Identification of hydrovolcanism and its significance for hydrocarbon reservoir assessment: A review

Xian, Ben-Zhong; He, Yan-Xin; Niu, Hua-Peng; Wang, Jun-Hui; Liu, Jian-Ping; Wang, Zhen

doi:10.1186/s42501-018-0010-6

Journal of Palaeogeography

Table 2 Reliability and potential risks of the identification marks of hydrovolcanism

From: Identification of hydrovolcanism and its significance for hydrocarbon reservoir assessment: A review

Identification marks				Direct marks	Degree of reliability	Potential risks
Eruptive products	Microtextures	Quenching cracks		No	*****	Destroyed by diagenesis Destroyed by later thermodynamic contact metamorphism
		Bread-crusted structure		No	****
		Stepped fractures		No	****
		Cracks through particles		No	**
		Perlitic texture		No	**
		Grain size and its parameters		No	****
		Roundness		No	**
		Quenching texture		No	*****
		Cementation type		No	**
		Vesicularity		Yes	*****	Only applied to explosive eruption identification
		Chilled margin		No	**	Also developed in margins of ultra-shallow intrusive rocks Also developed in lava surface layer formed in subaerial eruption
	Special structures	Graded structures		No	*	Also exist when volcanic materials were transported Turbidity deposits: Also could develop small-scale graded beddings Hydraulic jump: Also could develop antidune beddings, water and wind beddings
		Large-scale cross-beddings		No	*****
		Pillow structures		No	*****	Only applied to lava in effusive facies Also formed when the subaerial magma flows into river Note to distinguish from non-radial joints and vacant spherical weathering
	Lithofacies and facies sequences	Lithofacies	Perlite	No	**	Also formed in intrusive body under water-rich environment
			Peperite	No	*****
			Spilite	No	***	Origin is controversial
		Facies sequences	Effusive	No	*****
		Facies sequences	Explosive	No	****	Hard to be applied alone
	Oxidation index			No	****	Magma content can affect the oxidation index Secondary changes of volcanic rocks such as the late weathering Note the oxidation in the test experiment
Associated environment	Overlying sedimentary environment			No	*****	The following two conditions need to be cautiously applied: (1) Large-scale scouring in the bottom and depositional breaks occur; (2) Being exposed after hydrovolcanism, weathering and/or erosion
Associated environment	Underlying sedimentary environment			No	****

The quantities of * means the degree of reliability; the highest degree of reliability is shown as *****, and the lowest is shown as *

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