  We study a class of quantum measurement models. A microscopic object is
entangled with a macroscopic pointer such that a distinct pointer position is
tied to each eigenvalue of the measured object observable. Those different
pointer positions mutually decohere under the influence of an environment.
Overcoming limitations of previous approaches we (i) cope with initial
correlations between pointer and environment by considering them initially in a
metastable local thermal equilibrium, (ii) allow for object-pointer
entanglement and environment-induced decoherence of distinct pointer readouts
to proceed simultaneously, such that mixtures of macroscopically distinct
object-pointer product states arise without intervening macroscopic
superpositions, and (iii) go beyond the Markovian treatment of decoherence.
