DEEP-WATER SEDIMENTARY PATTERNS IN THE MIOCENE MARNOSO-ARENACEA FORMATION (ITALY) ASSOCIATED WITH SYN-SEDIMENTARY TECTONIC DEFORMATION

Deep-water turbidite systems respond at multiple scales to changes in seafloor gradient formed by tectonic deformation. Current stratigraphic models do not clearly link these multi-scale responses with orders of syn-sedimentary tectonic deformation to predict deposit heterogeneity. This study aims to improve predictive deep-water stratigraphic models for syn-sedimentary conditions. For this, 1.3 km of measured sections, 7.7 km of photo and geologic mapping, and 659 restored paleocurrent measurements were collected to document a sedimentological hierarchy of attributes in pre- and syn-kinematic turbidites of the Marnoso-arenacea Formation across the Coniale Anticline. Facies, event beds, and sedimentary bodies collectively define eleven sedimentary patterns that record the interaction between cumulative gradient, sedimentation intensity, and the event bed/receiving basin width ratio.

Two sedimentary patterns describe pre-kinematic domains. Low facies diversity in large waning-depletive event beds form a monotonous succession of sandstone elementary lobeform and mudstone drape bodies. There is high temporal steadiness and spatial uniformity attributes across the structure.

Nine patterns characterize syn-kinematic domains that have no cross-structure uniformity. In the wedge-top basin, off-structure regions exhibit low facies and grain-size diversity in thick, steady-depletive event beds that comprise sandstones-dominated weakly-channelized lobeform complexes. These attributes grade laterally into calcareous mudstone drapes in on-structure regions. Six syn-kinematic patterns of the foredeep basin contain a diverse facies and event bed assemblage in lobeform complexes and drape bodies. Cyclical spatial and temporal change in facies, paleocurrent, event beds, and body types form patterns that record episodic anticline growth.

Patterns establish correlation between scales of stratigraphic heterogeneity and orders of tectonic deformation. An increasing pattern number from pre- to syn-kinematic domains records increasing gradient complexity from anticline growth. This study supplements the pattern matrix of the AIGR stratigraphic model to enhance prediction of high-resolution architecture from low-resolution data on syn-kinematic structural features.