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TIME IN MA MAGNETOSTRAT. AMMONITE ZONES CALCAREOUS SEA LEVEL LONG-TERM AND TIME IN MA
PERIOD POLARITY NANNOFOSSIL EVENTS SHORT-TERM
EPOCH STAGE CHRON
ZONES (Sequence Boundaries) SEA-LEVEL-CURVES

TETHYAN BOREAL TETHYAN BOREAL [Movement of Shoreline]

S. STENOMPHALUS (NJT) (NJ) BASINWARD 250 200 150 100 50 0 m -50
S. ICENII LANDWARD
140 140
145 R. RUNCTONI
150 CRETACEOUS M16 S. BOISSIERI 141.8 KBe3
155 M17 S. OCCITANICA
160 BERRIASIAN CC2
165
170 M18 B. JACOBI S. LAMPLUGHI CC1 143.9 KBe2 145
175 M19 DURANGITES S. PREPICOMPHALUS NJT17b 144.7 KBe1
NJT17a 150
TITHONIAN M20 M. MICROCANTHIUM S. PRIMITIVUS NJT16b NJ18 146.2 JTi7 APPROXIMATE PRESENT-DAY SEA LEVEL
M21 P. PONTI/B. PERONI P. OPPRESSUS NJT16a NJ17b 147 JTi6 155
T. AUGUIFORMIS NJT15b NJ16b 147.9 JTi5 Short-term
M22 S. FALLAUXI G. KERBERUS G. OKUSENSIS NJT15a NJ16a 148.7 JTi4
G. GLAUCOLITHUS NJ15b 149.3 JTi3 curve
S. SEMIFORME NJT14
S. DARWINI P. ALBANI NJ15a 150.4 JTi2 160
V. FITTONI NJ14
H. HYBONOTUM P. ROTUNDA 151.5 JTi1

JURASSIC M22A H. BECKERI P. PALLASOIDES 152.7 JKi7
L AT E M23 P. PECTINATUS
A. EUDOXUS P. HUDLESTONI
KIMMERIDGIAN M24 A. ACANTHIUM P. WHEATLEYENSIS 153.8 JKi6
154.5 JKi5
MIXED M24A C. DIVISUM P. SCITULUS
POLARITY M24B A. HYPSELOCYCLUM P. ELEGANS 155.3 JKi4
M25 A. AUTISSIODORENSIS 155.7 JKi3
M25A S. PLATYNOTA 156.1 JKi2
I. PLANULA A. EUDOXUS
M26
A. MUTABILIS 156.8 JKi1
LT.
OX-N R. CYMODOCE 157.3 JOx8
157.7 JOx7
P. BAYLEI

E. BIMAMMATUM

R. PSEUDOCORDATA

LT. P. BIFURCATUS NJT13b 158.8 JOx6
OX-R G. TRANSVERSARIUM
P. CAUTISNIGRAE
OXFORDIAN HIGHLY MID P. PUMILUS 159.9 JOx5
VARIABLE OX-M 160.4 JOx4
POLARITY PERISPHINCTES PLICATILIS 160.8 JOx3
CAR-N 161 JOx2
CARDIOCERAS CORDATUM Long-term
161.8 JOx1 curve

E. OX-M QUENSTEDTOCERAS MARIAE NJT13a

E. OX-N 163.1 JCa6

QUENSTEDTOCERAS LAMBERTI

E. CORONATUM P. ATHLETA P. ATHLETA NJ13 164 JCa5
R. ANCEPS NJ12b
CALLOVIAN K. JASON E. CORONATUM NJT12 NJ12a 164.5 JCa4
BATHONIAN M. GRACILIS S. CALLOVIENSE
BAJOCIAN NJ11 165.1 JCa3 165
P. KOENIGI 165.4 JCa2 170
AALENIAN NJ10 165.8 JCa1 175
TOARCIAN B. BULLATUS M. HERVEYI NJ9
NJ8b
C. DISCUS H. RET C. DISCUS O. ORBIS
H. RETROCOSTATUM C. BREMEN P. HODSONI NJ8a
MIDDLE 166.7 JBt3
M. MORRISI T. SUBCONTRACTUS NJ7 167.2 JBt2
P. PROGRACILIS
NJT11 168 JBt1
P. AURIGERUS Z. ZIGZAG
Z. ZIGZAG NJT10b
NJT10a
P. PARKINSONI P. PARKINSONI
NJT9
HIGHLY BAJ. G. GARANTHIANA NJT8c 168.9 169.1 JBj4
VARIABLE M JBj3
POLARITY S. NIORTENSE
169.5 JBj2
S. HUMPHRRIESIANUMS. PROPINQUANS

W. LAEVISCULA H. DISCITES 170.3 JBj1

U. AA-R G. CONCAVUM
MID AA-N
B. BRADFORDENSIS

M. AA-R LUDWIGIA MURCHISONAE 171.9 JAa3

NJT8b 172.6 JAa2

TO AA-N LEIOCERAS OPALINUM 173.3 JAa1

UP. TO-N PLAYDELLIA AALENSIS NJT8a
NJT7b
D. PSEUDORADIOSA D. LEVESQUEI 174.7 JTo10
P. DISPANSUM

MAJOR CYCLE BOUNDARY 250 200 150 100 50 0 m -50

MEDIUM OR MINOR CYCLE BOUNDARY

POTENTIAL CYCLE BD. (NOT YET CONFIRMED)

Figure 2. Middle–Late Jurassic sequences and variations of the sea level. (See Fig. 1 caption for details.)

in the outcrop sections (when sedimenta- sections (see discussion in Haq, 2014). falls are considered as major, with draw-
tion rates can be calculated), and some- Fifty-six third- and eight fourth-order con- down of more than 75 m (JSi4 in
times when oxygen-isotopic data are avail- sistently occurring events have been iden- Sinemurian; JPl2 and JPl8 in Pliensbachian;
able that show distinct excursions from the tified in the Jurassic of the sub-boreal and JAa2, JAa3 in Aalenian; JBj1 at the base of
overall trends (see the GSA Data Repository Tethyan regions, of which 25 are additional Bajocian; JOx1, JOx5, JOx6, JOx7 in
[see footnote 1]). The magnitude (ampli- to the older synthesis (Haq et al., 1988). Oxfordian; JKi7 in Kimmeridgian; and
tude) of sea-level falls as shown on the Three events in the Toarcian (JTo5–JTo7) JTi3, JTi4, JTi5 in Tithonian). All other
curves is, however, more difficult to esti- are included here tentatively, pending events are within the medium or minor
mate and has to be averaged from several wider confirmation. Fourteen sea-level range. The amplitude of sea-level falls is

8 GSA Today | January 2018