Tectonic Characteristics of the Juyanhai Depression in the Yingen-Ejinaqi Basin, Inner Mongolia, China, Based on Gravity, Electrical, and Seismic Data

TL;DR

This paper analyzes the tectonic features of the Juyanhai Depression in China using geophysical data to guide resource exploration.

Contribution

The study identifies fault systems and structural patterns in the Juyanhai Depression to inform resource exploration strategies.

Findings

Three main fault groups control sedimentary thickness and local structures in the Juyanhai Depression.

The depression contains 13 primary structures, including arches and sags, with distinct tectonic characteristics.

Resource exploration should focus on sags, with different targets in shallow and deep parts.

Abstract

To determine the
tectonic characteristics of the Juyanhai Depression
in the west of the Yingen-Ejinaqi Basin, gravity data in the study
area were processed and analyzed on the basis of the collection of
existing geophysical data. Then, fault systems in the Juyanhai Depression
were comprehensively presumed and explained mainly using processed
gravity data in conjunction with the electrical and seismic data.
Existing tectonic units in the depression were divided and studied
afterward. There are mainly three groups of faults in the Juyanhai
Depression, namely, the NE (or NNE)-, NW (or NWW)-, and nearly EW-trending
ones. Faults not only control the thickness difference of sedimentary
strata on both sides but also play an important role in controlling
the formation of local structures and hydrocarbon accumulation. The
Juyanhai Depression can be categorized into 13 primary structures,
including six arches and seven sags. The sags and arches are independent,
separated, and distributed in rows along the NE (or NNE) trend on
the whole. According to structural patterns, sags can be classified
into single-fault and double-fault ones. The characteristics of single-fault
sags are that their formation is controlled by the main controlling
normal faults of boundaries, manifested as half-graben fault depressions.
The characteristics of double-fault sags are that their formation
is controlled by the normal faults on both sides, while the fault
distance of the sag-controlling faults differs on both sides. The
research region has good prospects for a variety of resources, including
oil and gas, shale oil and gas, coal, and uranium, and the distribution
of these resources is closely related to the range of tectonic units.
Therein, oil–gas exploration should mainly focus on sags. In
the shallow part of the sags, fault-anticlines, fault blocks, fault-screened
traps, and lithologic oil–gas reservoirs in the slopes should
be the main targets of exploration. In the deep part of the sags,
the bedrock buried hill reservoirs and the igneous rock lateral-screened
oil–gas reservoirs formed by igneous intrusions are favorable
exploration targets.

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