"spanning approximately" is correct and usable in written English.
You can use it to refer to a certain amount of space or time that is not precisely defined. For example: "The Great Wall of China is an impressive feat of engineering, spanning approximately 6,000 km."
The information housed in the Citizens Police Data Project comes primarily from three datasets provided by the Chicago police department, spanning approximately 2002 to 2008 and 2011 to 2015.
The older eon, spanning approximately four billion years of Precambrian time (and sometimes referred to as the Cryptozoic Eon), began with Earth's formation some 4.6 billion years ago.
The keyframes are linked to an animation timeline for avian evolution spanning approximately 105 million years.
An examination of syllabi revisions spanning approximately three decades highlights the frustration experienced by the SMA committee.
The TH-derived paleomagnetic data possibly indicate variation of the geomagnetic field spanning approximately from 20.5 to 17.4 cal.
This dataset consists of 22 sequences captured in urban, suburban, rural, and highway scenarios spanning approximately 35 km.
The temperature profile is retrieved from two 15-μm and one 4.3-μm CO2 radiometer channel measurements in the tangent height range spanning approximately 20 to 120 km.
The minimum tiling paths of contigs I, II, and III are 15, 4, and 4 BAC clones, spanning approximately 1900, 400, and 300 kb, respectively.
The PubChem inactive data set includes more than 194 million protein ligand pairs spanning approximately 648,000 distinct compound structures (Additional file 1: Table S3).
The Advanced Microwave Sounding Unit (AMSU), first launched in 1998, provides measurements in 20 noncontiguous spectral bands spanning approximately 23 to 190 GHz.
The excitation power dependence of the PL spectra was investigated using the variation of the power density of the excitation laser spanning approximately 100 300 W/cm2.
