Download 25. J.H. Westermann geological formations, being quite quartzdiorite

Aruba
25.
BY
J.H.
Westermann
With
In
the
the
island
Martin.
he succeeded
It
features¹).
sta y²)
Beside
is,
in
of
the
On
the
quoted publication by
island
island
of
and
age
Aruba
in
three
occur
nature
that
genesis
during
some
other
some
not worth
days
on
geological
geological
of
its
to
as
few
our
of
map
rocks.
geological
here
mentioning
all
formations,
being
quite
of rocks:
diabase-schist ssystem,
the
quartzdiorite-batholith
3.
the
limestone- and
for
determined.
group
the
Martin
the latter is
exists;
2.
Except
be
concerning
the
in
a
general
understandable
introduced
be
only
clear view of the
a
well
very
surveyed
was
stayed
great importance.
the
1.
Aruba
this surveyer
obtaining
ideas
map.
1885
year
could
older
the above
no
different in
in
however,
the
literature about
the
Although
corrections
some
Aruba and
being
of
beginning
geology by K.
geological
and
its
the youngest
the
one
ages
of
acceptance
a
certain
for
age
of
the
formations
with other islands
correlation, bowever,
In
differentiates,
detritus-formation.
the
first
two
could
not
of the Antilles-
formations
seems
possible.
The oldest
Cretaceous
of
system,
in
age,
the diabase
the
diabase-schist-complex,
relation
with
Curacao and
on
the
acceptance
of other
resembling
is
of
supposed
the
to
be
Cretaceous
rocks
in
of
age
several other
Antilles-islands.
the intrusion of the
Consequently,
schist-complex
*)
„Bericht
gründete
2
)
must
über
Studiën".
In
the Lesser
University
of
eine
Leiden,
connection
Antilles
have taken
in
with
the
Utrecht,
Eeise
E.
the
J.
Niederlanidisch
of
into the diabase-
or
West-Indien,
older
und
Tertiary
darauf
ge-
1888.
geological
summer
Holland.
nach
Brill,
quartzdiorite-magma
in youngest Mesozoic
place
1930
excursion
under
the
to
the
Dutch
leadership
of
Leeward
Prof,
Dr.
Islands
L.
of
Rtjtten.
710
time.
This agrees
with
the age of similar intrusions in other
West-Indian
islands.
youngest formation is
The
The
1.
island;
Quaternary
a
diabase-schist-system
smaller
some
the
(occurrence:
in
regions
the
N. W.
far
as
one,
is
as
middle
and
corner
known.
of
part
the
near
the
East-
coast).
It
is
striking
a
this formation
the
as
the
of
the
hills
of
the
oldest
The
"
the
of
rocks
of
of
varying,
are
an
to
the
The
on
diabases
before
that
The
augite
with
of
coloured rocks, that
system
after
As
the
mentioned
The
diorite,
diorite
Both
hatholith
—
with
rocks
these
of
a
great
dips
although
vertical
a
in-
masses
all
very
position.
extruded
or
discordant
as
that
way
almost
are
show
a
strata,
of
this
system;
and
hornblende,
masses
into
changed
with
locally
the
of
many
do
uralite
them
contain
not
(in
con-
of
intrusion
mentioned
gray-
the
are
the
Besides,
and
the
grayish-green-
were
most of these
May be,
altered tuffs occur,
hardly
transitional between these
Rocks,
tuffs
and the
found.
not
amphibolites,
that
found
are
especially
island.
this
formation
can
be
possibly
and
Curacao,
on
by
also
are
found
dioritic
the
with
plagioclaseshow
a
as
with
compared
the
small exogenous
Due
magma.
the
to
hornblende-schists and
(diabases,
amphibolites
the
and
Washikemba-
of
small,
inclusions
same
in
the
magma
the
amphibolites)
have
quartz-material,
network
inclusions
exogenous
diabases
have
heen
and
took
part
of
place
the
in
schists
intrusive
diabase-schist-system.
roof-foundering
case
of
such
been
whereas
injected
show
enriched
by
nearer
the
quartz-plagioclase-
rocks").
the
must
the
Most
composed
folding.
been
he
must
contactmetamorphism:
these
morphism
than
up
("hybrid
veins
the
;
be called hornblende-schists.
above,
older rocks
magma
hills
Bonaire.
on
taken
certain
the
and
and
Knip-formation
amphibolites
marginal
found
Arikok
the
\iralite-diabase.
:
rocks
corner
diabase- and
formation
a
schistose
N. W.
in
of the
and, besides,
the
having
folding
with Radiolaria.
Other
the
erosion,
are
(155 m).
these
folded,
strata
great part
a
above mentioned hornblende-schists
in
Tonel
than
concordant
as
plagioclase
rocks
can
E
some
from tuffaceous sediments.
originated
probably
90
North;
mineral
magma)
schistose
the
the
strong
dioritic
younger
Of
the
Gran
The strikes
about N
the
constitute
this
anymore,
nection
strongly
are
recognized.
extruded
chiefly
the
lower
selective
in which
(188 m),
Jamanota
and
are
folding-processes,
or
diabases
composed
are
to
in
the
in-
probably
the
(170m)
average
or
occur
during
or
island
system
cannot be
South
the
Aruba.
this
individual folds
steep
of
consequence
mountainous'' landscape,
diorite-landscape
the
rocks
a
Kabaai
Seroe
in
in
that,
as
points
highest
(185m),
fact,
outcrops
It
the
make
into
is
—
diorite and
it
ohvious
and
impossible
thus
to
say
the
that
must
(the
older
rocks)
must
the
be
whether
during the batholitic intrusion,
roof
contactmeta-
or
have
dioriteyounger
a
not.
been
partial
In
any
eroded
711
712
after
diorite-intrusion,
the
island is
of the
2.
The
The
the
to
taken
fact that
of
The
the
place
the
strike
in
the
themselves,
diorite has
older
been
"
curious
Very
the
high
Bientoe
more
a
85
—
less
beautiful,
crystals
m
are
"
of
fragments
magma
intruded.
igneous
common
The
in
of
rock
in
diorite-dikes
even
is present.
occur,
wide
and
of
long
being
even
rock
worth
as
on
this is also
because
found
rocks
Aruba
are
must
true for
only
one
(near Seroe
batholithroeks
hills
average
the older
found
are
and
its
this
second
of
in
the
not
"rock
"rock
must
dioritic
former,
constitutes
batholith.
the first
Two
kinds
place quartz-
Granodiorites,
occur.
In
so
Aruba either.
on
are
sequence
rocksystem.
far
latter
Through
that enclose
Hooiberg
wanting
magmatic
not,
two
minerals.
quartz-hornblende-augite-
there
are
of
quartz-hornblende-diorite.
and
and
are
constituent
the
quartzdiorite.
place
in the older
that
main
"Hooiberg
dioritic
i.
hornblende-
big
the
(f.
Seroe
composed
diorites,
"
the
;
obviously
are
quartz;
and
aplites
steep hills
many
ferromagnesian
the
America,
found
as
the latter rocks
down the top of the batholith
can
met
exist
Bonaire,
Grita
as
recognized
with.
in
as
Hence,
the
but
of
porphyritic
Curacao
on
Kabai)
far
be
These dikerocks
running
are
a
and
about the
a
same
of that
island.
Possibly
deeper,
has
others of the nature of the
known.
and
intrusive
still
quartz-hornblende-diorite-dike
no
rocks.
dikerocks
similar batholithic
underground
the
vintliths;
lamprophyric
there the batholith must lie
and
is
and
through
dike-diorites, dike-
(quartz-)diorite-porphyrites
that
outcrop
occur,
an
diorite-mono-
that
),
—
which
that the
in
transitional between
mentioning
dioritic
the
folding.
of
Oranjestad
consolidation of
here
dikes
dike-granodiorites,
is
in
m
that is to say,
the
proving
granites,
It
of
the
in the northern- and north-eastern-part of the island
the
latter
that
which
several
These
the batholith is
several hundred meters.
over
belong
as
exfoliated
are
98
—
biotitegranites
and also
Especially
numerous
rocks
parts
diorite,
rocks;
also
during
in
one,
and
Therefore,
assumed,
representatives
younger
the
same
Furthermore,
the
(-hypersthene)-(biotite)-gabbro's
dikes
older
(that
landscape
from
east
dikes of
After
quartzdiorites,
wellknown in other
these
low level with
flat
a
rock,
"rock.
be
hornblende-biotite-diorite,
the
is
the
from the
plagioclase
quartzdiorite have been found,
Beside
rather
a
after the
many
diorite.
may
surface
diabase-schist-system
of
intrusion
erosion.
striking.
Hooiberg
It
an
Wara
pyroxene,
run
about
to
—,
first-solidification-differentiation
The most
of
"
older than the
be
a
the
m
Wara
crystallized
"rock
Hooiberg
is
diorite-landscape
selective
particularly
minerals must have
this
the
by
monoclinic
the
folding
rounded off
164
—
darkcoloured,
are
minerals
and
—
preserved
the
diorites.
the
pillowstructure).
the flat
Hooiberg
cony
or
in
the
in distinction
generally
("Wollsackbildung",
liths
point
big
by
porphyrite-dikes
the
denuded to
Felsenmeere" of
into
magma
rocks
to
seems
diorite-landscape
the
numerous
of
but
differentiates.
during
or
of
greater part
older rocks
its
dioritic
altitude of about 40 m; and
rocks
and
the
today
the
by
after
general
batholith)
the
older rocks
that
so
not
diorite-batholith
intrusion
have
must
occupied
been
Aruba-
713
Still younger dikerocks
leucocratic rocks.
The
melanocratic
are
latter show
aplites, granitic aplites, granodioritic
and
The
3.
veins
in
The
and
only
or
limestone
remains
it,
further
as
frequently
Probably
seperated
by
limestone
has
time
the
surrounding
the
The
lower
in
covered
r
of
at
situation;
the
as
has been
whole
(East)
its
The
layers
must
island
or
part,
and
coast.
distinguished,
place.
places
horizontal
a
Westcoast,
be
took
limestone
a
part
North
can
levels
the
over
and
only
Southeastern
the
along
these
deposition,
or
South- and
many
this
that
limestone-cap
bordering
of
changes
limestone is present
younger
terrace
in the
limestone-deposition
which
the
limestone-covering
the
border
both
"Whether the whole
during
The
the two
on
limestone
whole island
especially
ide, along
indicating
sea,
the
the present,
is found
w
the
partly denuded.
interrupted
highest
arched
slightly
a
of it.
it
periods
two
a
as
quartz-rocks,
unconformably
of
under sealevel
was
for
today
occurring
are
epidote-rocks.
lies
deposition
haA'e been
about 2 km
zone,
a
narrow,
a
the
formerly
questionable
denuded and
partly
rocks,
rocks,
detritus-formation.
Before
part of it
a
and
(partij' coral limestone)
older roekformations must
whether the
eruptive
epidote-quartz-rocks
limestone-
The limestone
island
postmagmatic
the above-mentioned
older roekformations.
to
and
malchites,
constitute dioritic
aplites, quartz-albitites, gabbro-aplites
and
magmatic
youngest
very
and
quartz-epidote-rocks,
as
and
pegmatites.
dikes
of
usually
ones,
great variety,
a
to
belonged
have
or
older
dip
over
a
part
nearly horizontal
island.
LamelliIn
several
Corals,
places many fossils have been found,
At the S. E.
branchiates and Gastropodes.
the
limestone became
Large
and
water
lies
difficult
to
it
geological
younger
of
Curasao).
These
greater
of
a
be very
been
never
and
can
the
be
presence
of
of
(uplifted?),
also
it
is
limestone-covering
characterized
negative
a
by
several
(compare
way
occur
on
and
the island;
diorite-monoliths,
long, frequently interrupted shore-coralreef,
sealevel
course
distinguished by considering
in the
coves
detritus
there.
was
in
This
Southcontain
young; it is
limestone;
places
of Aruba
positive
consequence of the N. E.
In
along
the
wavecut
chasms
front
the
reef
certain
has
diorite-hills.
that
rising
before
lying
and
and
the
for the
parallel
Southcoast.
the
develop
a
low
younger
movements
young
the
above
part
in
the
the
along
rivers
(small
the limestone and the diorite-detritus
by considering
occurrence
a
especially
occur
accordingly
the
history
both in
level,
in which
under
whether it
or
way
from
whether
The
with
to
partly
lies
Aruba, Seroe Colorado,
of
the "rooien"
by
season)
disappeared,
changes
the
rainy
determine
slow
also
there
point
phosphorite.
diorite-detritus
brought
the
into
the limestone and must
on
that
possible
has
in
only
partly
of
deposits
Westcoast,
changed
of
could
N.,
and
coves
Westcoast
not
N. E.
grow
occur
only
here
and
and
E.
E.
in
the
separate
because
tradewinds
coasts;
hut
rocks,
the
coralstocks
of
the
sandy
a
eoralreef coulcï
there
many
soealled "boea's".
are
met
with;
seabottom.
not
undercuts,
In
possibly
714
The
of
They
rence.
and E.
bay
the
a
has been
that
is
Nicolaas),
for
the
these
in
the
the
say
the
and
to
the
are
gold
Also
the
sea
can
and
some
beginning
or
since
almost
from the
about
in
digging
the
new
away
concrete
Seroe
cement.
(N.E.
inland-
in distinction
;
century
many
the
exploitation
came
have been
(the
Oranjestad
sand"
Aruba
goldbearing
Colorado
highway-construction
"fresh
occur-
dry.
1914
road between
of socalled
and
coasts
handshaped
workings other soil-exploitations
quartz for
W.
of the twentieth
partly
composed
the place of
be found in Aruba
entirely
won
coastdunes,
on
N.E., E.
phosphateworking
foundation of
fabrication of
the
(Schottegat)
either
was
are
depending
the
on
Curasao
the mining of
the
both,
diorite-batholith;
Instead of these
in
in
nineteenth and in the
stopped.
is to
used
As
gold;
of
or
especially
junctioncanal
some
quartzdikes
end.
found
Schottegat
In the
exported
an
quartz-sand
tradewinds).
's with
from
are
features
geological
youngest
very
limestone-sand,
to
started;
quartz
and
Sint
(diorite-sand)