  Kepler's supernova remnant (SNR) is believed to result from a Type Ia
supernova, but be interacting with dense circumstellar material (CSM), which
makes its progenitor system a mystery. Using the Chandra ACIS-S 741 ks
effective exposure data and an advanced adaptive binning algorithm, we analyse
the spectra from tessellated regions in Kepler's SNR. For the first time, we
map out the detailed spatial distributions of emission measure (EM), electron
temperature, ionization parameter, and metal abundances for both the low- and
high-temperature plasma components. The low-temperature plasma diverges into
two branches in the temperature v.s. ionization parameter diagram, which appear
to be spatially associated with the warm CSM dusts and the Si- and S-rich
ejecta, respectively. We construct the probability distribution functions of
abundance ratios of O and Mg to L-shell emitting Fe ([O]/[Fe]$_{\rm L}$ and
[Mg]/[Fe]$_{\rm L}$), and fit them with double Gaussians. Thereby, we
distinguish the CSM from the ejecta: the CSM is characterized by [O]/[Fe]$_{\rm
L}$ $= 0.77^{+0.30}_{-0.23}$ and [Mg]/[Fe]$_{\rm L}$ $= 1.11^{+0.46}_{-0.32}$,
while the ejecta by [O]/[Fe]$_{\rm L}$ $= 0.31^{+0.17}_{-0.10}$ and
[Mg]/[Fe]$_{\rm L}$ $= 0.38^{+0.36}_{-0.19}$. We estimate the total hydrogen
mass of the shocked CSM as $\sim 1.4 M_\odot$ and the EM-weighted mean [Mg]/[O]
$= 1.14 \pm 0.49$, which can be reproduced with an asymptotic giant branch
donor star with initial mass of $\sim 4 M_\odot$. The abundance ratios from the
shocked ejecta are well compatible with the predicted results from spherical
delayed-detonation models for Type Ia supernovae. We also find that the two
`ears' of the remnant are dominated by Si- and S-rich ejecta, thus favoring a
pre-explosion jets scenario.
