, and fined-grained homogenous sands. These continental ...
Similar publications
This article presents the results of an integrated interpretation of measurements made using Audio-Magnetotellurics and Seismic Reflection geophysical methods. The obtained results were used to build an integrated geophysical model of shallow subsurface cover consisting of Cenozoic deposits, which then formed the basis for a detailed lithological a...
Steamboat Rock is a large monolith located in the center of the Grand Coulee in north central Washington (cover, Fig. 1). The rock is triangular in shape, 2.1 mi (3.3 km) long and 0.75 mi (1.2 km) wide. At 2,312 ft (628 m) elevation, it stands 898 ft (274 m) above Banks Lake, a reservoir that currently occupies the floor of the northern portion of...
The repeated opening and closure of oceans along the same trends has long supported the concept, known as the Wilson cycle, of periodical recurrence in orogenic events, and a certain repetitivity in mountain building processes is recognised in the geological record worldwide. Orogenic cycles may be viewed as comprising two extensional stages that a...
SW Iran and the adjacent offshore are prolific petroleum‐producing areas with very large proven oil and gas reserves and the potential for significant new discoveries. Most of the oil and gas so far discovered is present in carbonate reservoir rocks in the Dehram, Khami and Bangestan Groups and the Asmari Formation, with smaller volumes in the Dash...
In the area of Kraków, mineral waters occur mainly in Jurassic limestones, Cretaceous marls and Paleogene and Neogene sands, which are covered by impermeable Miocene clays. Majority of these waters were recharged at the end of the last glacial, and the con-tents of chlorides are in the range of 70–750 mg/L. The water outflowing from a limestone hor...
Citations
... The same units have been given different names in different geological maps, ranging from the Al Mahruqah 'formation' in the Al Fuqaha, Al Haruj al Abyad and Sabha maps (Koráb, 1984;Seidl and Röhlich, 1984;Woller, 1984) to 'continental deposits' in the Awbari and Hamādat Tanghirt maps (Roncevic, 1984;Berendeyev, 1985;Gundobin, 1985;Grubic et al., 1991), to both these units on the Tmassah and Idri geological maps (Koráb, 1984;Parizek et al., 1984). Thirdly, originally Seidl and Röhlich (1984), and later Domaci et al. (1991) andEl Ebaidi andAbdulsamad (2005) applied the Al Mahruqah 'formation' to the carbonate unit (termed the Brak Formation here) exposed on the north side of Wadi ash Shati, when in fact the major thickness of these post-Oligocene sediments in Wadi ash Shati are clastic deposits, with minor carbonates. Finally, Thiedig et al. (2000) expanded the Al Mahruqah 'formation' to include all the 'Pleistocene' to Holocene carbonate units, whereas our work shows some of these units are much older than Pleistocene, and range into the Miocene, as inferred by earlier mapping (Collomb, 1962;Goudarzi, 1970). ...
... The same units have been given different names in different geological maps, ranging from the Al Mahruqah 'formation' in the Al Fuqaha, Al Haruj al Abyad and Sabha maps (Koráb, 1984;Seidl and Röhlich, 1984;Woller, 1984) to 'continental deposits' in the Awbari and Hamādat Tanghirt maps (Roncevic, 1984;Berendeyev, 1985;Gundobin, 1985;Grubic et al., 1991), to both these units on the Tmassah and Idri geological maps (Koráb, 1984;Parizek et al., 1984). Thirdly, originally Seidl and Röhlich (1984), and later Domaci et al. (1991) andEl Ebaidi andAbdulsamad (2005) applied the Al Mahruqah 'formation' to the carbonate unit (termed the Brak Formation here) exposed on the north side of Wadi ash Shati, when in fact the major thickness of these post-Oligocene sediments in Wadi ash Shati are clastic deposits, with minor carbonates. Finally, Thiedig et al. (2000) expanded the Al Mahruqah 'formation' to include all the 'Pleistocene' to Holocene carbonate units, whereas our work shows some of these units are much older than Pleistocene, and range into the Miocene, as inferred by earlier mapping (Collomb, 1962;Goudarzi, 1970). ...
Terrestrial and lacustrine Neogene and Quaternary sediments in the Libyan Fezzan provide key evidence for
paleoclimate changes in the central Sahara, associated with Lake Megafezzan. Understanding of Holocene and
late Pleistocene deposits is resolved, but the age of older sediments is not. We provide the first high-resolution
chronology and stratigraphy of the Neogene deposits in the Fezzan Basin, and so also the central Sahara. The sediments
are divided into three unconformity-bounded units, the oldest unit, comprising the Shabirinah and Brak
formations, is dated usingmagnetostratigraphy. The Shabirinah Formation is a succession of lacustrine and fluvial
units, locallywith humid and arid paleosols, which progressively show evidence of increasing aridity up through
the succession. The overlying Brak Formation is a pedogenically modified palustrine limestone at basin margin
locations. All these units are dated to the early Aquitanian to late Serravallian in the early to mid-Miocene, having
formed prior to major volcanic fields to the east. During the mid-late Aquitanian widespread stromatolitic lake
sediments developed in SE Fezzan. In the late Burdigalian palustrine carbonate units developed that typically
pass laterally into mixed clastic-paleosol-carbonate units that characterise basin margin situations. The
Serravallian-aged Brak Formation is a highstand deposit developed during maximum lake extent, which formed
due to restriction of basin drainage to the north and east, due to growth of the Jabal as Sawda volcanic centre and
uplift of the SW shoulder of the Sirte Basin. Gradual aridification of the central Sahara occurred from the early
Miocene, but this trend was periodically interrupted by humid phases during which Lake Megafezzan developed.
The hyperaridity of the central Sahara must have developed after 11 Ma and the main drainage networks from
the Fezzan Basin were established before 23 Ma, in the Oligocene indicating the great antiquity of major central
Saharan river basins.
... The same units have been given different names in different geological maps, ranging from the Al Mahruqah 'formation' in the Al Fuqaha, Al Haruj al Abyad and Sabha maps (Koráb, 1984;Seidl and Röhlich, 1984;Woller, 1984) to 'continental deposits' in the Awbari and Hamādat Tanghirt maps (Roncevic, 1984;Berendeyev, 1985;Gundobin, 1985;Grubic et al., 1991), to both these units on the Tmassah and Idri geological maps (Koráb, 1984;Parizek et al., 1984). Thirdly, originally Seidl and Röhlich (1984), and later Domaci et al. (1991) andEl Ebaidi andAbdulsamad (2005) applied the Al Mahruqah 'formation' to the carbonate unit (termed the Brak Formation here) exposed on the north side of Wadi ash Shati, when in fact the major thickness of these post-Oligocene sediments in Wadi ash Shati are clastic deposits, with minor carbonates. Finally, Thiedig et al. (2000) expanded the Al Mahruqah 'formation' to include all the 'Pleistocene' to Holocene carbonate units, whereas our work shows some of these units are much older than Pleistocene, and range into the Miocene, as inferred by earlier mapping (Collomb, 1962;Goudarzi, 1970). ...
... The same units have been given different names in different geological maps, ranging from the Al Mahruqah 'formation' in the Al Fuqaha, Al Haruj al Abyad and Sabha maps (Koráb, 1984;Seidl and Röhlich, 1984;Woller, 1984) to 'continental deposits' in the Awbari and Hamādat Tanghirt maps (Roncevic, 1984;Berendeyev, 1985;Gundobin, 1985;Grubic et al., 1991), to both these units on the Tmassah and Idri geological maps (Koráb, 1984;Parizek et al., 1984). Thirdly, originally Seidl and Röhlich (1984), and later Domaci et al. (1991) andEl Ebaidi andAbdulsamad (2005) applied the Al Mahruqah 'formation' to the carbonate unit (termed the Brak Formation here) exposed on the north side of Wadi ash Shati, when in fact the major thickness of these post-Oligocene sediments in Wadi ash Shati are clastic deposits, with minor carbonates. Finally, Thiedig et al. (2000) expanded the Al Mahruqah 'formation' to include all the 'Pleistocene' to Holocene carbonate units, whereas our work shows some of these units are much older than Pleistocene, and range into the Miocene, as inferred by earlier mapping (Collomb, 1962;Goudarzi, 1970). ...
Terrestrial and lacustrine Neogene and Quaternary sediments in the Libyan Fezzan provide key evidence for paleoclimate changes in the central Sahara, associated with Lake Megafezzan. Understanding of Holocene and late Pleistocene deposits is resolved, but the age of older sediments is not. We provide the first high-resolution chronology and stratigraphy of the Neogene deposits in the Fezzan Basin, and so also the central Sahara. The sediments are divided into three unconformity-bounded units, the oldest unit, comprising the Shabirinah and Brak formations, is dated using magnetostratigraphy. The Shabirinah Formation is a succession of lacustrine and fluvial units, locally with humid and arid paleosols, which progressively show evidence of increasing aridity up through the succession. The overlying Brak Formation is a pedogenically modified palustrine limestone at basin margin locations. All these units are dated to the early Aquitanian to late Serravallian in the early to mid-Miocene, having formed prior to major volcanic fields to the east. During the mid-late Aquitanian widespread stromatolitic lake sediments developed in SE Fezzan. In the late Burdigalian palustrine carbonate units developed that typically pass laterally into mixed clastic-paleosol-carbonate units that characterise basin margin situations. The Serravallian-aged Brak Formation is a highstand deposit developed during maximum lake extent, which formed due to restriction of basin drainage to the north and east, due to growth of the Jabal as Sawda volcanic centre and uplift of the SW shoulder of the Sirte Basin. Gradual aridification of the central Sahara occurred from the early Miocene, but this trend was periodically interrupted by humid phases during which Lake Megafezzan developed. The hyperaridity of the central Sahara must have developed after 11 Ma and the main drainage networks from the Fezzan Basin were established before 23 Ma, in the Oligocene indicating the great antiquity of major central Saharan river basins.
