  We study small-scale brightenings in Ca II 8542 \AA\ line-core images to
determine their nature and effect on localized heating and mass transfer in
active regions. High-resolution 2D spectroscopic observations of an active
region in the Ca II 8542 \AA\ line were acquired with the GFPI attached to the
1.5-meter GREGOR telescope. Inversions of the spectra were carried out using
NICOLE. We identified three brightenings of sizes up to 2"x2". We found
evidence that the brightenings belonged to the footpoints of a microflare (MF).
The properties of the observed brightenings disqualified the scenarios of
Ellerman bombs or IRIS bombs. However, this MF shared some common properties
with flaring active-region fibrils or flaring arch filaments (FAFs): (1) FAFs
and MFs are both apparent in chromospheric and coronal layers according to the
AIA channels, and (2) both show flaring arches with lifetimes of about 3.0-3.5
min and lengths of about 20". The inversions revealed heating by 600 K at the
footpoint location in the ambient chromosphere during the impulsive phase.
Connecting the footpoints, a dark filamentary structure appeared in the Ca II
line-core images. Before the start of the MF, the spectra of this structure
already indicated average blueshifts, meaning upward motions of the plasma
along the LOS. During the impulsive phase, these velocities increased up to
-2.2 km/s. Downflows dominated at the footpoints. However, in the upper
photosphere, slight upflows occurred during the impulsive phase. Hence,
bidirectional flows are present in the footpoints of the MF. Conclusions: We
detected Ca II brightenings that coincided with the footpoint location of an
MF. The MF event led to a rise of plasma in the upper photosphere, both before
and during the impulsive phase. Excess mass, previously raised to at most
chromospheric layers, slowly drained downward along arches toward the
footpoints of the MF.
