  Identifying the source of the material within coronal mass ejections (CMEs)
and understanding CME onset mechanisms are fundamental issues in solar and
space physics. Parameters relating to plasma composition, such as charge states
and He abundance (\ahe), may be different for plasmas originating from
differing processes or regions on the Sun. Thus, it is crucial to examine the
relationship between in-situ measurements of CME composition and activity on
the Sun. We study the CME that erupted on 2014 September 10, in association
with an X1.6 flare, by analyzing AIA imaging and IRIS spectroscopic
observations and its in-situ signatures detected by Wind and ACE. We find that
during the slow expansion and intensity increase of the sigmoid, plasma
temperatures of 9 MK, and higher, first appear at the footpoints of the
sigmoid, associated with chromospheric brightening. Then the high-temperature
region extends along the sigmoid. IRIS observations confirm that this extension
is caused by transportation of hot plasma upflow. Our results show that
chromospheric material can be heated to 9 MK, and above, by chromospheric
evaporation at the sigmoid footpoints before flare onset. The heated
chromospheric material can transport into the sigmoidal structure and supply
mass to the CME. The aforementioned CME mass supply scenario provides a
reasonable explanation for the detection of high charge states and elevated
\ahe\ in the associated ICME. The observations also demonstrate that the
quasi-steady evolution in the precursor phase is dominated by magnetic
reconnection between the rising flux rope and the overlying magnetic field
structure.
