Meaning of 「微細にわたる説明」

Question

I'm looking at the definition of 微細 in different dictionaries. One dictionary gives the example 微細にわたる説明. Does this mean "an explanation that barely gets across," or does it mean something more like 説明は微細な点にまでわたる, which was an example given in another dictionary.

Answer 1

微細 is used as a noun here (rather than the continuative/adverbial form of the na-adjective 微細な) and means "details". 微細にわたる means "go into minute detail". So...

［微細にわたる］説明 = An explanation ［that goes into detail］ (i.e. "A detailed explanation")

Answer 2

微細にわたる説明 from デジタル大辞泉 means an explanation that is so detailed that it reaches the level of 微細 (きわめて細かく小さいこと).

From 大辞林 definition of わたる

⑤ 〔「亘る」とも書く〕 ある範囲に及ぶ。 ㋑ 広い範囲に及ぶ。くまなく及ぶ。 「各分野に－・る広い学識を備えている」 「研究は多岐に－・っている」 「原因を細部に－・って調べる」 「話が私事に－・って恐縮ですが…」

にわたる is being used to indicate the extent of that the explanation reaches.