It is a point of caution that I want to raise here. One should not expect the sign of his anomaly to be in agreement with the distribution of the sedimentary cover. The sign of the anomaly dependent on your reference datum (regional component) as well as (in part) on the accuracy of various corrections. The density value used in Bouguer correction can be a significant source of errors. Are there wells or other information relevant to estimating thickness of sedimentary cover below the datum to which readings were reduced? Modeling might provide some insight into the matter.

thank you Dr. Abdelmoneam Raef,

I understand that the anomaly is not linked to the sedimentary cover, but I mentioned it so as to give the researchers an idea that the causing body do not cropping out at the surface, instead it may be deep seated. concerning the errors, I have to tell that this anomaly appeared in many gravity surveys conducted by different oil companies and individuals and even from satellite gravity. thanks again.

Based on my theory those kinds of anomalies could be caused by some local formation which causes denser magma flow existence in that area.

Thanks Kimmo Rouvario for your answer,

but I am still asking what type of magma could cause this positive anomaly?

regards

If your positive gravimetric anomaly is not linked to sedimentary cover, it may be caused by a magmatic intrusion.

Have you tried to use magnetic data ?

According to Ram Babu(2003), If the modelled body is dense and magnetic and is caused by the same source, it indicates probably the presence at depth of an igneous magmatic intrusion.

Best regards

@Khalid Apparently notification system here has its own will :-) I got a notification after Djamel's comment!

I can't answer your question about the type of magma. Generally speaking any kind of magma in deep down can cause the phenomenon, it's more related to the formation of layer containing magma.

Thanks Djamel Boubaya and Kimmo Rouvari