type Section (lines:string list) =
    member x.Lines = lines

/// Splits a sequence after the last line of a section defined by the predicate.
let splitAtEach (predicate: 'T -> bool) (xs : seq<'T>) : seq<'T list> =
    let section = new ResizeArray<'T>()
    seq {
        for x in xs do
            section.Add x
            if predicate x then 
                yield Seq.toList section
                section.Clear()
        if section.Count > 0 then
            yield Seq.toList section}

/// Splits a sequence before the first line of a section defined by the predicate.
let splitBeforeEach (predicate: 'T -> bool) (xs : seq<'T>) : seq<'T list> =
    let section = new ResizeArray<'T>()
    seq {
        for x in xs do
            if predicate x then 
                yield Seq.toList section
                section.Clear()
            section.Add x
        if section.Count > 0 then
            yield Seq.toList section}

usage:

open System.IO

let lines = File.ReadAllLines(myTextFile)

let getSections lines =
    splitAtEach isSectionLine lines
    |> Seq.map (fun x -> new Section(x))
    |> Seq.toList

This is a slightly modified version from: https://codereview.stackexchange.com/questions/55554/parsing-sections-from-a-log-file-using-f