issue_comments: 1530186148

@kmuehlbauer - I ran https://github.com/pydata/xarray/issues/7790#issuecomment-1529894939 and I get an incorrect fill value:

```

Created with fill value 1900-01-01 <xarray.DataArray 'time' (time: 2)> array([ 'NaT', '2023-01-02T00:00:00.000000000'], dtype='datetime64[ns]') Coordinates: * time (time) datetime64[ns] NaT 2023-01-02

Read back out of the zarr store with xarray <xarray.DataArray 'time' (time: 2)> array(['1970-01-01T00:00:00.000000000', '2023-01-02T00:00:00.000000000'], dtype='datetime64[ns]') Coordinates: * time (time) datetime64[ns] 1970-01-01 2023-01-02 {} {'chunks': (2,), 'preferred_chunks': {'time': 2}, 'compressor': Blosc(cname='lz4', clevel=5, shuffle=SHUFFLE, blocksize=0), 'filters': None, '_FillValue': -2208988800000000000, 'units': 'nanoseconds since 1970-01-01', 'calendar': 'proleptic_gregorian', 'dtype': dtype('int64')}

Read back out of the zarr store with zarr <zarr.core.Array '/time' (2,) int64 read-only> <zarr.attrs.Attributes object at 0x132802a50> [-2208988800000000000 1672617600000000000]

and here is my show_versions, since it may have changed because I've added some new libraries. It looks like my ipython version is slightly different, but I can't see how that would affect things. INSTALLED VERSIONS

commit: None python: 3.11.3 | packaged by conda-forge | (main, Apr 6 2023, 08:58:31) [Clang 14.0.6 ] python-bits: 64 OS: Darwin OS-release: 22.4.0 machine: arm64 processor: arm byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: ('en_US', 'UTF-8') libhdf5: None libnetcdf: None

xarray: 2023.4.2 pandas: 2.0.1 numpy: 1.24.3 scipy: None netCDF4: None pydap: None h5netcdf: None h5py: None Nio: None zarr: 2.14.2 cftime: None nc_time_axis: None PseudoNetCDF: None iris: None bottleneck: None dask: None distributed: None matplotlib: None cartopy: None seaborn: None numbagg: None fsspec: None cupy: None pint: None sparse: None flox: None numpy_groupies: None setuptools: 67.7.2 pip: 23.1.2 conda: None pytest: None mypy: None IPython: 8.13.1 sphinx: None ```