(apologies in advance for the partial lack of diacritics, I am home, ill, with no access to a unicode keyboard)
The Saṅkarṣakāṇḍa (henceforth SK, about which see here) is an enigmatic text thought to complete the Mīmāṃsā Śāstra, after the Pūrva Mīmāṃsā Sūtra (henceforth PMS) and before the Uttara Mīmāṃsā Sūtra (or Vedānta Sūtra, henceforth UMS).
As for its origin, several witnesses speak of the SK as having been authored by Jaimini