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\DOI{10.5802/crgeos.245}
\datereceived{2023-05-14}
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\dateposted{2023-12-21}
\begin{document}

\begin{noXML}



\title{Lithospheric reworking and thinning by cyclical continental
extension: a synthesis of Cretaceous extensional domes in the South
China Block}

\alttitle{Remaniement et amincissement de la lithosph\`{e}re par
extension continentale cyclique : Une synth\`{e}se des d\^{o}mes
extensifs d'\^{a}ge Cr\'{e}tac\'{e} dans le bloc de Chine
m\'{e}ridionale}

\author{\firstname{Yang} \lastname{Chu}\CDRorcid{0000-0003-3253-9599}\IsCorresp}
\address{State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geophysics, Institutions of Earth Science, Chinese Academy
of Sciences, Beijing, China}
\address{University of Chinese Academy of Sciences, Beijing, China}
\email[Y. Chu]{chuyang@mail.iggcas.ac.cn}

\author{\firstname{Tanjie} \lastname{Liu}}
\addressSameAs{1}{State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geophysics, Institutions of Earth Science, Chinese Academy
of Sciences, Beijing, China}
\addressSameAs{2}{University of Chinese Academy of Sciences, Beijing, China}

\author{\firstname{Wei} \lastname{Lin}\CDRorcid{0000-0001-8966-5399}}
\addressSameAs{1}{State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geophysics, Institutions of Earth Science, Chinese Academy
of Sciences, Beijing, China}
\addressSameAs{2}{University of Chinese Academy of Sciences, Beijing, China}

\author{\firstname{Lingtong} \lastname{Meng}}
\addressSameAs{1}{State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geophysics, Institutions of Earth Science, Chinese Academy
of Sciences, Beijing, China}
\addressSameAs{2}{University of Chinese Academy of Sciences, Beijing, China}

\author{\firstname{Zhentian} \lastname{Feng}}
\address{Shandong Provincial Research Institute of Coal Geology Planning and Exploration, Jinan, China}

\author{\firstname{Wei} \lastname{Wei}}
\addressSameAs{1}{State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geophysics, Institutions of Earth Science, Chinese Academy
of Sciences, Beijing, China}
\addressSameAs{2}{University of Chinese Academy of Sciences, Beijing, China}

\author{\firstname{Wenbin} \lastname{Ji}\CDRorcid{0000-0003-0968-3680}}
\address{State Key Laboratory of Continental Dynamics, Department of
Geology, Northwest University, Xi'an, China}

\author{\firstname{Zhenhua} \lastname{Xue}\CDRorcid{0000-0002-3328-2740}}
\address{School of Earth Sciences, China University of Geosciences,
Wuhan, China}

\shortrunauthors

\thanks{This project has received funding from the National Science
Foundation of China (Grant Numbers: U2344213 and 41872208),  the State
Key Laboratory of Lithospheric Evolution (Grant Number:  SKL-Z202205),
the Key Research Program of the Institute of Geology  and Geophysics,
Chinese Academy of Sciences (Grant Number: IGGCAS-202204),  and the
Youth Innovation Promotion Association (Grant Number: 2019065).}

\begin{abstract}
Continents with cratonic cores can resist deformation, and thus survive
billions of years in the geological record. Tectonic reworking is a
significant process that weakens and destructs cratons, but our
understanding of the process remains incomplete. In the South China
Block, Mesozoic cyclical tectonics destructed a large portion of its
cratonic lithosphere. Here, we synthesized the structural evolution of
extensional domes and illustrated the process of lithospheric thinning.
Unlike the previous rapid, one-cycle delamination model, we propose a
new model that multicycle compression and extension progressively
destructed the lithosphere, which reconciles both surface geology and
deep process.
\end{abstract}

\begin{altabstract}
Les continents dot\'{e}s d'un noyau cratonique peuvent r\'{e}sister
\`{a} la d\'{e}formation et survivre ainsi des milliards d'ann\'{e}es
dans les archives g\'{e}ologiques. Le remaniement tectonique est un
processus important qui affaiblit et d\'{e}truit les cratons, mais
notre compr\'{e}hension de ce processus reste incompl\`{e}te. Dans le
bloc de Chine m\'{e}ridionale, la tectonique m\'{e}sozo\"{i}que est
repr\'{e}sent\'{e}e par des cycles d'e compression et d'extension. Elle
a d\'{e}truit une grande partie de la lithosph\`{e}re cratonique. Cet
article synth\'{e}tise l'\'{e}volution structurale des d\^{o}mes
extensifs et illustre le processus d'amincissement de la
lithosph\`{e}re. Contrairement au mod\`{e}le pr\'{e}c\'{e}dent de
d\'{e}lamination rapide \`{a} un cycle, nous proposons ici un nouveau
mod\`{e}le selon lequel la compression et l'extension au cours de
plusieurs cycles ont progressivement d\'{e}truit la lithosph\`{e}re. Ce
mod\`{e}le r\'{e}concilie \`{a} la fois la g\'{e}ologie de surface et
les processus profonds.
\end{altabstract}

\keywords{\kwd{Continental reworking}
\kwd{Lithospheric thinning}
\kwd{Extensional domes}
\kwd{Cretaceous}
\kwd{Cyclical tectonics}
\kwd{South China}}

\altkeywords{\kwd{Remaniement continental}
\kwd{Amincissement lithosph\'{e}rique}
\kwd{D\^{o}mes extensifs}
\kwd{Cr\'{e}tac\'{e}}
\kwd{Tectonique cyclique}
\kwd{Chine du Sud}}

\maketitle

\clearpage

\twocolumngrid

\end{noXML}

\section{Introduction}\label{sec1}

{\advance\baselineskip-.3pt
Continents with thick, rigid lithosphere are called cratons. They can
survive destruction of multiple tectonic events for the last 2 billion
years \citep{Leeetal2011}, while some of them have been destructed and
lost their stability \citep{Zhuetal2021}. Tectono-thermal reworking is a
key process in continental evolution because it alters composition and
structure of some continents, weakens, and finally destructs or even
dismembers them \citep{Holdsworthetal2001}. Typical examples of
reworked continents develop in subduction or collision settings, mostly
situating in East Asia, Western North America, or the Tethyan
\mbox{collisional} zones \citep{Baoetal2015,YonkeeWeil2015,Zhuetal2021}.
In western Pacific, East Asian continental margins suffered
extensive continental reworking and lost part of their continental
lithosphere and developed a wide (${>}$1000~km) extensional province
\citep{Chenetal2008,Zhuetal2011,Chuetal2019,LinWei2020,Dengetal2021}. 
Mesozoic is an important era for the reworking, because the
Paleo-Pacific subduction initiated and caused voluminous magmatism and
cyclical contractional-extensional deformation that extensively
deformed the continent through the entire era \citep{LiLi2007}. Such a
strongly modified continent represents an ideal target to reveal the
process and mechanism of continental reworking.

As two major constituents of East Asia, the South China Block (SCB) and
the North China Craton (NCC) both experienced Mesozoic tectonic
reworking and lithospheric destruction after their Proterozoic
cratonization
\citep{Wangetal2013b,Lietal2014,Chuetal2019,Wuetal2019,LinWei2020}. 
However, they show distinct surface geology and deformation patterns.
The reworking of the NCC produced widespread Early Cretaceous extension
that destructed and delaminated ${\sim}$100~km thick continental
lithosphere of the eastern craton \citep{Wuetal2019}. This lithospheric
delamination model is also referred to as cratonic destruction 
\citep{Zhuetal2011}. In contrast, Mesozoic tectonic events changing the
lithosphere structure of the SCB reflect episodic compression--extension
and magmatic flare-up and lull intervals 
\citep{Zhouetal2006,Lietal2014,Chuetal2019}. The timing and mode of
lithospheric loss are less discussed and thus remain controversial. 

From Triassic to Cretaceous, the SCB recorded at least three stages of
compressional tectonics, Early to Middle Triassic, Late Jurassic, and
late Early Cretaceous
\citep{Zhangetal2012,Lietal2014,Shuetal2015,Faureetal2016,Chuetal2019}.
Following each of these compressional events, Early Jurassic, Early
Cretaceous, and Late Cretaceous crustal extension, and magmatic
flare-ups greatly reshaped these early compressional thrust belts
covering almost the whole SCB. Although these events were slightly
diachronous and unevenly developed between inland and coastal regions,
the latter two stages of extension, Early Cretaceous and Late
Cretaceous, are well manifested by extensional domes 
\citep{Linetal2000,Zhuetal2010a,Zhuetal2010b,Weietal2016,Chuetal2019,Lietal2020}. The
tectonic cyclicity characterizes the reworking process of the SCB and
itself displays an uncommon mechanism of continental reworking.
Structural work on different regions of the SCB has been well
documented, but reconstructing the reworking process requires a
comprehensive view of all extensional domes and comparison on the
structural patterns and detachment evolution. In this review, we
synthesize the Late Mesozoic extensional domes that document the main
continental extension stages, and analyze the features of detachments,
including structural patterns, detachment strain rates, and regional
tectonic histories. Finally, we discuss the controlling factors of the
heterogeneous extension, lithospheric removal, and geodynamics of this
cyclical extension, and propose a new model of continental reworking
distinct from the cratonic destruction model of the NCB and the Western
North America.}

\section{Tectonic divisions and history of South China}\label{sec2}

\begin{figure*}
\includegraphics[width=0.92\textwidth]{fig01_new}
\vspace*{-2pt}
\caption{Tectonic map of the South China Block and adjacent regions
\citep[modified after][]{Chuetal2019}. Mesozoic structures including
fold--thrust belts and major extensional domes are highlighted on
this map. JSF: Jiangshan-Shaoxing Fault. CLF: Chenzhou-Linwu Fault.
ZDF: Zhenghe--Dapu Fault. Extensional domes: DYS: Dayunshan. HL:
Huangling. HS: Hengshan. HZ: Hongzhen. LHS: Lianhuashan. LS: Lushan.
WGS: Wugongshan. YCL: Yuechengling.\label{fig1}\vspace*{-2pt}}
\end{figure*}

The SCB consists of two subdivisions, the Yangtze Craton to the west
and the Cathaysia Block to the east, but the cratonic lithosphere of
the Yangtze Craton is only preserved beneath the Sichuan Basin that is
bounded by orogenic belts with basin-vergent thrust belts, including
the Dabashan, Longmenshan, Sanjiang Belt, and East Sichuan-Xuefengshan
Belts (Figure~\ref{fig1}). Except the long-lasting (Paleo-) Pacific
subduction system at the eastern margin, the peripheral domains of the
SCB are Triassic belts. To the west and southwest, they resulted from
the closure of the Paleotethys and collision with the Qiangtang, and
Indochina Blocks, while the Qinling-Dabie-Sulu belt to the north was
formed by convergence between the SCB and NCB (Figure~\ref{fig1}). 

The Jiangnan collisional belt records the Neoproterozoic amalgamation
of the SCB  \citep{Charvetetal1996,ShuCharvet1996}. The northeastern
segment of the suture zone, the Jiangshan-Shaoxing Fault, consists of
well-preserved arc and high-pressure metamorphic rock assemblages
\citep{Lietal2009}, while the southwestern segment vanishing under the
Paleozoic to Mesozoic sedimentary cover is represented by the
Chenzhou-Linwu Fault \citep{Zhangetal2013}.
This ancient suture zone
serves as an important weak zone and is repeatedly reactivated by later
tectonic events.


Early Paleozoic intracontinental orogeny involved almost half area of
the SCB, lasted for over \mbox{80 million} years (Myr), and greatly reworked
the Cathaysia Block by high-grade metamorphism, middle-high temperature
double-vergent ductile shearing, and syn- and post-orogenic magmatism
\citep{Linetal2008,Lietal2010,Wangetal2013b,Fengetal2022b}. This orogeny
is interpreted as bivergent compressional tectonics stemmed from the
Neoproterozoic suture zone
\citep{Faureetal2009,Charvetetal2010,ChuLin2014}.

\begin{figure*}
\includegraphics{fig02}
\caption{Age compilation of structural, igneous and volcanic events
\citep[modified from][]{Chuetal2019}.\label{fig2}}
\end{figure*}

The dominant NE--SW trending structural lines in most of the SCB was
formed by the Mesozoic-to-present (Paleo-) Pacific subduction system
\citep{ZhouandLi2000,LiLi2007}. Except the rigid Sichuan Basin,
mountainous regions cover the entire SCB from its SE continental margin
to its interior \mbox{(Figure~\ref{fig1})}. At its southeast are the
East-Sichuan Belt and Xuefengshan Belt that share a similar deformed
pattern but have different tectonic stages. The East-Sichuan belt
formed in Jurassic to Cretaceous \citep{Yanetal2003}, whereas the
Xuefengshan-Jiuling Belt rose during the Triassic to Jurassic
compression. Both belts stemmed from the reworking along the ancient
Neoproterozoic suture zone to the east \citep{Chuetal2012,ChuLin2014}.
The Xuefengshan-Jiuling Belt represents an important tectonic boundary,
east of which Cretaceous extensional structures and magmatism are
widespread. The southeastern Yangtze Craton and the entire Cathaysia
block shared similar tectonic and magmatic history, except the coastal
Cathaysia covered by Early Cretaceous volcanic rocks \citep{LiLi2007}.
In the following, we shall consider the SCB with a rigid core and a
reworked unit divided by the Xuefengshan-Jiuling Belt for further
discussing the Mesozoic tectonic evolution.

During the Late Jurassic, the SCB underwent the most abundant magmatism,
but record of extensional deformation is weak \citep{Zhouetal2006}.
Most plutons have a rounded cartographic shape. Some plutons show weak
syn-magmatic extension during the magma emplacement 
\citep{Weietal2016,Jietal2018a,Jietal2018b}. As key
indicators for lithospheric thinning or destruction, Cretaceous
magmatic flare-ups occurred in two stages (Figure~\ref{fig2})
\citep{ZhouandLi2000,Li2000,Lietal2014,Chuetal2019}. Extensional structures,
including extensional domes/metamorphic core complexes and normal
fault-controlled basins, prevailed in the two stages of Late Mesozoic
and gave rise to large normal faults or detachments
\citep{Shuetal2009}. These low-angle normal faults or detachments
therefore provide a window to reveal a detailed extensional process and
interaction between intracontinental extension and plate margin
tectonics. 

\section{Deformation of extensional domes with detachment}\label{sec3}

In this section, we review several recent structural studies on major
Cretaceous extensional domes in South China. Here, because the
detachments and structural geometry of extensional domes are different
from the classic model of MCC in western America which has curved
detachment plane and breakaway faults, we prefer to use extensional
dome instead of MCC to define all the Cretaceous extensional
structures. These extensional domes, from interior to coastal regions,
are Yuechengling, Huangling, Hengshan, Dayunshan, Wugongshan, Lushan,
Hongzhen, Lianhuashan (Figure~\ref{fig1}). They characterize the Late
Mesozoic South China extensional province. It is noteworthy that in
some domes, a few muscovite ages are younger than that of biotite, and
our preferred interpretation is that the muscovite
$^{40}$Ar--$^{39}$Ar system may have been disturbed by later
fluid-assisted dissolution or deformation. In this work, we only use
$^{40}$Ar--$^{39}$Ar ages from the same mineral (biotite or muscovite)
to retrieve the rates of different domes
\citep{Fosteretal2010}. This can avoid the age
discrepancy and closure temperature difference between biotite and
muscovite.

\subsection{Yuechengling}\label{sec31}

\subsubsection{Deformation pattern}\label{sec311}

\begin{figure*}
\vspace*{3pt}
\includegraphics{fig03}
\vspace*{3pt}
\caption{Geological map (a), map with published ages (b), and
cross-section (c) of the Yuechengling dome 
\citep[modified from][]{Chuetal2019}.
ZYD: Ziyuan Detachment. THF: Tianhu Fault.
\label{fig3}}
\vspace*{3pt}
\end{figure*}

The Yuechengling dome is located in the Xuefengshan Belt and is the
westernmost extensional dome of South China. It consists of
Neoproterozoic to Triassic sedimentary rocks, the
Yuechengling--Miaoershan pluton, and Cretaceous red beds. The age of
the Yuechengling-Miaoershan biotite granite/monzogranite varies from
420~Ma to 380~Ma, and some small dikes or stocks intruded into the main
pluton during the Triassic and Jurassic
\citep{Zhou2007,Chuetal2012,Zhaoetal2013}. The main {detachment}
controlling the Yuechengling extensional dome is the Ziyuan Detachement
(Figure~\ref{fig3}) developed between the Miaoershan and Yuechengling
plutons. Another ductile normal fault, the Tianhu Fault, separates the
Yuechengling Pluton into the strongly deformed western Yuechengling
Pluton and weakly to non-deformed eastern Yuechengling Pluton
\citep{Chengetal2016,Chuetal2019,Fengetal2022a}. \looseness=1

The Yuechengling Pluton and Neoproterozic-Early Paleozoic metasediments
comprise the footwall of the Ziyuan Detachment. This detachment
deformed a ${\sim}$10--15~km-wide proto-mylonitic to mylonitic zone in
the western Yuechengling Pluton. The deformed zone is ${\sim}$15~km wide
in the middle and shrinks towards the north and south. This detachment
shows a shallow dip angle of ${\sim}$20--30\textdegree, top-to-the W
shear sense, and a complete faulted rock sequence with tectonic
breccia, cataclasite, mylonite, and gneissic granite
(Figure~\ref{fig3}c). The deformation temperature varies between the
two ductile faults, in which the Ziyuan Detachment records a high
temperature at ${\sim}$500~\textdegree C and the Tianhu Fault deforms the
rocks at ${\sim}$300~\textdegree C \citep{Chuetal2019}.

In the hanging wall, the Miaoershan Pluton and the Xinning Basin are
undeformed, but brittle faults and joints related to the detachment can
be observed \citep{Chuetal2019}. The sedimentary sequence of the
Xinning basin starts with poorly sorted breccia and gradually changes
to coarse grain sandstone with a major component from the exposed
Yuechengling granite and Paleozoic rocks. The tilted strata and
conjugate joints by E--W extension indicate that the Xinning basin
formed during the development of the Yuechengling dome
\citep{BGMRGX1985,Chuetal2019}.

\subsubsection{Timing of deformation}\label{sec312}

The Yuechengling dome has the best record of the Cretaceous two-staged
extension of the SCB. The Early Cretaceous extension is localized in
the high-angle brittle--ductile Tianhu Fault. $^{40}$Ar--$^{39}$Ar
cooling ages suggests that the fault was active at 140--120~Ma and
continuous tectonic uplifting of the eastern Yuechengling Pluton
\citep{Chuetal2019}. Whether the main Ziyuan Detachment was also active
in Early Cretaceous remains elusive, because it lacks early cooling
ages and the initial age of syn-extensional basin sequence is still
undetermined. The Late Cretaceous extension resulted in the final
exhumation of the Yuechenling dome, while the Ziyuan Detachment played
a dominant role in strain accumulation, rock deformation and tectonic
uplifting. Detailed age constraints demonstrate an increasing age trend
dependent on the distance to the detachment, which rapidly cooled at
99--87~Ma (Figure~\ref{fig3}). The early stage has a slow slip rate at
0.05~mm/y (millimeter per year), while the rate is 10 times higher at
0.5~mm/y for the Late Cretaceous detachment activity\break
(Figure~\ref{fig4}).

\begin{figure}
{\vspace*{3pt}}
\includegraphics{fig04}
\caption{Sample ages plotted against fault-perpendicular distance from
the Ziyuan Detachment. Age information and references are listed in
Supplementary Table S1. The dashed lines are calculated in Excel by
generating a trendline and a function of it. The slip rate is the slope
of  trendlines.\label{fig4}}
\end{figure}

\subsection{Hengshan}\label{sec32}

\subsubsection{Deformation pattern}\label{sec321}

The Hengshan dome is located in the center of the SCB and adjacent to
the Neoproterozoic suture zone (Figure~\ref{fig1}). This extensional
structure is bounded by a lengthy normal fault that controlled
evolution of the Hengyang basin. The dome consists of a composite
pluton intruding low-grade Neoproterozoic metasediments, and a large
Early Cretaceous red-bed basin (Figure~\ref{fig5}a). In the composite
pluton, the east Nanyue pluton yields a Triassic age at ${\sim}$230~Ma,
while the west Baishifeng pluton crystallized in Early Cretaceous,
around 150~Ma \citep{Lietal2013}. The Jiepai Detachment acted as the
main discontinuity separating the extensional basin and the Baishifeng
pluton (Figure~\ref{fig5}b). Geological and geophysical evidence on
undeformed plutons points to a two-stage granite emplacement
supplied by several magma channels   \citep{Weietal2016}.

\begin{figure*}
{\vspace*{2pt}}
\includegraphics{fig05}
\caption{(a) Geological map, (b) map with published ages, and (c)
cross-section of the Hengshan dome   \citep[modified
from][]{Lietal2013,Weietal2016}.\label{fig5}\vspace*{5pt}}
\end{figure*}

The Jiepai detachment is ${\sim}$5--8~km wide, deforming the western part
of the Baishifeng pluton, as well as the western end of the Nanyue
pluton \citep{Zhang1994,Lietal2013}. Curving along the pluton, this ca
30\textdegree\ detachment developed a 2--4~km-thick fault zone by fluid
injection and foliated or mylonitized the granite and micaschist with
an average angle of  30\textdegree~\citep{Zhangetal2012}.
Well-preserved mineral and stretching lineation and quartz
microstructures indicate intermediate deformation temperature between
300--500~\textdegree C  \citep{Lietal2013,Weietal2016}. 

The hanging wall is mostly undeformed. The lower part of the Cretaceous
red bed continental deposits exposes poorly sorted conglomerates with
some pebbles broken by tension gashes  \citep{Weietal2016}. The major
component of pebbles in the conglomerate derived from deformed and
undeformed granite exposed by the detachment, suggesting a protracted
activity of the detachment and an early unroofing of the pluton
\citep{Lietal2016}. The overlying Early Cretaceous lacustrine basin
develops arrays of high-angle listric normal faults, suggesting
syn-extensional deposition \citep{Geetal1994}.

\subsubsection{Timing of deformation}\label{sec322}

Several thermochronology studies have been conducted in the Jiepai
detachment of the Hengshan dome
\citep{Lietal2013,Lietal2016,Wangetal2015}.  Age of the syn-deformation
granitic veins and magnetic fabrics of magmatic rocks show an early
stage of ductile shearing. Deformation in the shear zone occurred in
Early Cretaceous coeval with or shortly after the pluton emplacement 
\citep{Lietal2013,Weietal2016}. As a matter of fact, the biotite and
muscovite $^{40}$Ar--$^{39}$Ar ages from mylonitic rocks cluster in
100--90~Ma, except for two ages at 108~Ma (Supplementary Table~S1). 
These concentrated
cooling ages show a major fault movement period at early Late
Cretaceous. During this time, the fault slip rate reaches values as high as
2.4~mm/y if we use biotite $^{40}$Ar--$^{39}$Ar ages for calculation
(Figure~\ref{fig6}). Although the early fault activity has some
indirect evidence, it is still less robust because the late event has
strongly overprinted the early deformation fabrics and thus uplifted
and eroded those rocks bearing early information.

\begin{figure}
\includegraphics{fig06}
\caption{Sample ages plotted against fault-perpendicular distance from
the Jiepai Detachment. Age information and references are listed in
Supplementary Table S1.\label{fig6}}
{\vspace*{-2pt}}
\end{figure}

\subsection{Dayunshan}\label{sec33}

\subsubsection{Deformation pattern}\label{sec331}

The Dayushan (-Mufushan) dome is one of the largest Mesozoic plutons in
the north SCB (Figure~\ref{fig1}). Two phases of magmatic rocks form
this composite pluton (Figure~\ref{fig7}a,b), including a Late
Jurassic biotite granite of ${\sim}$150~Ma, and Early Cretaceous two-mica
granites of 131--127~Ma \citep{Wangetal2014,Jietal2017}. Host rocks of
these plutons are\unskip\break micaschist, phyllite and slate, derived from
Neoproterozoic to Early Paleozoic sandstone and mudstone protoliths
\citep{Shietal2013}. The contact metamorphism produced biotite,
muscovite, garnet, and andalusite. The Dayunshan detachment is
restricted to the NW border, bounding the Cretaceous to Paleogene basin
filled by red beds \citep{Jietal2018b}. This detachment can be
interpreted as the northeastern extension of the Ziyuan Detachment of the
Yuechengling dome (Figure~\ref{fig1}). At the southeast margin, a
brittle normal fault strikes parallel to the Dayunshan detachment and
probably develops in the similar tectonic setting \citep{Wangetal2014}.

\begin{figure*}
{\vspace*{4pt}}
\includegraphics{fig07}
{\vspace*{6pt}}
\caption{Geological map (a), map with published ages (b), and
cross-section (c) of the Dayunshan dome  
\citep[modified from][]{Jietal2018a,Jietal2018b}. \label{fig7}}
{\vspace*{4pt}}
\end{figure*}

The narrow ductile shear zone varies from 100 to 2000~m in the
Dayunshan dome (Figure~\ref{fig7}c). Within the detachment and
footwall, deformation increases from protomylonitic to mylonitic
granite. Cataclastic and brecciated mylonite argues for a brittle
overprint on the detachment. Consistent NW--SE trending lineation is
common on foliation parallel to the tongue-shaped pluton margin and
kinematic indicators show top-to-the NW shearing \citep{Jietal2018b}.
Mineral microstructures imply a deformation temperature at
400--500~{\textdegree}C~\citep{Jietal2018b}.  This structural observation
also concurs with rock magnetic fabrics on post- and sub-solidus
deformation in granites of the west, suggesting a syn-tectonic
\unskip\break
emplacement of the Early Cretaceous pluton
\citep{Jietal2018a,Jietal2018b}. In the hanging wall, conglomerate with
granite pebbles lays on top of the fault plane, as a direct indicator
of tectonic unroofing and erosion of the pluton. 

A Late Jurassic compression occurred during the Late Jurassic granite
emplacement. This compressional deformation foliated the margin of
biotite granite and folded and sheared the host rocks by top-to-the SSW
kinematics at ${\sim}$150~Ma \citep{Jietal2018b}. Intracontinental
compression can explain the tectonic impact here and in the adjacent
Jiuling belt as well  \citep{Chenetal2014,Lietal2016}. 

\subsubsection{Timing of deformation}\label{sec332}

The deformation stages correlate with the granite emplacement, which
are precisely constrained by zircon U--Pb ages of ${\sim}$150~Ma and
${\sim}$130~Ma, respectively (Figure~\ref{fig7}b). Compression appeared at
${\sim}$150~Ma, and the detachment only preserved one stage of
extensional deformation between 135~Ma and 120~Ma \citep{Jietal2018b}.
In contrast, the thermochronology data reveal a two-staged cooling
pattern, one fast cooling at ${\sim}$120~Ma, and one slower cooling at
${\sim}$95~Ma. During the Early Cretaceous, the detachment was active at
a high rate of ${\sim}$1.5~mm/y (Figure~\ref{fig8}). From 120~Ma to 95~Ma,
the detachment slowly slipped at a very low rate, or possibly became
inactive. During the Late Cretaceous, the existed detachment resumed
its normal faulting activity and exhumed the previously mylonitized rocks
\citep{Jietal2018b}. 

\begin{figure}
{\vspace*{4pt}}
\includegraphics{fig08}
{\vspace*{4pt}}
\caption{Sample ages plotted against fault-perpendicular distance from
the Dayunshan Detachment. Age information and references are provided
in Supplementary  Table S1.\label{fig8}}
\end{figure}

\subsection{Lushan}\label{sec34}

\subsubsection{Deformation pattern}\label{sec341}

The Lushan dome almost reaches the north margin of the Yangtze Craton
(Figure~\ref{fig1}). This dome has been considered as an extensional
structure since the 1990s  \citep{Xiangetal1993}. Then
\cite{Linetal2000} carried out a careful structural investigation to
establish multi-phased deformation and tectonic architecture of this
area. This dome has a NW--SE trending elliptical shape cored by Mesozoic
metamorphic rocks with Neoproterozoic protolith ages 
\citep{Linetal2000,Wangetal2013a,Yangetal2015,Yangetal2017}. A complex deformation
history that includes at least four phases since the Phanerozoic has
been recorded due to the influence from the Dabie orogenic belt and
Triassic orogenic belt of the SCC
\citep{Faureetal1998,Faureetal2016,Chuetal2012}.  The first two
pre-Cretaceous events are related to the Late Paleozoic to Triassic
collision between the SCB and NCC, causing an amphibolite-facies
metamorphism in the Neoproterozoic--Paleozoic series
\citep{BGMRJX1984,Linetal2000}. The latter two played a key role in the
formation of the Lushan dome during Cretaceous and the prevailing
NE--SW-striking structures with NW--SE kinematics. 

The phase of deformation of the detachment is still debated because of
multiphase tectonic overprinting. The core of the Lushan dome is
Cretaceous granites and metamorphic rocks. A NW-dipping main
detachment, the Wenquan Fault, controlled the deformation and
exhumation in the Cretaceous  \citep{Zhuetal2010a,Zhuetal2010b,Yangetal2015}, while
the Wuli Fault acted as a brittle--ductile boundary normal fault
accompanied with brittle faulted rocks (Figure~\ref{fig9}c). The
detachment consists of secondary shear zones and normal faults at the
west flank, separating the metamorphic rocks in the center, the
Neoproterozoic sedimentary-volcanic unit, and the Late Neoproterozoic
(Sinian) sedimentary rocks (Figure~\ref{fig9}a,c). The low-grade
metamorphic units above the gneissic core are characterized by dip-slip
ductile deformation towards the NW, and quartz fabrics from metamorphic
rocks determine the deformation temperature at 300--400~\textdegree C 
\citep{Linetal2000,Yangetal2015}. The Wuli fault cutting this dome at
the east flank, and later, brittle, top-to-the SE normal faulting
crosscut early extensional structures \citep{Linetal2000}. Hence, the
Lushan dome is an atypical extensional dome with bivergent but
diachronous slip sense at its two flanks. The detachment system of the
west and its related ductile deformation controlled the doming process,
while brittle normal faulting finally established the current geometry.

\begin{figure*}
\includegraphics{fig09}
\caption{Geological map (a), map with published ages (b), and
cross-section (c) of the Lushan dome 
\citep[modified from][]{Linetal2000}.\label{fig9}\vspace*{-5pt}}
\end{figure*}

\subsubsection{Timing of deformation}\label{sec342}

Previous studies on U--Pb dating clearly revealed an Early
Cretaceous metamorphic core of the Lushan dome (Figure~\ref{fig9}a,b).
Except analysis in Sinian rocks, zircon and titanite U--Pb ages of
the metamorphic core range from 127~Ma to 180~Ma, peaking at
${\sim}$135--140~Ma  \citep{Linetal2000,Yangetal2015}. The
$^{40}$Ar--$^{39}$Ar cooling ages are younger with one major group from
105 to 95~Ma and another group around 125~Ma 
\citep{Linetal2000,Zhuetal2010a,Zhuetal2010b,Yangetal2017}. Relating this age
difference between U--Pb and $^{40}$Ar--$^{39}$Ar methods to the
temperature difference between intermediate-temperature ductile
deformation and amphibolite-facies metamorphism, we find that NW--SE
extension may postdate the metamorphism in the core, and can be
identified with a low-temperature ductile phase in Early Cretaceous and
a lower temperature brittle phase in Late Cretaceous. The early phase
has a slow cooling because of a low slip rate of the detachment, while
the late brittle normal faulting leads to a relatively fast cooling
with a higher fault slip rate (Figure~\ref{fig10}). 

\begin{figure}
\vspace*{6pt}
\includegraphics{fig10}
\vspace*{8pt}
\caption{Sample ages plotted against fault-perpendicular distance from
the Lushan Detachment. Age information and references are listed in
Supplementary Table S1.\label{fig10}}
\end{figure}

\vspace*{2pt}
\subsection{Lianhuashan}\label{sec35}
\vspace*{2pt}
\subsubsection{Deformation pattern}\label{sec351}

The Lianhuashan dome is a newly discovered extensional dome. It
situates in the south of the SCB, far from the rest of extensional
domes located in the central or northern SCB (Figure~\ref{fig1}). This
structure has the same NE--SW long-axis as other domes but mainly
consists of Mesozoic rock assemblages, including Jurassic to Cretaceous
batholith, Early to Middle Jurassic sedimentary rocks, Jurassic to
Cretaceous volcanic rocks and Late Cretaceous sediments
\citep{BGMRGD1988}. The Wuhua Fault represents the boundary detachment
and juxtaposes the Cretaceous basin with the Lianhuashan batholith
\mbox{(Figure~\ref{fig11}).} Southwards, this fault connects the Danshui Fault
and constitutes a 200~km-long ductile normal fault system. 

\begin{figure*}
{\vspace*{-3pt}}
\includegraphics{fig11}
{\vspace*{-3pt}}
\caption{Geological map (a), map with published ages (b), and
cross-section (c) of the Lianhuashan dome 
\citep[modified from][]{Lietal2020}.\label{fig11}}
{\vspace*{-3pt}}
\end{figure*}


In the north, the detachment bounded and deformed the Lianhuashan
pluton with a 1--2~km thick ductile shear zone. NW-dipping
(${<}$30\textdegree) mylonitic foliation, NW-trending lineation
and shear indicators demonstrate a top-to-the NW shear sense. Both
quartz fabrics and $c$-axis orientation patterns imply an intermediate
deformation temperature at 350--500~\textdegree C \citep{Lietal2020}.
The footwall includes Jurassic to Cretaceous volcanic rocks, Late
Jurassic plutons, and Early Cretaceous sedimentary rocks
\citep{BGMRGD1988,Zhuoetal2011}. Two phases of shortening are
reported in this unit under intermittent NW--SE compression. The early
one forms 400--500~\textdegree C ductile shearing with 
top-to-the-W \unskip\break
kinematics, and the late one only develops brittle
strike-slip faults \citep{Lietal2020}.

In the hanging wall, Late Cretaceous conglomerate and sandstone are
directly deposited on the detachment. Most of the pebbles are
metasandstone, volcanic rocks, and granite from the footwall. These
syn-tectonic deposits are also truncated by NE--SW striking brittle
normal faults. The detachment activity can be divided into two
stages, an early stage of ductile deformation and a late stage of
brittle deformation \citep{Lietal2020}, but they may belong to the same
stage developed in different structural levels. 

The Lianhuashan dome witnesses the whole compression--extension cycles
of the SCB in the Mesozoic \citep{Lietal2020}. Its final geometry was
controlled by its boundary detachment fault, the Wuhua Fault. This
asymmetrical dome-detachment model resembles the other extensional
domes, which all have a sole detachment at one side to form the
half-dome geometry.

\subsubsection{Timing of deformation}\label{sec352}

The Lianhuashan dome's granitic core was crystallized from 164~Ma to
153~Ma; then the overlying Jurassic-Cretaceous volcanic rocks covered
this pluton between 155~Ma and 133~Ma (Figure~\ref{fig11}b).
Disregarding the compression, all cooling ages suggest that the
extensional deformation accommodated by the Wuhua Fault was exclusively
active in Late Cretaceous, leading to the rapid exhumation of the
sheared rocks at 100--96~Ma \citep{Lietal2020}. All the cooling ages are
very concentrated, which also underpins a stronger Late Cretaceous
extension during the episodic extension of the SCB. 
\vspace*{-8pt}

\section{Domes without detachment}\label{sec4}
Three other extensional structures without detachment faults formed
during the two extensional phases. Some of them have early ductile
shear zones with perpendicular kinematics to the regional NW--SE
extension direction, and late NW--SE brittle--ductile extension. Because
of a possible compressional origin, we do not ascribe these ductile
shear zones to dome-forming structures. Below, we briefly introduce
their structural and geochronological\unskip\break features that also suggest a
widespread Cretaceous extension in the SCB.

\subsection{Wugongshan}\label{sec41}

The Wugongshan dome is one of the first well-investigated extensional
domes in the SCB. It was initially interpreted as a Triassic dome
induced by the intracontinental deformation of the Dabie orogen
\citep{Faureetal1996}. Although this dome was once interpreted as a
metamorphic core complex, the symmetrical normal sense ductile shearing
at the northern and southern flanks refutes a Cordillera-type
metamorphic core complex model which show consistent kinematics 
\citep{Wernicke1981,ListerDavis1989}. The Neoproterozoic to Paleozoic
magmatic-metamorphic complex is separated from unmetamorphosed rocks by
the Triassic ductile shear zones \citep{Faureetal1996}. In the south,
conglomerates are highly stretched in the Triassic sedimentary cover
(Figure~\ref{fig12}a).
%Two ductile shear zones bounding the dome and their dip-slip activity in established this extensional structure,
Two boundary ductile shear zones and their dip-slip activity formed this extensional structure,
i.e.
top-to-the N and top-to-the S shearing at the north and south margins,
respectively (Figure~\ref{fig12}c). The cooling ages of biotite and
muscovite from mylonite clustered at 260--220~Ma suggest that the dominant
deformation occurred in Permian-Triassic times.

\begin{figure*}
\vspace*{-2pt}
\includegraphics{fig12}
\vspace*{-2pt}
\caption{Geological map (a), map with published ages (b), and
cross-section (c) of the Wugongshan dome 
\citep[modified from][]{Faureetal1996,Wangetal2014}. SX-JS-PX:
Shaoxing-Jiangshan-Pingxiang.\label{fig12}}
\vspace*{-3pt}
\end{figure*}

Cretaceous extension across the SCB reactivated the dome and led to
further uplifting and exhumation
\citep{Tangetal1991,Faureetal1996,Shuetal1998,Louetal2002}. Ductile
deformation with top-to-the S shear sense in the Cretaceous pluton and
Early Cretaceous $^{40}$Ar--$^{39}$Ar ages (${\sim}$130~Ma) \mbox{reveal} a
later event reactivating the boundary ductile faults. The related
structures and their kinematic evolution to understand the Cretaceous
doming process of Wugongshan, however, need more structural observation
and thermochronology work to verify \mbox{(Figure~\ref{fig12}b)}. 

\subsection{Hongzhen}\label{sec42}

This dome preserves contrasting kinematics in the deep crustal units
and the brittlely deformed hanging wall, reflecting a decoupled
deformation pattern in this dome  \citep{Zhuetal2010a}. 
From east to
west, the Hongzhen dome consists of undeformed Hongzhen granite, highly
sheared Dongling metamorphic complex, Paleozoic strata, and Cretaceous
half-graben basin (Figure~\ref{fig13}) 
\citep{Zhouetal1988,Zhuetal2010a}. Within the lower crustal unit, the
Dongling complex displays a high-grade amphibolite-facies metamorphism,
and extensive ductile shearing with a top-to-the SW sense. This stage
is interpreted as an early shearing initiated at Late Jurassic to Early
Cretaceous. Following this event is a second stage of NW--SE \mbox{extension}
at ${\sim}$128--120~Ma accompanied with the emplacement of the Hongzhen
granite. NE--SW-striking brittle--ductile normal faults modified or cut
the early structures in metamorphic rocks and the Paleozoic sedimentary
cover  \citep{Zhuetal2007,Zhuetal2010a,Zhuetal2010b,Liuetal2016}, and
established the final asymmetrical geometry with a low-angle boundary
in the west and a high-angle boundary in the east. Hence, this dome
presents an early NE--SW deformation perpendicular to the late
extension but is comparable with similar deformation recorded in Lushan
and Dayunshan. Subsequently, the regional stress field changed to
NW--SE extension and reshaped and exhumed the metamorphic core by
NW-directed brittle--ductile shear zones.

\begin{figure*}
\vspace*{3pt}
\includegraphics{fig13}
\vspace*{2pt}
\caption{Geological map (a) and cross-section (b) of the Hongzhen
dome \citep[modified from][]{Zhuetal2010a,Zhuetal2010b}.
\label{fig13}}
\vspace*{2pt}
\end{figure*}

\subsection{Huangling}\label{sec43}

The Huangling anticline is a weakly deformed extensional dome without
any tectonic discontinuities \mbox{between} the metamorphic basement and
sedimentary cover (Figure~\ref{fig14}). It has the oldest rocks of South
China, the Kongling group of ${\sim}$3.3--3.2~Ga, of the SCB 
\citep{Qiuetal2000,Zhangetal2006a,Zhangetal2006b,Gaoetal2011}. The
Huangling granitoids of ${\sim}$820~Ma intruded into the Archean to
Paleoproterozoic basement rocks. On the both sides of the
magmatic-metamorphic rocks, the sedimentary sequence is composed of
Late Neoproterozoic to Jurassic rocks formations unconformably covering
the basement rocks. This dome lacks a basal detachment. Cretaceous
doming and uplifting exhumed the Huangling anticline, forming
multi-horizon dip-slip in rheologically weak sedimentary layers and
high-angle normal faults that controlled the Cretaceous red bed
deposition of the eastern and western basins \citep{Jietal2014}.
Sheared pebbles in pelitic matrix are good indicators to show a
bivergent sense of extension, i.e., top-to-the W at its western margin,
and top-to-the E at the eastern margin. The extension timing varies in
\mbox{different} models, but structural and thermal modeling both reveal a
long extensional process lasting from 160~Ma to 110~Ma
\citep{Huetal2006,Shenetal2012,Jietal2014}.

\begin{figure*}
\vspace*{-2pt}
\includegraphics{fig14}
\vspace*{-4pt}
\caption{Geological map (A) and cross-section (B) of the Huangling dome
\citep[modified from][]{Jietal2014}. Ar--Ar ages are not shown because
they are all Precambrian and not related to Cretaceous doming.\label{fig14}}
\vspace*{-2pt}
\end{figure*}

\section{Discussion}\label{sec5}

\subsection{Features of the two-stage extension}\label{sec51}

Compilation of structural and geochronology data of the extensional
domes in the SCB allows us to illustrate features of the extensional
domes and thus establish the Cretaceous two-stage extension 
(Figures~\ref{fig16}
and~\ref{fig17}). Although the central part of all the domes is occupied by
plutons of variable crystallization ages, they were formed in
temporally and spatially heterogeneous continental extension of the
SCB. Firstly, their geometry varied when the crust of the SCB was
stretched in the Cretaceous. There are three types of domes, (1) domes
exhumed by a single detachment, (2) domes exhumed by a detachment with
a high-angle normal fault, and (3) domes exhumed by buoyant doming
without a detachment. Among the SCB domes, four of them that belong to
type 1: Yuechengling, Hengshan, Lianhuashan, and Dayunshan
(Figure~\ref{fig15}a), while two domes, Lushan and Hongzhen, are type 2
domes showing quasi-symmetrical extension. The two types both have a
shallow-dipping detachment at the western margin of the domes. They
also develop northwest/west-dipping foliation and top-to-the NW/W shear
sense. Ductile deformation formed in the similar thermal condition, at
middle to high greenschist facies around 300--500~\textdegree C. In
contrast to type 1, the type 2 domes developed high angle faults at the
eastern sides (Figure~\ref{fig15}b). These later faults cut the early,
low angle foliation, facilitated the exhumation of the core pluton and
metamorphic rocks, and finalized the shape of the domes. Type 3 domes
(Figure~\ref{fig15}c) including Wugongshan and Huangling show Cretaceous
cooling and the corresponding deformation is mostly brittle faulting and
layer-slip that accommodate the extension. This type of doming processes
results in buoyancy-dominated exhumation that exposed the mid-crustal
rocks and the overlying\unskip\break sedimentary cover, and forms several normal
faults to accommodate crustal extension instead of a sharp
discontinuity/detachment.

\begin{figure*}
\includegraphics{fig15}
\caption{Geometry of the three types of domes. (a) Dome with one
dominant detachment. (b) Dome with one detachment and one high angle
fault both controlling the extensional process. (c) Dome formed by
buoyant doming process without detachment. Note that there may be
several slip layers within the sedimentary cover of the central
granite.\label{fig15}}
\end{figure*}

\begin{figure*}
\includegraphics{fig16}
\caption{Age summary of all extensional domes with detachments reviewed
in the text. Data are compiled in the 
Supplementary Table S1 of the appendix data.
Different dating methods are indicated with colors.\label{fig16}}
\end{figure*}

\begin{figure*}
\includegraphics{fig17}
\caption{Tectonic models showing how cyclical reworking thinned the
lithosphere of the SCB 
\citep[modified after][]{Chuetal2019,Chuetal2020}.\label{fig17}}
\end{figure*}

Secondly, inconsistent timing of doming coincided with the varied dome
structures, {showing} single or two-staged extension. Among them,
Yuechengling, Lushan, Dayunshan, Lianhuashan, Hengshan, and Huangling
are those which carry two-stage structural information, while Hongzhen
and Wugongshan only preserve one stage of extension during the Early
Cretaceous (Figure~\ref{fig16}). The Early Cretaceous extension abounds
in the eastern half of the SCB and is thermochronologically imprinted
in every extensional dome, whereas the Late Cretaceous extension seems
more localized and intense. Estimation of detachment activities shows
that those domes that have experienced two-staged stretching display a
faster detachment slip rate in Late \mbox{Cretaceous} than that of Early
Cretaceous (Figures~\ref{fig4},~\ref{fig8}
and~\ref{fig10}). Structural evidence from the Yuechengling dome
explicitly displays two extensional phases in the Tianhu Fault and
Ziyuan Detachment \citep{Chuetal2019,Fengetal2022b}. The
first stage developed limited extension and exhumation, while the
second stage has greater extension and deformation in this dome. The
evidence supports a weaker extension during the early extension, and a
faster and stronger extension in the later extension. 

The two stages of extension characterize the Cretaceous
tectonic evolution of the SCB by  heterogenous deformation
in the extensional domes. The higher rates of detachment
(Figures~\ref{fig4},~\ref{fig6},~\ref{fig8} and~\ref{fig10}) and
crustal stretching of the Late Cretaceous extension also reflect a
significant change of thermal state and structure of the South China
lithosphere.


\subsection{Implications to lithosphere 
\mbox{thinning}/de{\hbreak}struction of South
China}\label{sec52}

Since the identification of the MCC in the Western North America,
continental extension has become an important continental
tectonics revolutionizing our understanding of continental deformation
\citep{DavisConey1979,Wernicke1981}. The East Asia continent at the
western Pacific margin is an important example of back-arc continental
extension \citep{Zhouetal2006,Lietal2014,Chuetal2019}. As the
southern component, the SCB underwent significant tectonic reworking in
this period, which consists of distinctive compression--extension
intervals. This cyclical intracontinental compression and extension
imposed by the subduction dynamics modified the lithosphere of the SCB
and can be defined as another archetype of lithosphere thinning or
destruction. Synthesis of the extensional domes reveals a stronger and
faster deformation stage in the Late Cretaceous. In contrast, a major
magmatic flare-up occurred in the Early Cretaceous, while in the Late
Cretaceous flare-up produced less plutons and scarce volcanic
formations (Figure~\ref{fig2}b,c). The two stages of
extension and related volcanism spatially overlap in a
${\sim}$1000~km wide region of the central and eastern SCB. Their varied
deformation patterns and settings may reflect thermal, compositional,
and structural change of the lithosphere state between the two periods.
\looseness=-1

The Yangtze Block preserves a cratonic core in the Sichuan Basin whose
lithosphere exceeds 150--180~km thick, while the rest of the block has a
thinned lithosphere of ${\sim}$100~km thick 
\citep{Zhangetal2018,Dengetal2021}. The sparse distribution of Archean
to Paleoproterozoic rock assemblages likely denotes an originally
larger cratonic lithosphere beneath the Yangtze Craton 
\citep{ZhangZheng2013,Tianetal2022}. Similar to the well-studied North
China Craton destruction 
\citep{Zhuetal2012,Zhuetal2021,Wuetal2019,LinWei2020}, the Yangtze
Craton also underwent extensive thinning of its lithosphere compensated
by the Cretaceous crustal extension. During the Early Cretaceous
extension, extensional domes popped up along a weak zone of the SCB,
the Neoproterozoic suture zone of the JSF and CLF or the Triassic
Xuefengshan--Jiuling Belt (Figure~\ref{fig1}). Along this zone,
detachments localize the deformation and stretch the crust under mid
to high temperature (400--500~\textdegree C). Away from the weak zone,
coeval deformation was either absent (Lianhuashan), or localized at
high-angle brittle--ductile (${\sim}$300~\textdegree C) normal faults
(Yuechengling). Less deformed zones to the east and west of this N--S
line of dome indicate a rigid, cool, and less modified lithosphere
resistant to deformation. In the Late Cretaceous, extension propagated
westerly and easterly and triggered mid to high-temperature
(400--500~\textdegree C) ductile deformation in the neighboring
regions, including Yuechengling and Lianhuashan domes. As exemplified
in Yuechengling, the Late Cretaceous ductile shearing has a higher
temperature and extension amount that the Early Cretaceous
\citep{Fengetal2022b}. 
It thus suggests a warmed, thinned and easily
deformed lithosphere of Late Cretaceous, and a cool and thick
lithosphere in Early Cretaceous. This lithosphere thinning or
destruction beneath Yuechengling or the adjacent regions along-strike
occurred in the Late Cretaceous. Thus, the Early Cretaceous extension
manifests a deep lithosphere removal along the JSF and CLF, and the
Late Cretaceous extension enlarged this removal as attested by
detachment in the further west regions.

Finally, we propose a progressively lithospheric thinning model to
explain the process that destructed or dismembered the lithosphere of
the Yangtze Craton. The SCB experienced a unique, cyclical
compression--extension tectonic reworking in which both compression and
extension facilitate the \mbox{propagated} lithospheric thinning. The first
compression occurred in Late Jurassic-Earliest Cretaceous in response
to the shallow subduction of the Paleo-Pacific slab
\citep{Chuetal2019,Lietal2020}. It shortened the crust of the interior
SCB, and more importantly, it deformed the crust and the subcontinental
lithosphere by creating thrust fault systems rooted in the JSF-CLF, a
weak zone within the SCB (Figure~\ref{fig17}a). These faults modified
the lithosphere and generated weak zones within the lithosphere. The
first extension and magmatism resulted from the Paleo-Pacific slab
roll-back in the Early Cretaceous and caused the eastern edge of the
thick lithosphere of the Yangtze Craton to dismember and collapse. This
is the first stage of \unskip\break destruction that breached ${\sim}$200~km wide of
lithosphere (Figure~\ref{fig17}b). Subsequently, the second phase of
compression resulted from the shallowing of the subducted Paleo-Pacific slab
and shut the regional magmatism in the SCB \citep{Chuetal2019}. Within
the SCB, the deformed zone migrated towards the Sichuan Basin and
ruptured the crust and lithospheric mantle beneath Xuefengshan, where
the lithosphere was intact or less destructed during the first stage of
extension (Figure~\ref{fig17}c). During the second stage of extension
when the Paleo-Pacific slab rolled back again in Late Cretaceous, the
lithosphere repeated the destruction process (Figure~\ref{fig17}d).
Extension was accommodated in detachments and normal faults that
inversed the previous thrust faults. This extension detached the
lithosphere of the Xuefengshan Belt, and therefore enlarged the
lithosphere damage toward the west by another ${\sim}$200~km. The rapid
change of regional stress provoked switch between compression and
extension, which resulted in a gradually destructed cratonic
lithosphere, where lithosphere thickness varies significantly beneath
the Xuefengshan Belt and eastern end of the East-Sichuan Thrust Belt
\citep{Dengetal2021}. In the second stage, our work suggests a more
intense extension, but the magmatic response is weaker than the Early
Cretaceous extension. One possibility is that the subduction zone
dynamics is different between the two extensional stages. A less input
of fluid-rich sediments or steep subduction after roll-back commonly
cause less magmatism or restricted magma at the very east margin of
South China. Another possibility is that the underlying lithosphere had
already been extracted in the Early Cretaceous, thus became more
refractory during the second extensional stage, so that the magma was less
abundant in the later but stronger extension stage.\looseness=-1

By compiling the existing data of extensional domes of the SCB, we
propose a new model of multistage lithospheric destruction for the SCB
(Figure~\ref{fig17}), that is different from the fierce delamination of the North
China Craton. This inconsistency between cyclical magmatism and
deformation contrasts with the North China Craton where magma
production is proportional to lithospheric extension, which culminated
at ${\sim}$130~Ma  \citep{Wuetal2008,LinWei2020,Liuetal2021}.
A long-lasting slab roll-back and continuous fluid injection promoted a
rapid and extensive lithosphere delamination  
\citep{Chenetal2008,Chenetal2014,Zhuetal2012,Wuetal2019}. 
Another\unskip\break endmember of mechanic
lithospheric destruction operated in Mesozoic South China. Fast change
of compression and extension prevented large-scale delamination but
gradually and progressively impaired the thick cratonic lithosphere.
This model concurs with recent geophysical observations in which
several SE-dipping structures have been identified in the lithosphere
of the Yangtze Craton. Their parallel distribution and NE--SW striking
may preserve the tectonic advancing of cyclical intracontinental belts
from SE to NW resulted from Paleo-Pacific subduction dynamics
\citep{Lietal2022,Lietal2023}.

\section{Conclusion and perspectives}\label{sec6}
The Mesozoic Paleo-Pacific subduction systems at the East Asian
continental margin produced a peculiar compression--extension cycle that
greatly impacted the intracontinental tectonics of the South China
Block. We synthesize the structural pattern and timing of the
extensional domes in this highly reworked continental block and propose
a new mode of lithospheric destruction. In contrast to the swift,
one-cycle lithosphere delamination of the North China Craton, the
destruction process operates in a cyclical, progressive manner in which
compression destabilized the edge of the cratonic lithosphere and the
following extension destructs the unstable part to thin the
lithosphere. This process, as an endmember of lithospheric destruction
mechanisms, requires cyclical tectonics of the subduction zone and the
overriding plate, which has been widely {reported} in the Cordilleras of
the eastern \mbox{Pacific} \mbox{margin}
\citep{DeCellesetal2009,DeCellesetal2015},
and East Asia of the western Pacific margin
\citep{Chuetal2019,MengLin2021}. The progressive lithosphere
destruction model may also explain how ancient cratons shrink by
subduction-related tectonics.

This working model still need further geological and geophysical
investigation to verify the detailed process. Most extensional domes
situate at the both sides of the Jiangshan-Shaoxing and Chenzhou-Linwu
faults (Figure~\ref{fig1}). Recent work exposes some new extensional
domes and detachments \citep{Chuetal2019,Lietal2020}, but it remains
poorly understood whether unidentified domes are developed in the
exterior of this region. Precise reconstruction of the two extensional
stages also requires the stretching amount and rate of all detachments,
as well as cross-continent evaluation on thermal status of lithosphere.
This work intends to attract more attention to the SCB which carries so
much and so distinct information for continental reworking, with a
craving for a complete view on the lithosphere destruction and new
light to continent formation-reworking-destruction processes.

\section*{Declaration of interests}
The authors do not work for, advise, own shares in, or receive funds
from any organization that could benefit from this article, and have
declared no affiliations other than their research organizations.
                                                                 
\section*{Acknowledgements}
We thank two anonymous reviewers for their insightful comments and
suggestions. We appreciate the insightful discussion with Dr. Fuyuan Wu
and Dr. Ling Chen. This work also benefited from the discussions in
Coffice 442 in IGGCAS. All data in this study are provided in the
appendix files.

\CDRGrant[NSFC]{41872208}
\CDRGrant[NSFC]{91855212}
\CDRGrant[YIPA]{2019065}

\back{}

\section*{Supplementary data}
Supporting information for this article is available on the journal's
website under \printDOI\ or from the author. 

\CDRsupplementaryTwotypes{supplementary-material}{\cdrattach{Table-S1.xlsx}}

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