No, these images are not Martian anomalies, they are from right here on Planet Earth.
North Africa, Sahara Dessert, Mauritania. The bizarre feature is known as the Eye of the Sahara.
The eye of the Sahara also known as the Richat Structure or Guelb er Richat, is a highly unusual and bizarre circular formation in the Sahara desert. This structures origins are uncertain, but it dates far into uncharted antiquity.
Its 40 mile wide dome is heavily eroded. It's construction , either by natural phenomena or intelligent design has exposed sedimentary rock from Late Proterozoic era, which is the time immediately preceding the proliferation of complex life on Earth - roughly 2.5 Billion years ago give or take a few hundred Centuries. The interior of the eye of the Sahara contains various igneous and volcanic rocks.
Natural or Man Made Formation
Initially it was believed to have been created by an asteroid impact. It is now believed to be a bizarrely circular symmetrical and deeply eroded geologic dome. There is zero evidence for shock metamorphism which would indicate a meteor impact.
Some believe the structure may have been created by intelligent design, be it Human or an alien intelligence, however the consensus seems to be that it is hydro-thermal alteration, dissolution and collapse of the unique collection of varying rock structure accumulated within the structure over the eons.
"In 1994, Arthus-Bertrand started a thorough study on the state of the Earth sponsored by UNESCO. As part of the study, he made a picture inventory of the world’s most beautiful landscapes, taken from helicopters and hot-air balloons. That work became Earth from Above, which has now been translated into more than two dozen languages. Arthus-Bertrand has continued to travel and photograph the planet, collecting material that has never before been published.
In this updated edition, he reveals more than 100 additional images and presents essays on current environmental and humanitarian issues by esteemed experts, including Nicholas Stern, Jane Goodall, Runa Khan, and Matthieu Ricard.
With thrilling photography, essays, and revisions throughout, this edition of Earth from Above is a portrait of our world that poignantly juxtaposes evidence of humanity’s destructive impact with the planet’s raw beauty." - Earth From Above From amazon.com