Morphological development of basin-scale silica diagenetic fronts revealed with 2D seismic reflection data: offshore Sakhalin, Russian Far East

Abstract

Two-dimensional (2D) seismic reflection data reveal two silica diagenetic boundaries located in the North Sakhalin Basin, offshore Sakhalin Island. These boundaries form distinctive high-amplitude seismic reflections that predominantly cross-cut Miocene stratigraphy. The boundaries represent the opal-A to opal-CT (cristobalite and tridymite) transition and the subsequent deeper opal-CT to quartz transition and cover an area of c . 107 000 km 2 . The reflections represent diagenetic reaction fronts that advance through silica-rich host sediments during burial. The oldest strata within which the diagenetic fronts have been identified are of Miocene age and the fronts commonly show a parallel relationship to a Late Miocene unconformity. These diagenetic fronts develop a variety of morphological forms. In the North Sakhalin Basin these front geometries are probably the result of the interference of the diagenetic fronts with inclined and folded stratigraphy together with lateral changes in the composition and, therefore, depth of transformation of the sediment. We define criteria for the recognition of these 2D cross-sectional morphological elements and by so doing provide the basis for the objective description and categorization of diagenetic front geometry.

The limited suitability of silica diagenetic boundaries as isothermal markers: Insights from seismic reflection imaging, Offshore Sakhalin, Russian Far East

“…Hein et al, 1978;Volpi et al, 2003), however others are not (e.g. Brekke et al, 1999;Davies and Cartwright, 2002;Meadows and Davies, 2007). Instead they are parallel to prominent unconformities.…”

“…The diagenetic conversions of silica are important reactions in siliceous rocks within sedimentary basins (Hesse, 1990). Diagenetic silica conversions have been identified from a number of different sedimentary basins worldwide (e.g., Nobes et al, 1992a;Bohrmann et al, 1994;Davies and Cartwright, 2002;Meadows and Davies, 2007;and references therein).…”

“…The changes in physical properties, resulting from the conversions, cause an increase in the acoustic impedance at the diagenetic boundaries compared to the surrounding sediments. This gives rise to a seismic reflection that can cover areas of at least 10 4 -10 5 km 2 of sedimentary basins (Nobes et al, 1992b;Davies and Cartwright, 2002;Meadows and Davies, 2007), which can cross-cut inclined stratigraphy (Hein et al, 1978;Davies and Cartwright, 2002). The diagenetic boundaries form normal polarity, high-amplitude seismic reflections.…”

Hemipelagic deposits on the Mendeleev and northwestern Alpha submarine Ridges in the Arctic Ocean: acoustic stratigraphy, depositional environment and an inter-ridge correlation calibrated by the ACEX results

“…Silica-rich sediments are abundant in the Paleogene and older sediments recovered in short cores from Alpha Ridge (Mudie et al 1986), and strong reflections can also be produced by diagenetic fronts such as opal-A to opal-CT transition (Hesse 1990;Guerin and Goldberg 1996). The acoustic response is a bottom simulating reflection of moderate to high amplitude and positive polarity (Hein et al 1978;Davies and Cartwright 2002) that may cross-cut depositional surfaces (Davies and Cartwright 2002;Meadows and Davies 2007). The top of the lower double-cycle reflection bands (MRB2 and ARB3) on the Mendeleev and northwestern Alpha Ridges appears to be a positive amplitude reflection with a seismic signature similar to the planar diagenetic front described by Davies and Cartwright (2002) and Meadows and Davies (2007).…”

“…The acoustic response is a bottom simulating reflection of moderate to high amplitude and positive polarity (Hein et al 1978;Davies and Cartwright 2002) that may cross-cut depositional surfaces (Davies and Cartwright 2002;Meadows and Davies 2007). The top of the lower double-cycle reflection bands (MRB2 and ARB3) on the Mendeleev and northwestern Alpha Ridges appears to be a positive amplitude reflection with a seismic signature similar to the planar diagenetic front described by Davies and Cartwright (2002) and Meadows and Davies (2007). The lower reflection bands (MRB2 and ARB3) have constant amplitude, show no cross-cutting relationships, and MR2B is present in grabens where it is much deeper buried.…”