Fieldwork

 

2022 - Field work in the Southern Carpathians

 

Several mid-Cretaceous successions were analyzed in the Southern Carpathians.

 

A section exposing the middle member of the Dumbrăvioara formation was investigated. It consists of gray marls interspersed with centimeter-sized limestones. In the deposits from the Upper Cenomanian - Lower Turonian interval, intercalations of black clays sedimented in a euxinic environment were identified.

Albian-Turonian hemipelagic deposits of the Dumbrăvioara Formation A – Middle Member; B – The Upper Member

 

Successions from the Dâmbovicioara region were studied. From a geological point of view, the Dâmbovicioara area (also known as Rucăr - Bran) belongs to the eastern part of the Southern Carpathians. This area contains one of the richest macrofauna (especially ammonites) in the Romanian Carpathians. Successions belonging to the Barremian-Aptian interval exposed in Dealul Sasului were studied. Also, the black marl formations with radiolarians, deposited at the Cenomanian-Turonian boundary interval, in an anoxic environment, indicative of the deposition of OAE2 (Oceanic Anoxic Event 2), were analyzed.

Panorama from Dealul Sasului - horsts and grabens in the Cretaceous deposits

 

2021 Field work in the Eastern Carpathians

 

In the Eastern Carpathians, several sections have been selected to be studied from licthological/sedimentological point of view, sampled and analyzed biostratigraphically and geochemical for identifying the overprint of OAE (Oceanic Anoxic Event) in the Albian-Turonian interval (the main aim of this project).

 

Southern part of the Eastern Carpathians

Lepşa Section (Vrancea Nappe – Vrancea Halfwindow)

Located nearby the confluence of the Putna and Tişiţa valleys, it exposes Cenomanian-Turonian sediments (age argued based on calcareous nannofossils), enclosing a prominent black shale lelvel, possibly OAE2.

 

The Lepşa section, where the sediments of the Tisaru Formation are cropping out

(Photo Dr. Relu-Dumitru Roban, August 2021).

 

Detail of the Lepşa section, containing a prominent black shale depositional interval.

(Photo Dr. Relu-Dumitru Roban, August 2021).

 

Central part of the Eastern Carpathians

 

In the aforementioned area, successions form the Inner Moldavide tectonic units (i.e., Audia Nappe) have been investigated. An interesting outcrop was observed at Hangu, on the left bank of the Bicaz River, upstream the Bicaz Dam.

 

The sediments of the Audia Nappe are cropping out, exposing the Upper Albian Member of the Audia Formation, as indicated by the calcareous nannofossil analysis. Several cm-thick black shale beds are present, possibly indicative of OAE1d.

 

Deposits of the Upper Member of the Audia Nappe (Albian in age) at Hangu (left bank of the Bicaz River), containing several dm-thick black shales

(Photo Dr. Gabriel Ion, August 2021).

 

Northern part of the Eastern Carpathians

 

Several mid Cretaceous successions were investigated from the northern areas of the Eastern Carpathians, for identifying black shales levels, possible lithological overprint of the Oceanic Anoxic Events.

 

On the banks of the Ostra River, thick turbidites successions of Inner Moldavide structures (i.e., the Audia Nappe) are cropping out. These are composed of dm-thick calcareous sandstones, rhythmically alternating with claystones and marlstones. In the outcrops, cm- up to dm-thick black shales levels are visible.

 

Mid Cretaceous successions exposing turbidites that contain dm-thick black shales in N Eastern Carpathians (Ostra Valley, near Stulpicani locality).

Photo Dr. Gabriel Ion, August 2021

 

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