The Lower Tri
assic sediment
ary
and c
arbon
ate/org
anic c
arbon isotope records from the Tulong
are
a (South Tibet)
are documented in their integr
ality for the first time. New
age control is provided by
ammonoid
and conodont biostr
atigr
aphy. The b
as
al Tri
assic series consists of Griesb
achi
an dolomitic limestones, simil
ar to the K
athw
ai Member in the S
alt R
ange (P
akist
an)
and to the Otocer
as Beds in Spiti (Indi
a). The overlying thin-bedded limestones of Dieneri
an
age strongly resemble the Lower Cer
atite Limestone of the S
alt R
ange. They
are followed by
a thick series of d
ark green, silty sh
ales of Dieneri
an–e
arly Smithi
an
age without f
aun
a th
at strikingly resemble the Cer
atite M
arls of the S
alt R
ange. This interv
al is overl
ain by thin-bedded, light grey fossil-rich limestones of middle to l
ate Smithi
an
age, resembling the Upper Cer
atite Limestone of the S
alt R
ange. These
are followed by
a sh
ale interv
al of e
arly Sp
athi
an
age th
at h
as no direct counterp
art in other Tethy
an sections. C
arbon
ate production resumes during the l
ate e
arly
and middle Sp
athi
an with the deposition of red, biocl
astic nodul
ar limestone (“Ammonitico Rosso” type f
acies). Ap
art from its colour this f
acies is simil
ar to the one of the Niti Limestone in Spiti
and of the Sp
athi
an nodul
ar limestone in Gu
angxi (South Chin
a). As in other Tethy
an loc
alities such
as Spiti, the e
arly–middle Anisi
an p
art of the Tulong section is strongly condensed
and is ch
ar
acterized by grey, thin-bedded limestones with phosph
atized
ammonoids.
As for many other Tethyan localities the carbon isotope record from Tulong is characterized by a late Griesbachian–Dienerian positive δ13Ccarb excursion (2‰), and a very prominent positive excursion (5‰) at the Smithian–Spathian boundary, thus confirming the well-documented perturbations of the global carbon cycle following the Permian–Triassic mass extinction event.