taru-adjective, adverb taking the 'to' particle
Formal or literary term describing things that are varied, not uniform, or split into many parts. Often used in the adverbial form 区区として or 区区に.
意見が区区に分かれた。
Opinions were divided into various camps.
参加者の背景は区区だ。
The backgrounds of the participants are diverse.
taru-adjective, adverb taking the 'to' particle
Formal or literary term for matters that are small-minded, trifling, or not worth serious attention. Often used in the adverbial form 区区として or 区区たる.
区区たる問題にこだわるな。
Don't get hung up on trivial matters.
彼は区区たる利益のために争った。
He fought over a petty profit.
些細 is the standard word for 'trivial' or 'minor'; 区区 in this sense is more literary and can carry a nuance of being fragmented or petty.
Reduplication of 区 (ku, 'ward, district, division'), emphasizing division or separation. The exact historical derivation is uncertain, but the meaning 'various' likely developed from the idea of things being split into many parts.