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Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya.

ABSTRACT: Exhumation of the southern Tibetan plateau margin reflects interplay between surface and lithospheric dynamics within the Himalaya-Tibet orogen. We report thermochronometric data from a 1.2-km elevation transect within granitoids of the eastern Lhasa terrane, southern Tibet, which indicate rapid exhumation exceeding 1 km/Ma from 17-16 to 12-11 Ma followed by very slow exhumation to the present. We hypothesize that these changes in exhumation occurred in response to changes in the loci and rate of rock uplift and the resulting southward shift of the main topographic and drainage divides from within the Lhasa terrane to their current positions within the Himalaya. At ∼17 Ma, steep erosive drainage networks would have flowed across the Himalaya and greater amounts of moisture would have advected into the Lhasa terrane to drive large-scale erosional exhumation. As convergence thickened and widened the Himalaya, the orographic barrier to precipitation in southern Tibet terrane would have strengthened. Previously documented midcrustal duplexing around 10 Ma generated a zone of high rock uplift within the Himalaya. We use numerical simulations as a conceptual tool to highlight how a zone of high rock uplift could have defeated transverse drainage networks, resulting in substantial drainage reorganization. When combined with a strengthening orographic barrier to precipitation, this drainage reorganization would have driven the sharp reduction in exhumation rate we observe in southern Tibet.

SUBMITTER: Tremblay MM

PROVIDER: S-EPMC4593086 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya.

Tremblay Marissa M MM Fox Matthew M Schmidt Jennifer L JL Tripathy-Lang Alka A Wielicki Matthew M MM Harrison T Mark TM Zeitler Peter K PK Shuster David L DL

Proceedings of the National Academy of Sciences of the United States of America 20150914 39

Exhumation of the southern Tibetan plateau margin reflects interplay between surface and lithospheric dynamics within the Himalaya-Tibet orogen. We report thermochronometric data from a 1.2-km elevation transect within granitoids of the eastern Lhasa terrane, southern Tibet, which indicate rapid exhumation exceeding 1 km/Ma from 17-16 to 12-11 Ma followed by very slow exhumation to the present. We hypothesize that these changes in exhumation occurred in response to changes in the loci and rate o ...[more]

PMID: 26371325

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Project description:The composition of many Chenopodiaceae genera in different parts of Himalaya and Tibet has been insufficiently known or contradictory. A revision of the family in Himalaya including Bhutan, Nepal, parts of India (Himachal Pradesh, Jammu and Kashmir, Sikkim and Uttarakhand) and Tibet (Xizang, China) is presented for the first time. Altogether, 57 species from 20 genera are reported, including three species new to science (Agriophyllumtibeticum, Salsolaaustrotibetica and Salsolahartmannii). Atriplexcentralasiatica, Corispermumdutreuilii and Salsolamonoptera are identified as new records for India and Chenopodiumpamiricum is recorded in China for the first time. Dysphaniaambrosioides and Sympegmaregelii are recorded for Xizang. The generic and species keys, species distributions (including maps) and taxonomic notes are provided. We indicate for the first time that the presence of short yellow hairs is the remarkable morphological characteristic of the genus Grubovia. Evident heterocarpy and heterospermy is found in Dysphania for the first time (Dysphaniatibetica). Agriophyllumpungens, Atriplexcrassifolia, Atriplexlaciniata, Atriplexsagittata, Axyrisamaranthoides, Axyrishybrida, Bassiaindica, Corispermumkorovinii, Dysphaniaschraderiana (=Chenopodiumfoetidum auct.), Halocharisviolacea and Suaedamicrosperma are excluded from the species list. Neobotrydiumcorniculatum is synonymised with Dysphaniakitiae, Neobotrydiumlongii with Dysphaniahimalaica and Neobotrydiumornithopodum seems to be conspecific with Dysphanianepalensis. Corispermumladakhianum is a new synonym of Corispermumtibeticum. Amaranthusdiandrus is added to the synonyms of Acroglochinpersicarioides, and Bassiafiedleri, previously considered as conspecific with Gruboviadasyphylla, is added to the synonymy of Bassiascoparia. Lectotypes of Anabasisglomerata (≡Halogetonglomeratus), Halogetontibeticus (=Halogetonglomeratus), Amaranthusdiandrus (=Acroglochinpersicarioides), Chenopodiumtibeticum (≡Dysphaniatibetica), Corispermumdutreuilii, Corispermumfalcatum, Corispermumlhasaense, Corispermumpamiricumvar.pilocarpum (=Corispermumgelidum, syn. nov.), Corispermumtibeticum, Kochiaindica(≡Bassiaindica), Kochiaodontoptera (≡Bassiaodontoptera) and Salsolamonoptera are selected. Out of 53 native elements, 42 are restricted in their distribution to Himalaya and Tibet at altitudes 2000-4500 m above sea level. The greatest taxonomic diversity of the Chenopodiaceae is represented in Jammu and Kashmir (India) and Xizang (China) with a continuous decrease in the number of species southwards.

Dataset Information

Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya.

Publications

Erosion in southern Tibet shut down at ∼10 Ma due to enhanced rock uplift within the Himalaya.

Similar Datasets

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