DLA 34 (Arenal) (Ordovician of Argentina)

Also known as Are 20/21

Where: Jujuy, Argentina (23.5° S, 65.3° W: paleocoordinates 44.8° S, 128.8° W)

• coordinate based on unpublished field data

• small collection-level geographic resolution

When: Rupasca Member (Santa Rosita Formation), Tremadocian (485.4 - 477.7 Ma)

• bed-level stratigraphic resolution

Environment/lithology: offshore; lithified, bioturbated, muddy siliciclastic sediments and lithified, silty, sandy siliciclastic

• Lower-offshore deposits consist of greenish grey, massive or thinly parallel-laminated mudstone. Mudstone units are laterally extensive, displaying sharp

•bases and are interbedded with grey, sharp-based, tabular, very thin, very fine-grained silty sandstone beds, exhibiting combined-flow ripple cross-lamination and symmetrical to near-symmetrical ripple tops. These deposits were formed in a low-energy setting, where suspension fall-out sedimentation was punctuated by rare, storm events (Buatois & Mangano 2003; Buatois et al. 2006). The presence of oscillatory structures in most of the interbedded sandstone layers indicates

•deposition immediately above storm-wave base. This environmental scenario is also supported by the scarcity of sandstone beds and the presence of thick

•mudstone intervals.

Size classes: macrofossils, mesofossils

Preservation: cast, mold/impression

Collection methods: bulk,

Primary reference: D. Balseiro, B. G. Waisfeld, and L. A. Buatois. 2011. Unusual trilobite biofacies from the Lower Ordovician of the Argentine Cordillera Oriental: new insights into olenid palaeoecology. Lethaia 44:58-75 [D. Balseiro/D. Balseiro]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 136935: authorized by Diego Balseiro, entered by Diego Balseiro on 07.12.2012

Creative Commons license: CC BY (attribution)

Taxonomic list

 Olenida - Olenidae
Leptoplastides sp. Raw 1908 trilobite
Parabolinella sp. Brögger 1882 trilobite
Bienvillia sp. Clark 1924 trilobite
Peltocare sp. Henningsmoen 1957 trilobite
 Asaphida - Asaphidae
Asaphellus sp. Callaway 1877 trilobite
 Asaphida - Remopleurididae
Pseudokainella sp. Harrington 1938 trilobite