Investigators have uncovered how a historical aridity event expedited the shifting of lithospheric plates and triggered magma deep below.
East Africa / © livescience
The shift in East Africa’s weather patterns, evolving from a humid state to a dry one over the last several millennia, has quickened the continent’s crustal fracturing.
This is asserted in a recent analysis featured in the publication Scientific Reports, according to Live Science.
According to these experts, for around the last 5,000 years, East Africa has progressively seen a decline in the moisture-rich weather experienced during what’s known as the African Humid Period. Consequently, levels in expansive lakes, such as Lake Turkana in Kenya, have drastically decreased, which has impacted the condition of the Earth’s outer layer.
The inquiry was spearheaded by Christopher Scholz, a geologist and physicist, and emeritus professor at Columbia University. According to him, the findings evince a reciprocal interaction between weather and geological occurrences.
“Typically, we consider the converse: that mountain building alters weather at a localized or wider scope. Nevertheless, our evidence suggests weather can also directly affect tectonic activity,” Scholz commented.
Site and lab investigations were carried out near Lake Turkana, among the biggest and most profound reservoirs within the East African Rift. Presently, it stretches approximately 250 km in length, measures as wide as 30 km, and reaches depths of 120 meters in places. Contrarily, over 5 millennia ago, its water surface was approximately 150 meters elevated.
During that era, much of Africa was considerably wetter than it is now. The African Humid Period spanned from approximately 9600 to 5300 years in the past, after which drier atmospheric states started becoming prevalent in the area.
Via scrutinizing the substratum deposits of Lake Turkana, researchers have pieced together previous watermarks and sedimentary rock streams. Inside these strata, they detected numerous minor ruptures and markers of age-old seismic events, pointing to a modification in geological dynamics within the vicinity.
The East African Rift represents an area where the African lithospheric plate is gradually distending and could eventually cleave into a pair of discrete plates, giving rise to a new ocean in the intervening space. This occurrence sheds light on the presence of deep and slender lakes across the territory, including Lake Turkana and Lake Malawi.
The investigators resolved to ascertain whether fluctuations in water elevations could tangibly bear on the rate at which plates are drifting apart. Water is pivotal in tectonic processes: for example, thawing ice sheets diminish the burden on the Earth’s mantle, leading it to ascend, a phenomenon recognized as isostatic equilibrium. Correspondingly, sizable quantities of water can exert stress on the mantle and impede fracture activity.
Experts approximate that following the termination of the African Humid Period, fissures within the Lake Turkana area began shifting more rapidly, at an accelerated average pace of 0.17 mm yearly. Comparatively, the comprehensive tempo of African divergence in that area is approximated at roughly 6.35 mm annually.
Computational modeling has illustrated that the intensification of geological activity has dual underlying causes. The primary factor entails a lessened compression on the Earth’s envelope resulting from the discharge of substantial water volumes, thus granting fractures greater latitude to mobilize. The secondary factor is indirect: situated on an islet in Lake Turkana’s southern sector exists a volcano harboring an energized magma reservoir. The alleviation of load engendered decompression within the mantle beneath the volcano, intensified rock melting, and the infusion of magma into the reservoir, which, in turn, augmented pressure on adjacent fractures.
“We are perceiving elevated fissure formation throughout this interval, hence we can deduce that seismic occurrences within the region are transpiring with greater regularity now than, hypothetically, 8,000 years prior,” Scholz remarked.
A crew of scientists is presently occupied with an analogous undertaking at Lake Malawi, scrutinizing water surface oscillations over the last 1.4 million years. Their objective lies in cultivating a superior grasp of how protracted weather variations sway continental displacement.
“Data pertaining to substantial-scale shifts in water capacities within these lakes holds paramount significance for grasping the comprehensive scenario,” the scientist concluded.
A reminder that we have formerly reported on the potential for the Kenyan, Tanzanian, Ethiopian, and Somali territories to evolve into a fresh continent due to a geological fault.
Source: tsn.ua