Possible Remnants of a Meteoroid in Lakshmi Region (possible Natural Colors; credits: Dr Paolo C. Fienga - Lunexit Team)

This full resolution mosaiced image covers an area of approx. 100 by 120 Km (such as about 62 by 74 miles) and is located in the Lakshmi Region of Venus, at 47° North Latitude and 334° East Longitude.

Due to the dense Venusian Atmosphere, Primary Impact Craters of less than a 3 Km (a little less than 2 miles) diameter are nonexistent.
The dark circular region and associated central bright feature in this image are thought to be the remnants of a Meteoroid smaller than the size necessary to create an Impact Crater, and entering the Atmosphere at low velocity (approx. 350 meters/second.)
The central bright feature appears to be a cluster of small secondary impacts, ejecta and debris from the original meteor that broke up in the Atmosphere.

Even though most of the meteorite did not hit the Surface, the Atmospheric Shock wave could be great enough to modify the surrounding region. One explanation for this radar dark circular formation, called "Dark Margins", could be that the shock wave was energetic enough to pulverize the Surface (smooth surfaces generally appear radar dark).
Another explanation is that the Surface could be blanketed by a fine material that was formed by the original meteor's breakup through the Atmosphere.

More than half of the Impact Craters on Venus have associated Dark Margins, and most of these are prominently located left of center of the rater. This is another effect which could be caused by the extremely dense Atmosphere of Venus.