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 كتل الأرض العملاقة - سوبربلوم - المحيّرة infographic
Graphic explains the Earth-Theia collision hypothesis.


كتل الأرض العملاقة - سوبربلوم - المحيّرة

By Ninian Carter

November 2, 2023 - يقول نظريون إن كتلتان ضخمتان وغامضتان مدفونتان في أعماق الأرض هي بقايا كوكب ثيا، الذي يعتقدون هم أنه اصطدم بالأرض قبل 4.5 مليارات سنة، مما أدى إلى تكوّن القمر.

In the 1970s, seismologists discovered two mysterious continent-sized blobs deep inside Earth’s mantle – one under Africa and the other under the Pacific Ocean.

Both blobs, known as Large Low-Shear-Velocity Provinces (LLVPs) or “superplumes”, are denser than the mantle around them and are the biggest deviations in Earth’s simple layered structure.

Researchers hypothesise they are the result of a cataclysmic event early in Earth’s history – known as the “giant-impact hypothesis”.

This theory states that a Mars-sized planet, dubbed Theia, crashed into the Earth 4.46 billion years ago, blasting molten rock into Earth’s orbit – which in time coalesced into our moon.

Researchers ran computer simulations of what may have happened, leading them to wonder if most of Theia was absorbed into Earth, forming the two LLVPs, some 3,000 kilometres below the crust, while residual debris formed the moon.

The increased density of the superplumes is believed to be because of their high levels of iron – similar to moon rocks, which makes sense if the moon is also made from remnants of Theia.

PUBLISHED: 03/11/2023; STORY: Graphic News