Loups Marins suites are major components of the
NESP, covering several hundreds of square kilometers (17) (fig. S4). The presence of 142Nd/144Nd
deficits in these young granitoids from widespread tonalitic units suggests that reworking of
Hadean mafic crust played an important role in
the generation of the felsic rocks that built the
core of the northeastern Superior craton.
The geochemical and 146-147Sm-142-143Nd com-
positions of the Hudson Bay terrane Eoarchean
to Neoarchean granitoids have important impli-
cations for the nature of Earth’s earliest crust and
for the processes involved in at least the initial
formation of the Superior craton. The occurrence
of felsic rocks with and without m142Nd anom-
alies shows that the remelting of preexisting crust-
al materials of different origins was involved in the
crust-building process, indicating a complex crust-
al reworking history of Hadean mafic crust, but
also early Archean crust, to create the northeast-
ern Superior craton. The 142-143Nd isotopic com-
position of the tonalitic rocks presented here
implies that multiple remelting events occurring
over a billion-year interval from ~3.8 to ~2.7 Ga
of an original widespread Hadean mafic crust
were an important process in forming at least
the northern segment of the Archean Superior
craton. Although 142Nd data of sufficient precision
to resolve similar contributions in other Archean
terranes are not yet abundant, the involvement
of a Hadean mafic crust as source of early felsic
magmatism is supported by the Hf isotopic com-
position of the least-altered Jack Hills Hadean
zircons (23–26) and the negative m142Nd values of
the ~3.9-billion-year-old Acasta gneisses (6). The
Hadean crustal signature clearly resolved in the
Neoarchean granitoids of the NESP indicates
that a Hadean mafic crustal progenitor survived
for more than 1 billion years in this area, spo-
radically producing tonalitic magmas through re-
melting over almost the entire Archean eon. An
implication of this result is that not all of Earth’s
first crust was lost from its surface but instead
served as the source of at least some of the oldest
continental crust on Earth.
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We thank the Ministère Énergie et Ressources Naturelles (MERN)
of the Québec government for providing most samples analyzed
in this study, D. Milidragovic and D. Francis from McGill University
for providing two granitoid samples, and three reviewers for helpful
comments. This research was supported by a Natural Sciences
and Engineering Research Council of Canada Discovery grant
to J.O. (RGPIN 435589-2013) and MERN contribution no. 8449-2016-
2017-01. All data are available in the supplementary materials.
Materials and Methods
Figs. S1 to S4
Tables S1 to S3
17 June 2016; resubmitted 12 October 2016
Accepted 13 February 2017
1202 17 MARCH 2017 • VOL 355 ISSUE 6330 sciencemag.org SCIENCE
Fig. 4. Initial e143Nd and m142Nd
versus age for the Hudson Bay
terrane felsic samples. Data for
the Paleoarchean to Eoarchean
samples are from (7, 8). Data
for the Neoarchean samples are
from this study, with the points
showing the calculated initial
isotopic composition for each
sample based on their age and
measured Sm/Nd ratios and Nd
isotopic compositions. Dark gray
circles denote samples with
resolvable m142Nd anomalies.
Light gray circles denote samples
with m142Nd < –5 overlapping
(within error) the JNdi-1 standard
(m142Nd = 0) with an external error
of 5 ppm. White circles denote
samples without m142Nd anomalies
(m142Nd > –5). Any sample with
a 142Nd anomaly requires a
precursor extracted from the
mantle before the extinction of
146Sm (gray vertical field). Small
gray numbers are 147Sm/144Nd for
different evolution lines. CHUR,
chrondritic uniform reservoir.
(A) This panel includes Neoarchean
granites-granodiorites. All but one
Neoarchean granitic sample
yielded no m142Nd anomaly,
requiring a precursor formed
after the extinction of 146Sm. The
147Sm/144Nd range from 0.089
to 0.113 is the measured range for
the Nuvvuagittuq Eoarchean TTGs
(7, 8). (B and C) These panels
include the TTGs surrounding the
NGB and Neoarchean tonalites-trondjhemites. The 142-143Nd compositions are consistent with
Hadean mafic precursors such as
the mafic rocks from the NGB.
Mafic and felsic reservoirs are
derived between 4.1 and 4.3 Ga
with 147Sm/144Nd ranges found in
the NGB mafic rocks (7). Plotted
142Nd values are normalized to modern mantle (m142Nd = 0).
4 2N d