Structural geometry and evolution of an intracratonic strike-slip fault zone: A case study from the north SB5 fault zone in the Tarim Basin, China

doi:10.1016/j.jsg.2020.104159

Journal of Structural Geology

Volume 140, November 2020, 104159

https://doi.org/10.1016/j.jsg.2020.104159 Get rights and content

Highlights

•
The NSB5FZ is a right-lateral strike-slip fault zone with a varying slip azimuth.
•
The structural deformation was affected severely by the pre-existing structures.
•
The NSB5FZ experienced three strike-slip movements during the early Paleozoic.

Abstract

The north SB5 fault zone (NSB5FZ) in the Tarim Basin experienced a multistage tectonic evolution, thereby displaying complex structural features. Three-dimensional seismic data were utilized to document the structural geometry and evolution of the fault zone. Comprehensive analysis of the seismic data suggests that the NSB5FZ is a strike-slip fault zone, and it slipped right-laterally during the early Paleozoic with a varying slip azimuth. Three different types of responses of the late structural deformation to the pre-existing structures exist on the NSB5FZ in its evolution. During the early Paleozoic, the NSB5FZ has experienced at least three strike-slip movements. (1) Induced by the first strike-slip movement, the lower-middle Cambrian strata were folded, and positive flower structures occurred. (2) During the second strike-slip movement period, several faults were produced and arranged both left- and right-stepping. The traces of these faults were right above the faults or anticline axes at depth. Sequentially, positive and negative relief occurred right above the left and right stepovers, respectively. (3) Induced by the third strike-slip movement, a series of en echelon normal faults developed above the NSB5FZ, while the contractional deformation in the stepovers at depth has not ceased but propagated upward.

Introduction

Fracture types and structural features associated with strike-slip movement have been characterized in detail in lots of literatures (e.g., Tchalenko, 1970; Christie-Blick and Biddle, 1985; Sylvester, 1988; Kelly et al., 1998; McClay and Bonora, 2001; Kim et al., 2003; Woodcock and Rickards, 2003; Waldron, 2005; Mitra and Paul, 2011; Dooley and Schreurs, 2012; Huang and Liu, 2017; Moscariello et al., 2018). In the recent years, the effect of pre-existing structures on the structural deformation caused by subsequent strike-slip movement has been paid more attention to (e.g., Hsiao et al., 2004; Cunningham and Mann, 2007; Ghosh and Chattopadhyay, 2008; Mitra and Paul, 2011; Dooley and Schreurs, 2012; Teng et al., 2016, 2019). In the same regional stress field, two distinctly different kinds of structures (including contractional and extensional structures) can occur simultaneously on one fault zone (e.g., Cunningham and Mann, 2007; Teng et al., 2016). When the pre-existing fault configuration consists of only one fault, if the slip direction is oblique to the orientation of the fault trace, transpression or transtension will develop (Fossen, 2010). The former is characterized by areas of positive relief (e.g., reverse faults, anticlines, etc), and the latter is represented by areas of negative relief (e.g., normal faults, extensional fractures, etc) (e.g., Imber et al., 2005; Robson et al., 2018). When the pre-existing fault configuration is composed of two adjacent faults, the fault arrangement includes left-and right-stepping (McClay and Bonora, 2001; Mitra and Paul, 2011). Left-lateral strike-slip movement can cause the strata in the left stepover to subside and the strata in the right stepover to be uplifted, whereas right-lateral strike-slip movement can cause the strata in the left stepover to be uplifted and the strata in the right stepover to subside (e.g., McClay and Bonora, 2001; Cembrano et al., 2005; Fossen, 2010; Mitra and Paul, 2011). The origin of the fault stepover (left-stepping or right-stepping) is well understood to be the segmented nature of a strike-slip fault (e.g., Cunningham and Mann, 2007; Carne and Little, 2012); however, the factors controlling such segmentation have seldom been discussed, especially for intracratonic strike-slip faults. On intracratonic strike-slip fault zones, the faults usually show the characteristics of strata-bound. The early-stage structural deformation may not be reactivated in the late stage, but the late-stage structural deformation is still influenced seriously by the occurrence of the pre-existing structures. As a result, up to date, few systematic studies have been carried out to discuss the structural evolution of an intracratonic strike-slip fault zone in a three-dimensional (3-D) space with full consideration of the influence of the pre-existing structures.

The Tarim Basin is the largest inland petroliferous basin in China, with reserves of approximately 6.8 × 10⁹ tons (oil equivalent) (Qi, 2016). Previous petroleum exploration was almost carried out on the thrust belts and the culminations of the uplifts (e.g., the south Tianshan folded belt, and the Tabei and Tazhong uplifts) (Fig. 1A), and a serious of large-scale oil and/or gas fields (e.g., the Kela-2 gas field, Tahe oil field, and the Tazhong oil and gas field) have been discovered (Jia and Li, 2008; Zhai and Yun, 2008; Han et al., 2012; Liu et al., 2013; Lu et al., 2017; Neng et al., 2018; Shen et al., 2019). Recently, a massive amount of petroleum was found in the area between the culminations of the Tabei and Tazhong uplifts, and almost all the commercial petroleum accumulations in this area occur on fault zones (Huang, 2014; Yun and Cao, 2014; Han et al., 2016; Qiu et al., 2017; Deng et al., 2018; Jiao, 2018), suggesting that the fault zones in the area between the culminations of the Tabei and Tazhong uplifts have excellent petroleum exploration prospects. Accordingly, several high-quality 3-D seismic data volumes covering the main fault zones in the area between the culminations of the Tabei and Tazhong uplifts were acquired by the Northwest Oilfield Branch Company (Sinopec) for further petroleum exploration. However, significant risks were previously considered to exist for petroleum exploration on the fault zones in the central Tarim Basin because of two main features: (1) The main fault zones in the central Tarim Basin experienced a multistage tectonic evolution, resulting in complex structural styles (Han et al., 2017). The development of two distinctly different kinds of structures (including contractional and extensional structures) coincided in time and space on a fault zone, the cause of which is difficult to understand. (2) The main fault zones in the central Tarim Basin are dominated by intracratonic strike-slip fault zones (Deng et al., 2019), on which the faults usually show the characteristics of strata-bound and the structural deformation in the upper strata is not only caused by the regional stress field but also affected severely by the pre-existing structures. These intracratonic strike-slip faults are commonly highly segmented, so that positive or negative relief can occur right above the stepovers, whereas the factors controlling such segmentation are not clear, thereby leading to difficulty in understanding the structural evolution of these faults.

The aim of this study is to take the north SB5 fault zone (NSB5FZ) in the Tarim Basin (Fig. 1) as an example and use 3-D seismic database to (1) characterize the geometry of the intracratonic strike-slip fault zone, (2) indicate the slip vector, (3) propose a possible factor that controls the fault segmentation, (4) document the response of the late structural deformation to the pre-existing structures, and (5) better understand the structural evolution of the fault zone.

Section snippets

Geologic setting

The Tarim Basin, located in the northwest of China, is the largest inland basin in China, with a total area of about 560,000 km² (Li et al., 1996; Lan et al., 2015). This basin displays a rhomboid-shaped geometry in map view and is bounded by the Tianshan folded belt to the northwest, the Jueluotage folded belt and Kuruktag fault-uplift zone to the northeast, the eastern Kunlun folded belt and Altyn Tagh fault-uplift zone to the southeast, and the western Kunlun folded belt and Tieke Lectra

Data and methods

The high-quality 3-D seismic data used in this study were provided by the Northwest Oilfield Branch Company (Sinopec). The data set, with an area of 25 × 11 km, is a rectangular survey and covers part of the NSB5FZ (Fig. 1B). The inlines and crosslines are north- and east-oriented, respectively, and both of them have a 25 m spacing. The dominant frequency in the Paleozoic strata is 20–25 Hz.

The stratigraphic horizons were marked by seismic reflecting surfaces, which were determined by

Structural geometry of the north SB5 fault zone

The SB5 fault zone is located in the central Tarim Basin (Fig. 1A). It shows a curvilinear trace in map view, with a length of approximately 265 km. To the north, it cuts into the Tabei uplift and terminates against the Luntai fault zone (Fig. 1B). The azimuth is about 345°, nearly consistent with the majority of the faults on the Tabei uplift. To the south, the SB5 fault zone bends clockwise and extends through the Shuntuo low uplift into the Tazhong uplift, with an azimuth of about 20° (Fig. 1

Deformational magnitude of the north SB5 fault zone

The horizontal displacement of the north SB5 fault on the T₇⁴ seismic surface has been measured by other scholars to be between 280 and 350 m (Deng et al., 2019). In this study, amplitudes of the vertical deformation and widths of the deformation zone of the T₇⁴ seismic surface across the fault zone were provided to characterize the deformational magnitude of the NSB5FZ (Fig. 9). Along strike of the NSB5FZ, amplitudes of the vertical deformation vary significantly (Fig. 9A). In the areas of

Strike-slip of the north SB5 fault zone

Structural geometry shown in plan and section views indicates that the NSB5FZ has fault features typical of a strike-slip fault system (cf. Christie-Blick and Biddle, 1985; Sylvester, 1988), including in plan view, (1) the main fault with relatively straight fault trace (Fig. 4A–C) and (2) en echelon small-scale faults developing above the main fault (Fig. 4D), and in section view, (3) the main fault with a subvertical dip angle (Fig. 6, Fig. 7, Fig. 8) and (4) flower structures (Fig. 6, Fig. 7

Conclusions

The NSB5FZ in the central Tarim Basin has experienced a multistage tectonic evolution, thereby displaying complex structural styles. Based on our study, the following conclusions can be drawn.

(1)
The NSB5FZ is a strike-slip fault zone, and it slipped right-laterally during the early Paleozoic. The azimuth of the strike-slip was approximately 340° before the late stage of the late Ordovician, and was smaller than 335.5° during the period from the late stage of the late Ordovician to the Silurian.

CRediT authorship contribution statement

Changyu Teng: Conceptualization, Methodology, Writing - original draft. Zhongxian Cai: Supervision, Writing - review & editing. Fang Hao: Supervision, Writing - review & editing. Zicheng Cao: Data curation, Writing - review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, China (XDA14010302) . We thank the Exploration and Production Research Institute of Northwest Oilfield Branch Company, Sinopec, for kindly providing part of the data in this study. Dr. C Passchier (Editor) and an anonymous reviewer are gratefully acknowledged for their thorough and critical reviews and suggestions to improve the manuscript.

References (66)

J. Cembrano et al.
Fault zone development and strain partitioning in an extensional strike-slip duplex: a case study from the Mesozoic Atacama fault system, Northern Chile
Tectonophysics
(2005)
C.M. Chen et al.
Closing history of the southern Tianshan oceanic basin, western China: an oblique collisional orogeny
Tectonophysics
(1999)
T.P. Dooley et al.
Analogue modelling of intraplate strike-slip tectonics: a review and new experimental results
Tectonophysics
(2012)
X.Y. Han et al.
Geometry, kinematics and displacement characteristics of strike-slip faults in the northern slope of Tazhong uplift in Tarim Basin: a study based on 3D seismic data
Mar. Petrol. Geol.
(2017)
B.Z. He et al.
The paleotectonic and paleogeography reconstructions of the Tarim Basin and its adjacent areas (NW China) during the late Early and Middle Paleozoic
Gondwana Res.
(2016)
P.G. Kelly et al.
Linkage and evolution of conjugate strike-slip fault zones in limestones of Somerset and Northumbria
J. Struct. Geol.
(1998)
Y. Kim et al.
Mesoscale strike-slip faults and damage zones at Marsalforn, Gozo Island, Malta
J. Struct. Geol.
(2003)
X.D. Lan et al.
The geometry and origin of strike-slip faults cutting the Tazhong low rise megaanticline (central uplift, Tarim Basin, China) and their control on hydrocarbon distribution in carbonate reservoirs
J. Nat. Gas Sci. Eng.
(2015)
C.X. Li et al.
Paleozoic fault systems of the Tazhong uplift, Tarim basin, China
Mar. Petrol. Geol.
(2013)
Y.J. Li et al.
Cenozoic faults and faulting phases in the western Tarim Basin (NW China): effects of the collisions on the southern margin of the Eurasian Plate
J. Asian Earth Sci.
(2016)

Z. Li et al.

Precambrian evolution of the Tarim Block and its tectonic affinity to other major continental blocks in China: new clues from U-Pb geochronology and Lu-Hf isotopes of detrital zircons

Precambrian Res.

(2015)

Z.L. Li et al.

Temporal evolution of the Permian large igneous province in Tarim Basin in northwestern China

J. Asian Earth Sci.

(2011)

C.S. Lin et al.

Distribution and erosion of the Paleozoic tectonic unconformities in the Tarim Basin, Northwest China: significance for the evolution of paleo-uplifts and tectonic geography during deformation

J. Asian Earth Sci.

(2012)

K.Y. Liu et al.

Hydrocarbon charge history of the Tazhong Ordovician reservoirs, Tarim Basin as revealed from an integrated fluid inclusion study

Petrol. Explor. Dev.

(2013)

X.B. Lu et al.

New insights into the carbonate karstic fault system and reservoir formation in the Southern Tahe area of the Tarim Basin

Mar. Petrol. Geol.

(2017)

F. Mattern et al.

Suturing of the proto- and paleo-tethys oceans in the western Kunlun (xinjiang, China)

J. Asian Earth Sci.

(2000)

A. Moscariello et al.

Genesis and evolution of the watukosek fault system in the lusi area (east java)

Mar. Petrol. Geol.

(2018)

Y. Neng et al.

Structural patterns of fault damage zones in carbonate rocks and their influences on petroleum accumulation in Tazhong Paleo-uplift, Tarim Basin, NW China

Petrol. Explor. Dev.

(2018)

A.G. Robson et al.

Structural evolution of horst and half-graben structures proximal to a transtensional fault system determined using 3D seismic data from the Shipwreck Trough, offshore Otway Basin, Australia

Mar. Petrol. Geol.

(2018)

R. Sharps et al.

Lower Permian paleomagnetism of the Tarim block, northwestern China

Earth Planet Sci. Lett.

(1989)

W.B. Shen et al.

The origin, migration and accumulation of the Ordovician gas in the Tazhong III region, Tarim Basin, NW China

Mar. Petrol. Geol.

(2019)

L.J. Tang et al.

Poly-phase reform-late-stage finalization composite tectonics and strategic area selection of oil and gas resources in Tarim Basin, NW China

J. Jilin Univ. (Earth Sci. Ed.)

(2014)

C.Y. Teng et al.

Tectonic evolution of the Penglai 7-6 structure and its implications for petroleum exploration in a releasing bend of a strike-slip fault system, Tan-Lu fault zone, east China

Mar. Petrol. Geol.

(2019)

J.W.F. Waldron

Extensional fault arrays in strike-slip and transtension

J. Struct. Geol.

(2005)

N.H. Woodcock et al.

Transpressive duplex and flower structure: dent fault system, NW england

J. Struct. Geol.

(2003)

Z.Q. Xu et al.

Tectonic framework and crustal evolution of the Precambrian basement of the Tarim Block in NW China: new geochronological evidence from deep drilling samples

Precambrian Res.

(2013)

C.L. Zhang et al.

Tectonic framework and evolution of the Tarim block in NW China

Gondwana Res.

(2013)

R.C. Carne et al.

Geometry and scale of fault segmentation and deformational bulging along an active oblique-slip fault (Wairarapa fault, New Zealand)

GSA Bull

(2012)

H.L. Chen et al.

Sedimentary response to the Early-Mid Permian basaltic magmatism in the Tarim plate

Chin. Geol.

(2006)

N. Christie-Blick et al.

Deformation and basin formation along strike-slip faults

The Society of Economic Paleontologists and Mineralogists

(1985)

W.D. Cunningham et al.

Tectonics of strike-slip restraining and releasing bends

Geol. Soc. Lond. Spec. Publ.

(2007)

S. Deng et al.

Characteristics of differential activities in major strike-slip fault zones and their control on hydrocarbon enrichment in Shunbei area and its surroundings, Tarim Basin

Oil Gas Geol.

(2018)

S. Deng et al.

Structural characterization of intracratonic strike-slip faults in the central Tarim Basin

AAPG Bull.

(2019)

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Structural geometry and evolution of an intracratonic strike-slip fault zone: A case study from the north SB5 fault zone in the Tarim Basin, China

Highlights

Abstract

Introduction

Section snippets

Geologic setting

Data and methods

Structural geometry of the north SB5 fault zone

Deformational magnitude of the north SB5 fault zone

Strike-slip of the north SB5 fault zone

Conclusions

CRediT authorship contribution statement

Declaration of competing interest

Acknowledgments

Tectonophysics

Tectonophysics

Tectonophysics

Mar. Petrol. Geol.

Gondwana Res.

J. Struct. Geol.

J. Struct. Geol.

J. Nat. Gas Sci. Eng.

Mar. Petrol. Geol.

J. Asian Earth Sci.

Precambrian Res.

J. Asian Earth Sci.

J. Asian Earth Sci.

Petrol. Explor. Dev.

Mar. Petrol. Geol.

J. Asian Earth Sci.

Mar. Petrol. Geol.

Petrol. Explor. Dev.

Mar. Petrol. Geol.

Earth Planet Sci. Lett.

Mar. Petrol. Geol.

J. Jilin Univ. (Earth Sci. Ed.)

Mar. Petrol. Geol.

J. Struct. Geol.

J. Struct. Geol.

Precambrian Res.

Gondwana Res.

Geometry and scale of fault segmentation and deformational bulging along an active oblique-slip fault (Wairarapa fault, New Zealand)

GSA Bull

Sedimentary response to the Early-Mid Permian basaltic magmatism in the Tarim plate

Chin. Geol.

Deformation and basin formation along strike-slip faults

The Society of Economic Paleontologists and Mineralogists

Tectonics of strike-slip restraining and releasing bends

Geol. Soc. Lond. Spec. Publ.

Characteristics of differential activities in major strike-slip fault zones and their control on hydrocarbon enrichment in Shunbei area and its surroundings, Tarim Basin

Oil Gas Geol.

Structural characterization of intracratonic strike-slip faults in the central Tarim Basin

AAPG Bull.