TY - JOUR
T1 - Lower Cretaceous Xigaze ophiolites formed in the Gangdese forearc
T2 - Evidence from paleomagnetism, sediment provenance, and stratigraphy
AU - Huang, Wentao
AU - van Hinsbergen, Douwe J.J.
AU - Maffione, Marco
AU - Orme, Devon A.
AU - Dupont-Nivet, Guillaume
AU - Guilmette, Carl
AU - Ding, Lin
AU - Guo, Zhaojie
AU - Kapp, Paul
N1 - Funding Information:
This work was funded by the U.S. NSF Continental Dynamics grant EAR-1008527 ‘The Suturing Process: Insight from the India–Asia collision zone’, the Netherlands Organisation for Scientific Research ( NWO ) with VIDI grants to G.D.-N. and D.J.J.v.H., the European Research Council (ERC) Starting Grant number 306810 (SINK) to D.J.J.v.H., the Alexander von Humboldt Foundation grant to G.D.-N., and the Cai Yuanpei program of the French Ministry of Foreign Affairs and Ministry of Higher Education and Research , and the Ministry of Education of the People's Republic of China . We thank Pierrick Roperch for lab assistance, Xiao Wang and Shun Li for field assistance. We are grateful to Xiumian Hu, an anonymous reviewer, and the Editor An Yin for their constructive comments and suggestions.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - The India-Asia suture zone of southern Tibet exposes Lower Cretaceous Xigaze ophiolites and radiolarian cherts, and time-equivalent Asian-derived clastic forearc sedimentary rocks (Xigaze Group). These ophiolites have been interpreted to have formed in the forearc of the north-dipping subduction zone below Tibet that produced the Gangdese magmatic arc around 15-20°N, or in the forearc of a sub-equatorial intra-oceanic subduction zone. To better constrain the latitude of the ophiolites, we carried out an integrated paleomagnetic, geochronologic and stratigraphical study on epi-ophiolitic radiolarites (Chongdui and Bainang sections), and Xigaze Group turbiditic sandstones unconformably overlying the ophiolite's mantle units (Sangsang section). Detrital zircon U-Pb geochronology of tuffaceous layers from the Chongdui section and sandstones of the Xigaze Group at the Sangsang section provides maximum depositional ages of 116.5. ±. 3.1 Ma and 128.8. ±. 3.4 Ma, respectively, for the Chongdui section and an Asian provenance signature for the Xigaze Group. Paleomagnetic analyses, integrated with rock magnetic experiments, indicate significant compaction-related inclination 'shallowing' of the remanence within the studied rocks. Two independent methods are applied for the inclination shallowing correction of the paleomagnetic directions from the Sangsang section, yielding consistent mean paleolatitudes of 16.2°N [13°N, 20.9°N] and 16.8°N [11.1°N, 23.3°N], respectively. These results are indistinguishable from recent paleolatitude estimates for the Gangdese arc in southern Tibet. Radiolarites from the Chongdui and Bainang sections yield low paleomagnetic inclinations that would suggest a sub-equatorial paleolatitude, but the distribution of the paleomagnetic directions in these rocks strongly suggests a low inclination bias by compaction. Our data indicate that spreading of the Xigaze ophiolite occurred in the Gangdese forearc, and formed the basement of the forearc strata.
AB - The India-Asia suture zone of southern Tibet exposes Lower Cretaceous Xigaze ophiolites and radiolarian cherts, and time-equivalent Asian-derived clastic forearc sedimentary rocks (Xigaze Group). These ophiolites have been interpreted to have formed in the forearc of the north-dipping subduction zone below Tibet that produced the Gangdese magmatic arc around 15-20°N, or in the forearc of a sub-equatorial intra-oceanic subduction zone. To better constrain the latitude of the ophiolites, we carried out an integrated paleomagnetic, geochronologic and stratigraphical study on epi-ophiolitic radiolarites (Chongdui and Bainang sections), and Xigaze Group turbiditic sandstones unconformably overlying the ophiolite's mantle units (Sangsang section). Detrital zircon U-Pb geochronology of tuffaceous layers from the Chongdui section and sandstones of the Xigaze Group at the Sangsang section provides maximum depositional ages of 116.5. ±. 3.1 Ma and 128.8. ±. 3.4 Ma, respectively, for the Chongdui section and an Asian provenance signature for the Xigaze Group. Paleomagnetic analyses, integrated with rock magnetic experiments, indicate significant compaction-related inclination 'shallowing' of the remanence within the studied rocks. Two independent methods are applied for the inclination shallowing correction of the paleomagnetic directions from the Sangsang section, yielding consistent mean paleolatitudes of 16.2°N [13°N, 20.9°N] and 16.8°N [11.1°N, 23.3°N], respectively. These results are indistinguishable from recent paleolatitude estimates for the Gangdese arc in southern Tibet. Radiolarites from the Chongdui and Bainang sections yield low paleomagnetic inclinations that would suggest a sub-equatorial paleolatitude, but the distribution of the paleomagnetic directions in these rocks strongly suggests a low inclination bias by compaction. Our data indicate that spreading of the Xigaze ophiolite occurred in the Gangdese forearc, and formed the basement of the forearc strata.
KW - Inclination shallowing
KW - Paleomagnetism and rock magnetism
KW - Sedimentary contact
KW - Xigaze ophiolite
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U2 - 10.1016/j.epsl.2015.01.032
DO - 10.1016/j.epsl.2015.01.032
M3 - Article
AN - SCOPUS:84922699528
VL - 415
SP - 142
EP - 153
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
ER -