Styles and Productivity of Mud Diapirism along the Middle American Margin

Abstract

Abstract:We present sedimentological and structural data and conceptual models for the evolution of two types of diapiric mud moundss offshore Costa Rica. Dozens of exposed mud mounds are found in the smooth domain of the margin with Mound Culebra being the most prominent example. Mound Culebra is a fault controlled feature with steep flanks (~10-20°) and a lack of recent mud flows. The extruded material consists of overcompacted silty clay with signs of intense brittle deformation, brecciation, hydrofracturing and secondary perforation by closely spaced conduits. The southern rough domain is characterized by numerous local tectonic regimes linked to seamount subduction and the collision of the Cocos ridge all associated with diverse forms of venting. Diapirism seems to play only a minor role and Mound 11 and 12 are examples of fault controlled, low relief mud volcanoes with shallow-dipping flanks. Mud flow sequences, vent debris and the presence of gas hydrates in the shallow subsurface favor an episodic, gas driven eruption behavior.

Late Miocene seep-carbonates and fluid migration on top of the Montepetra intrabasinal high (Northern Apennines, Italy): Relations with synsedimentary folding

“…Fluid expulsion at the sea floor is evidenced by: 1) specialized seep ecosystems (e.g., Sibuet and Olu, 1998;Van Dover et al, 2003), 2) authigenic carbonates (e.g., Aiello, 2005;Teichert et al, 2005;Campbell et al, 2008), 3) enhanced slope instability (Bohrmann et al, 2002), and 4) mud diapirs and volcanoes (Orange and Breen, 1992;Greinert et al, 2001;Kastner, 2001;Torres et al, 2002;Mazurenko and Soloviev, 2003;Moerz et al, 2005). Fluid emission along active continental margins could be located in erosive structures, such as canyons, head zones and scars of slides and slumpings (Duperret et al, 1995;Von Rad et al, 2000;Majima et al, 2005), or on relatively elevated structures, such as diapir-related mounds and mud volcanoes (Lance et al, 1998;Aloisi et al, 2000;Kopf et al, 2001;Mazurenko et al, 2002;Han et al, 2004), and at the top of anticlines and fault-controlled ridges (Lallemand et al, 1992;Suess et al, 1998Suess et al, , 1999Orphan et al, 2004).…”

Tectonic framework of the mud mounds, associated BSRs and submarine landslides, offshore Nicaragua Pacific margin

“…Currently, there is no stratigraphic or palaeontological study available to precisely identify the source depth of the ascending materials. Moerz et al (2005) have calculated the source depth for the mound Culebra (the location of that mound with respect to the study area is shown in Fig. 1) following a model of isostatic compensation, which relates the maximum height of a mud mound edifice to the thickness of the sediments overlying the mud source (Murton & Biggs 2003).…”

“…Gravity cores taken from some of these mounds revealed that they are constructed of soft mud, mud breccia with clasts, scaly clay and patches of carbonate crust (Sahling et al 2003;Moerz et al 2005;Schmidt et al 2005). Sea-floor observations by OFOS (ocean-floor observation system) video sled during R.V.…”

Seep-carbonates in a thrust-related anticline at the leading edge of an orogenic wedge: The case of the middle–late Miocene Salsomaggiore Ridge (Northern Apennines, Italy)

“…Vent sites are located in erosive structures, such as canyons (Von Rad et al, 2000;Majima et al, 2005), slide scars and slumpings (Duperret et al, 1995;Kahn et al, 1996) or on relatively elevated structures, such as mound diapirs and mud volcanoes, often fuelled by gas-hydrate dissociation (Lance et al, 1998;Aloisi et al, 2000;Kopf et al, 2001;Mazurenko et al, 2002;Han et al, 2004), anticlines (Orphan et al, 2004) structural highs and fault-controlled ridges (Lallemand et al, 1992;Suess et al, 1998Suess et al, , 1999Tréhu et al, 1999). Seepage systems are evidenced by authigenic carbonates, barite deposits, and complex sediment instability features, including soft-sediment deformation and diapiric breccias, (Orange and Breen, 1992;Greinert et al, 2001;Hyndman et al, 2001;Kastner, 2001;Torres et al, 2002;Mazurenko and Soloviev, 2003;Moertz et al, 2005).…”