Geologic map of the south central Rub Al Khali quadrangle, Kingdom of Saudi Arabia

Abstract Harrat Rahat, one of several large, basalt-dominated volcanic fields in western Saudi Arabia, is a prime example of continental, intraplate volcanism. Excellent exposure makes this an outstanding site to investigate changing volcanic flux and composition through time. We present 93 40Ar/39Ar ages and six 36Cl surface-exposure ages for volcanic deposits throughout northern Harrat Rahat that, when integrated with a new geologic map, define 12 eruptive stages. Exposed volcanic deposits in the study area erupted <1.2 Ma, and 214 of 234 eruptions occurred <570 ka. Two eruptions occurred in the Holocene, including a historically described basalt eruption in 1256 C.E. and a trachyte eruption newly recognized as Holocene (4.2 ± 5.2 ka). An estimated ∼82 km3 (dense rock equivalent) of volcanic product have erupted since 1.2 Ma, though this is a lower limit due to concealment of deposits >570 ka. Over the past 570 k.y., the average eruption rate was 0.14 km3/k.y., but volcanism was episodic with periods alternating between low (0.04–0.06 km3/k.y.) and high (0.1–0.3 km3/k.y.) effusion rates. Before 180 ka, eruptions vented from the volcanic field’s dominant eastern vent axis and from a subsidiary, diffuse, western vent axis. After 180 ka, volcanism focused along the eastern vent axis, and the composition of volcanism varied systematically along its length from basalt dominated in the north to trachyte dominated in the south. We hypothesize that these compositional variations <180 ka reflect the growth of a mafic intrusive complex beneath the southern portion of the vent axis, which led to the development of evolved magmas.

Download Full-text

Multidrug-ResistantAcinetobacter baumannii: An Emerging Health Threat in Aseer Region, Kingdom of Saudi Arabia

Canadian Journal of Infectious Diseases and Medical Microbiology ◽

10.1155/2018/9182747 ◽

2018 ◽

Vol 2018 ◽

pp. 1-4 ◽

Cited By ~ 7

Author(s):

Mohammed K. Almaghrabi ◽

Martin R. P. Joseph ◽

Mohammed M. Assiry ◽

Mohamed E. Hamid

Keyword(s):

Saudi Arabia ◽

Health Problem ◽

Antibiotic Susceptibility ◽

Multidrug Resistant ◽

High Rate ◽

The South ◽

Kingdom Of Saudi Arabia ◽

Bench Tests ◽

Important Health ◽

Resistant Strains

Objective. The study aims to determine the prevalence of multidrug-resistantA. baumanniiin Aseer Region, Kingdom of Saudi Arabia.Methods. This study evaluated the antibiotic susceptibility of ninety-four (n = 94) clinical isolates ofA. baumannii. The isolates were collected from the south region of Saudi Arabia, and notably Aseer Region, during the period from 15 October 2014 to 15 January 2015. The isolates were tentatively identified asA. baumanniiby routine bench tests and were confirmed by using VITEK® 2 Compact. The latest instrument was used to identify antibiotic susceptibility of these isolates.Results. Antibiotic susceptibility in this study showed that 69% of these isolates were multidrug-resistant strains. Moreover, they were highly resistant to carbapenem drugs. Several strains of these isolates were found to be extremely resistant to test antibiotics and were only sensitive to one or two of them.Conclusion. High rate of multidrug-resistantA. baumanniibacteraemia has emerged in the south region of Saudi Arabia as an important health problem. Therefore, it is considered as a new threat in hospitals, which requires a tremendous effort to stop its escalation and spread.

Download Full-text